To access the additional media content available with this e-book via Thieme MedOne, please use the code and follow the instructions provided at the back of the e-book. Atlas of Anatomy Fourth Edition Edited by Anne M. Gilroy, MA Professor Emeritus Department of Radiology University of Massachusetts Medical School Worcester, Massachusetts Brian R. MacPherson, PhD Professor and Vice Chair Department of Neuroscience University of Kentucky College of Medicine Lexington, Kentucky Jamie C. Wikenheiser, PhD Associate Professor Department of Anatomy and Neurobiology UC Irvine School of Medicine Irvine, California Based on the work of Michael Schuenke, MD, PhD Institute of Anatomy Christian Albrechts University Kiel Kiel, Germany Erik Schulte, MD Department of Functional and Clinical Anatomy University Medicine Johannes Gutenberg University Mainz, Germany Udo Schumacher, MD, FRCPath, CBiol, FSB, DSc Institute of Anatomy and Experimental Morphology Center for Experimental Medicine University Cancer Center University Medical Center Hamburg-Eppendorf Hamburg, Germany Illustrations by Markus Voll Karl Wesker 2113 illustrations Thieme New York · Stuttgart · Delhi · Rio de Janeiro Illustrators: Markus Voll and Karl Wesker Development Editor: Judith Tomat Production Editor: Barbara Chernow Compositor: Carol Pierson, Chernow Editorial Services, Inc. Library of Congress Cataloging-in-Publication Data Names: Gilroy, Anne M., editor. | MacPherson, Brian R., editor. | Wikenheiser, Jamie C., editor. | Voll, Markus M., illustrator. | Wesker, Karl, illustrator. | Schünke, Michael. Thieme atlas of anatomy. Title: Atlas of anatomy / edited by Anne M. Gilroy, Brian R. MacPherson, Jamie C. Wikenheiser ; based on the work of Michael Schuenke, Erik Schulte, Udo Schumacher ; illustrations by Markus Voll, Karl Wesker. Other titles: Atlas of anatomy (Gilroy) Description: Fourth edition. | New York : Thieme, [2020] | Includes index. | Summary: “An updated atlas that provides a clear, accurate, and fully illustrated guide to human anatomy”— Provided by publisher. Identifiers: LCCN 2019058797 (print) | LCCN 2019058798 (ebook) | ISBN 9781684202034 (paperback) | ISBN 9781684202041 (ebook) Subjects: MESH: Anatomy | Atlas Classification: LCC QM25 (print) | LCC QM25 (ebook) | NLM QS 17 | DDC 611.0022/3—dc23 LC record available at https://lccn.loc.gov/2019058797 LC ebook record available at https://lccn.loc.gov/2019058798 Important note: Medicine is an ever-changing science undergoing continual development. Research and clinical experience are continually expanding our knowledge, in particular our knowledge of proper treatment and drug therapy. Insofar as this book mentions any dosage or ­application, readers may rest assured that the authors, editors, and publishers have made every effort to ensure that such references are in accordance with the state of knowledge at the time of production of the book. 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Rua do Matoso, 170 – Tijuca Rio de Janeiro RJ 20270-135 – Brasil +55 21 2563-9702 www.thiemerevinter.com.br Cover design: Thieme Publishing Group Printed in India by Replika Press Pvt. Ltd. ISBN 978-1-68420-203-4 Also available as an e-book: eISBN 978-1-68420-204-1 5 4 3 2 1 This book, including all parts thereof, is legally protected by copyright. Any use, exploitation, or commercialization outside the narrow limits set by copyright legislation without the publisher’s consent is illegal and liable to prosecution. This applies in particular to photostat reproduction, copying, mimeographing, preparation of microfilms, and electronic data processing and storage. Dedications To the thousands of former students who have populated every specialty and migrated to every corner of this country, while dedicating their careers to making life better for thousands more. I am inspired by their empathy and kindness, and grateful to have been a small part of their journey. And as always, to Colin and Bryan. Anne M. Gilroy To my friend and mentor Dr. Ken McFadden, who was responsible for my early training in gross anatomy and was a role model for success in teaching. I deeply appreciate the feedback I have received over the past 40 plus years from the thousands of students I have taught and who have made me an even better teacher. However, none of the success I have enjoyed in my life would have been possible without the constant support, assistance, and encouragement of my late wife, Cynthia Long. Brian R. MacPherson To my wife Jen and my son Quinn. Jamie C. Wikenheiser Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Preface to the First Edition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii Spinal Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spinal Cord Segments & Spinal Nerves . . . . . . . . . . . . . . . . . . Arteries & Veins of the Spinal Cord . . . . . . . . . . . . . . . . . . . . . Neurovascular Topography of the Back . . . . . . . . . . . . . . . . . . 40 42 44 46 Table of Contents Table of Contents 5 Sectional & Radiographic Anatomy Radiographic Anatomy of the Back (I) . . . . . . . . . . . . . . . . . . . 48 Radiographic Anatomy of the Back (II). . . . . . . . . . . . . . . . . . . 50 Back 1 Surface Anatomy Surface Anatomy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Bones, Ligaments & Joints Vertebral Column: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Vertebral Column: Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Cervical Vertebrae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Thoracic & Lumbar Vertebrae . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Sacrum & Coccyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intervertebral Disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Joints of the Vertebral Column: Overview . . . . . . . . . . . . . . . . 16 Joints of the Vertebral Column: Craniovertebral Region . . . . . 18 Vertebral Ligaments: Overview & Cervical Spine . . . . . . . . . . 20 Vertebral Ligaments: Thoracolumbar Spine . . . . . . . . . . . . . . 22 3 Muscles Muscles of the Back: Overview . . . . . . . . . . . . . . . . . . . . . . . . . Intrinsic Muscles of the Cervical Spine . . . . . . . . . . . . . . . . . . . Intrinsic Muscles of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 26 28 30 32 34 4 Neurovasculature Arteries & Veins of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Nerves of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Thorax 6 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 7 Thoracic Wall Thoracic Skeleton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sternum & Ribs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Thoracic Cage . . . . . . . . . . . . . . . . . . . . . . . . . . . Thoracic Wall Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Diaphragm . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Thoracic Wall . . . . . . . . . . . . . . . . . . . . Nerves of the Thoracic Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovascular Topography of the Thoracic Wall . . . . . . . . . . . Female Breast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Female Breast . . . . . . . . . . . . . . . . . . . . . . . 56 58 60 62 64 66 68 70 72 74 76 8 Thoracic Cavity Divisions of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . Arteries of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . Veins of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . Nerves of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . 78 80 82 84 86 vii Table of Contents 9 Mediastinum Mediastinum: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Mediastinum: Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Heart: Functions & Relations . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Pericardium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Heart: Surfaces & Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Heart: Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Arteries & Veins of the Heart . . . . . . . . . . . . . . . . . . . . . . . . . 100 Conduction & Innervation of the Heart . . . . . . . . . . . . . . . . . 102 Pre- & Postnatal Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Neurovasculature of the Esophagus . . . . . . . . . . . . . . . . . . . 108 Lymphatics of the Mediastinum . . . . . . . . . . . . . . . . . . . . . . . 110 112 114 116 118 120 122 124 126 128 11 Sectional & Radiographic Anatomy Sectional Anatomy of the Thorax . . . . . . . . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (I). . . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (II). . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (III). . . . . . . . . . . . . . . . 130 132 134 136 Abdomen 12 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 13 Abdominal Wall Bony Framework for the Abdominal Wall . . . . . . . . . . . . . . . 142 Muscles of the Anterolateral Abdominal Wall . . . . . . . . . . . . 144 viii 146 148 150 152 154 14 Abdominal Cavity & Spaces Divisions of the Abdominopelvic Cavity . . . . . . . . . . . . . . . . Peritoneum, Mesenteries & Omenta . . . . . . . . . . . . . . . . . . . Mesenteries & Peritoneal Recesses . . . . . . . . . . . . . . . . . . . . Lesser Omentum & Omental Bursa . . . . . . . . . . . . . . . . . . . . Mesenteries & Posterior Abdominal Wall. . . . . . . . . . . . . . . . 156 158 160 162 164 15 Internal Organs 10 Pulmonary Cavities Pulmonary Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pleura: Subdivisions, Recesses & Innervation . . . . . . . . . . . . Lungs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bronchopulmonary Segments of the Lungs . . . . . . . . . . . . . Trachea & Bronchial Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . Respiratory Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pulmonary Arteries & Veins . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Tracheobronchial Tree . . . . . . . . . . Lymphatics of the Pleural Cavity . . . . . . . . . . . . . . . . . . . . . . Rectus Sheath & Posterior Abdominal Wall . . . . . . . . . . . . . . Abdominal Wall Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . Inguinal Region & Canal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inguinal Region & Inguinal Hernias. . . . . . . . . . . . . . . . . . . . . Scrotum & Spermatic Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . Stomach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Duodenum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jejunum & Ileum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cecum, Appendix & Colon . . . . . . . . . . . . . . . . . . . . . . . . . . . Liver: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Liver: Lobes & Segments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gallbladder & Bile Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pancreas & Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kidneys & Suprarenal Glands (I) . . . . . . . . . . . . . . . . . . . . . . . Kidneys & Suprarenal Glands (II) . . . . . . . . . . . . . . . . . . . . . . 166 168 170 172 174 176 178 180 182 184 16 Neurovasculature Arteries of the Abdominal Wall & Organs . . . . . . . . . . . . . . . Abdominal Aorta & Renal Arteries . . . . . . . . . . . . . . . . . . . . . Celiac Trunk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superior & Inferior Mesenteric Arteries . . . . . . . . . . . . . . . . . Veins of the Abdominal Wall & Organs . . . . . . . . . . . . . . . . . Inferior Vena Cava & Renal Veins . . . . . . . . . . . . . . . . . . . . . . Portal Vein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superior & Inferior Mesenteric Veins . . . . . . . . . . . . . . . . . . . Lymphatics of the Abdominal Wall & Organs . . . . . . . . . . . . Lymph Nodes of the Posterior Abdominal Wall . . . . . . . . . . . Lymph Nodes of the Supracolic Organs . . . . . . . . . . . . . . . . . Lymph Nodes of the Infracolic Organs . . . . . . . . . . . . . . . . . . Nerves of the Abdominal Wall . . . . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation: Overview . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation & Referred Pain. . . . . . . . . . . . . . . . . Innervation of the Foregut & Urinary Organs . . . . . . . . . . . . Innervation of the Intestines . . . . . . . . . . . . . . . . . . . . . . . . . 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 17 Sectional & Radiographic Anatomy Sectional Anatomy of the Abdomen . . . . . . . . . . . . . . . . . . . 220 Radiographic Anatomy of the Abdomen (I). . . . . . . . . . . . . . 222 Radiographic Anatomy of the Abdomen (II). . . . . . . . . . . . . . 224 23 Sectional & Radiographic Anatomy Pelvis & Perineum Table of Contents Sectional Anatomy of the Pelvis & Perineum. . . . . . . . . . . . . 286 Radiographic Anatomy of the Female Pelvis. . . . . . . . . . . . . 288 Radiographic Anatomy of the Male Pelvis . . . . . . . . . . . . . . . 290 18 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 19 Bones, Ligaments & Muscles Pelvic Girdle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female & Male Pelvis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female & Male Pelvic Measurements . . . . . . . . . . . . . . . . . . . Pelvic Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Pelvic Floor & Perineum . . . . . . . . . . . . . . . . . Pelvic Floor & Perineal Muscle Facts. . . . . . . . . . . . . . . . . . . . 230 232 234 236 238 240 20 Spaces Contents of the Pelvis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Peritoneal Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Pelvis & Perineum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 21 Internal Organs Rectum & Anal Canal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ureters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Urinary Bladder & Urethra . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the Genital Organs . . . . . . . . . . . . . . . . . . . . . . . Uterus & Ovaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments & Fascia of the Deep Pelvis . . . . . . . . . . . . . . . . . . Vagina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female External Genitalia . . . . . . . . . . . . . . . . . . . . . . . . . . . . Penis, Testis & Epididymis . . . . . . . . . . . . . . . . . . . . . . . . . . . . Male Accessory Sex Glands. . . . . . . . . . . . . . . . . . . . . . . . . . . 248 250 252 254 256 258 260 262 264 266 22 Neurovasculature Overview of the Blood Supply to Pelvic Organs & Wall . . . . . Arteries & Veins of the Male Pelvis . . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Female Pelvis . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Rectum & External Genitalia . . . . . . . Lymphatics of the Pelvis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymph Nodes of the Genitalia. . . . . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation of the Genital Organs. . . . . . . . . . . . Autonomic Innervation of the Urinary Organs & Rectum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Male & Female Perineum . . . . . . . . 268 270 272 274 276 278 280 282 284 Upper Limb 24 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 25 Shoulder & Arm Bones of the Upper Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clavicle & Scapula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Humerus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Shoulder: Glenohumeral Joint . . . . . . . . . . . . . . Subacromial Space & Bursae . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Muscles of the Shoulder & Arm (I) . . . . . . . . . . . . . . Anterior Muscles of the Shoulder & Arm (II) . . . . . . . . . . . . . Posterior Muscles of the Shoulder & Arm (I) . . . . . . . . . . . . . Posterior Muscles of the Shoulder & Arm (II) . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (IV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 298 300 302 304 306 308 310 312 314 316 318 320 322 26 Elbow & Forearm Radius & Ulna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elbow Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments of the Elbow Joint . . . . . . . . . . . . . . . . . . . . . . . . . Radioulnar Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Forearm: Anterior Compartment . . . . . . . . . Muscles of the Forearm: Posterior Compartment . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 326 328 330 332 334 336 338 340 27 Wrist & Hand Bones of the Wrist & Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 Carpal Bones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344 Joints of the Wrist & Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . 346 ix Table of Contents Ligaments of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments & Compartments of the Wrist . . . . . . . . . . . . . . . Ligaments of the Fingers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Hand: Superficial & Middle Layers . . . . . . . . . Muscles of the Hand: Middle & Deep Layers . . . . . . . . . . . . . Dorsum of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 348 350 352 354 356 358 360 362 28 Neurovasculature Arteries of the Upper Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . Veins & Lymphatics of the Upper Limb . . . . . . . . . . . . . . . . . Nerves of the Upper Limb: Brachial Plexus . . . . . . . . . . . . . . Supraclavicular Branches & Posterior Cord . . . . . . . . . . . . . . Posterior Cord: Axillary & Radial Nerves . . . . . . . . . . . . . . . . Medial & Lateral Cords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Median & Ulnar Nerves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superficial Veins & Nerves of the Upper Limb . . . . . . . . . . . . Posterior Shoulder & Arm . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Axilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Arm & Cubital Region . . . . . . . . . . . . . . . . . . . . . . . . Anterior & Posterior Forearm . . . . . . . . . . . . . . . . . . . . . . . . . Carpal Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Palm of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dorsum of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364 366 368 370 372 374 376 378 380 382 384 386 388 390 392 394 396 398 400 402 404 Lower Limb 30 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408 31 Hip & Thigh Bones of the Lower Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 Femur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412 Hip Joint: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414 x 416 418 420 422 424 426 428 430 32 Knee & Leg 29 Sectional & Radiographic Anatomy Sectional Anatomy of the Upper Limb. . . . . . . . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (I). . . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (II). . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (III). . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (IV) . . . . . . . . . . . Hip Joint: Ligaments & Capsule . . . . . . . . . . . . . . . . . . . . . . . Anterior Muscles of the Hip, Thigh & Gluteal Region (I) . . . . Anterior Muscles of the Hip, Thigh & Gluteal Region (II) . . . Posterior Muscles of the Hip, Thigh & Gluteal Region (I) . . . Posterior Muscles of the Hip, Thigh & Gluteal Region (II) . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tibia & Fibula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint: Capsule, Ligaments & Bursae . . . . . . . . . . . . . . . Knee Joint: Ligaments & Menisci . . . . . . . . . . . . . . . . . . . . . . Cruciate Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Leg: Anterior & Lateral Compartments . . . . . Muscles of the Leg: Posterior Compartment . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432 434 436 438 440 442 444 446 448 450 33 Ankle & Foot Bones of the Foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments of the Ankle & Foot . . . . . . . . . . . . . . . . . . . . . . . . Plantar Vault & Arches of the Foot . . . . . . . . . . . . . . . . . . . . . Muscles of the Sole of the Foot . . . . . . . . . . . . . . . . . . . . . . . Muscles & Tendon Sheaths of the Foot . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 454 456 458 460 462 464 466 468 470 34 Neurovasculature Arteries of the Lower Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . 472 Veins & Lymphatics of the Lower Limb . . . . . . . . . . . . . . . . . 474 Lumbosacral Plexus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476 Nerves of the Lumbar Plexus . . . . . . . . . . . . . . . . . . . . . . . . . 478 Nerves of the Lumbar Plexus: Obturator & Femoral Nerves . 480 Nerves of the Sacral Plexus . . . . . . . . . . . . . . . . . . . . . . . . . . . 482 Nerves of the Sacral Plexus: Sciatic Nerve . . . . . . . . . . . . . . . 484 Superficial Nerves & Veins of the Lower Limb . . . . . . . . . . . . 486 Topography of the Inguinal Region . . . . . . . . . . . . . . . . . . . . 488 Topography of the Gluteal Region . . . . . . . . . . . . . . . . . . . . . 490 Topography of the Anterior, Medial & Posterior Thigh . . . . . 492 Topography of the Posterior Compartment of the Leg & Foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494 Topography of the Lateral & Anterior Compartments of the Leg & Dorsum of the Foot . . . . . . . . . . . . . . . . . . . . 496 Topography of the Sole of the Foot . . . . . . . . . . . . . . . . . . . . 498 35 Sectional & Radiographic Anatomy Sectional Anatomy of the Lower Limb . . . . . . . . . . . . . . . . . . 500 Radiographic Anatomy of the Lower Limb (I) . . . . . . . . . . . . 502 CN V: Trigeminal Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN VII: Facial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN VIII: Vestibulocochlear Nerve . . . . . . . . . . . . . . . . . . . . . . CN IX: Glossopharyngeal Nerve . . . . . . . . . . . . . . . . . . . . . . . CN X: Vagus Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN XI & XII: Accessory & Hypoglossal Nerves . . . . . . . . . . . . Autonomic Innervation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566 568 570 572 574 576 578 41 Neurovasculature of the Skull & Face Head & Neck 36 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512 37 Neck Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Innervation of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Larynx: Cartilage & Structure . . . . . . . . . . . . . . . . . . . . . . . . . Larynx: Muscles & Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Larynx, Thyroid & Parathyroids . . . Topography of the Neck: Regions & Fascia . . . . . . . . . . . . . . Topography of the Anterior Cervical Region . . . . . . . . . . . . . Topography of the Anterior & Lateral Cervical Regions . . . . Topography of the Lateral Cervical Region . . . . . . . . . . . . . . Topography of the Posterior Cervical Region . . . . . . . . . . . . 514 516 518 520 522 524 526 528 530 532 534 536 538 540 38 Bones of the Head Anterior & Lateral Skull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Posterior Skull & Calvaria . . . . . . . . . . . . . . . . . . . . . . . . . . . . Base of the Skull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovascular Pathways Exiting or Entering the Cranial Cavity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ethmoid & Sphenoid Bones . . . . . . . . . . . . . . . . . . . . . . . . . . 542 544 546 548 550 39 Muscles of the Skull & Face Muscles of Facial Expression & of Mastication . . . . . . . . . . . . Muscle Origins & Insertions on the Skull . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 554 556 558 40 Cranial Nerves Cranial Nerves: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 CN I & II: Olfactory & Optic Nerves . . . . . . . . . . . . . . . . . . . . 562 CN III, IV & VI: Oculomotor, Trochlear & Abducent Nerves . . . 564 Innervation of the Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arteries of the Head & Neck . . . . . . . . . . . . . . . . . . . . . . . . . . External Carotid Artery: Anterior, Medial & Posterior Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External Carotid Artery: Terminal Branches . . . . . . . . . . . . . . Veins of the Head & Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . Meninges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dural Sinuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Superficial Face . . . . . . . . . . . . . . . . . . . . Topography of the Parotid Region & Temporal Fossa . . . . . . Topography of the Infratemporal Fossa . . . . . . . . . . . . . . . . . Neurovasculature of the Infratemporal Fossa . . . . . . . . . . . . 580 582 Table of Contents Radiographic Anatomy of the Lower Limb (II) . . . . . . . . . . . . 504 Radiographic Anatomy of the Lower Limb (III). . . . . . . . . . . . 506 Radiographic Anatomy of the Lower Limb (IV). . . . . . . . . . . . 508 584 586 588 590 592 594 596 598 600 42 Orbit & Eye Bones of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Orbit & Eyelid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eyeball . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cornea, Iris & Lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602 604 606 608 610 612 614 43 Nasal Cavity & Nose Bones of the Nasal Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paranasal Air Sinuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Nasal Cavity . . . . . . . . . . . . . . . . . . Pterygopalatine Fossa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616 618 620 622 44 Temporal Bone & Ear Temporal Bone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External Ear & Auditory Canal . . . . . . . . . . . . . . . . . . . . . . . . . Middle Ear: Tympanic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . Middle Ear: Ossicular Chain & Tympanic Membrane . . . . . . . Arteries of the Middle Ear . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inner Ear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624 626 628 630 632 634 45 Oral Cavity & Pharynx Bones of the Oral Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporomandibular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oral Cavity Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Innervation of the Oral Cavity . . . . . . . . . . . . . . . . . . . . . . . . Tongue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Oral Cavity & Salivary Glands . . . . . . . . . 636 638 640 642 644 646 648 xi Table of Contents Tonsils & Pharynx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 Pharyngeal Muscles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 652 Neurovasculature of the Pharynx . . . . . . . . . . . . . . . . . . . . . . 654 46 Sectional & Radiographic Anatomy Sectional Anatomy of the Head & Neck (I). . . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (II) . . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (III). . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (IV). . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (V) . . . . . . . . . . . . . . Radiographic Anatomy of the Head & Neck (I). . . . . . . . . . . . Radiographic Anatomy of the Head & Neck (II). . . . . . . . . . . Radiographic Anatomy of the Head & Neck (III). . . . . . . . . . . 656 658 660 662 664 666 668 670 Brain, Macroscopic Organization . . . . . . . . . . . . . . . . . . . . . . Diencephalon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brainstem & Cerebellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ventricles & CSF Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 678 680 682 684 48 Blood Vessels of the Brain Veins & Venous Sinuses of the Brain . . . . . . . . . . . . . . . . . . . 686 Arteries of the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688 49 Functional Systems Anatomy & Organization of the Spinal Cord. . . . . . . . . . . . . . 690 Sensory & Motor Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . 692 50 Autonomic Nervous System Autonomic Nervous System (I): Overview . . . . . . . . . . . . . . . 694 Autonomic Nervous System (II) . . . . . . . . . . . . . . . . . . . . . . . 696 51 Sectional & Radiographic Anatomy Sectional Anatomy of the Nervous System . . . . . . . . . . . . . . 698 Radiographic Anatomy of the Nervous System . . . . . . . . . . . 700 Brain & Nervous System 47 Brain Nervous System: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 674 Nervous System: Development . . . . . . . . . . . . . . . . . . . . . . . 676 xii Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703 Acknowledgments We would like to thank the authors of the original award-winning Thieme Atlas of Anatomy three-volume series, Michael Schuenke, Erik Schulte, and Udo Schumacher, and the illustrators, Karl Wesker and Marcus Voll, for their work over the course of many years. We thank the many instructors, students, and translators for our non-English versions, who have taken the time to point out to us what we have done well and brought to our attention errors, ambiguities, and new information, or have suggested how we could present a topic more effectively. This input, combined with our experience teaching with the Atlas, have guided our work on this edition. We cordially thank the reviewers of the third edition, especially those who provided in-depth feedback: • Jennifer Brueckner-Collins, PhD University of Louisville School of Medicine Louisville, Kentucky • Luís Otávio Carvalho de Moraes, PhD Federal University of São Paulo São Paulo, Brazil • Jennifer Carr, PhD Salem State University Salem, Massachussetts • F. Baker Mills IV, MS (Class of 2021) University of South Carolina School of Medicine Columbia, South Carolina • C. Cem Denk, MD, PhD Hacettepe University Faculty of Medicine Ankara, Turkey • Stephen M. Novak, MD, JD Harvard University Cambridge, Massachusetts • Gary J. Farkas, PhD University of California, San Francisco School of Medicine San Francisco, California • Joy R. Patel (Class of 2021) NYIT College of Osteopathic Medicine Old Westbury, New York • Derek Harmon, PhD University of California, San Francisco School of Medicine San Francisco, California • Paisley Lynae Pauli, MHA (Class of 2021) University of the Incarnate Word School of Osteopathic Medicine San Antonio, Texas • Lindsey Kent (Class of 2020) West Virginia School of Osteopathic Medicine Lewisburg, West Virginia • Guenevere Rae, MS, PhD Tulane University School of Medicine New Orleans, Louisiana • Barbie Klein, PhD University of California, San Francisco School of Medicine San Francisco, California • Sherese Richards, MD The College of St. Scholastica Duluth, Minnesota • Nancy Lin (Class of 2021) CUNY School of Medicine New York, New York • William J. Swartz, PhD LSU Health Sciences Center New Orleans, Louisiana Foreword This Atlas of Anatomy, in my opinion, is the finest single-volume atlas of human anatomy that has ever been created. Two factors make it so: the images and the way they have been organized. The artists, Markus Voll and Karl Wesker, have created a new standard of excellence in anatomical art. Their graceful use of transparency and their sensitive representation of light and shadow give the reader an accurate three-dimensional understanding of every structure. The authors have organized the images so that they give just the flow of information a student needs to build up a clear mental image of the human body. Each two-page spread is a self-contained lesson that unobtrusively shows the hand of an experienced and thoughtful teacher. I wish I could have held this book in my hands when I was a student; I envy any student who does so now. Robert D. Acland, 1941–2016 Louisville, Kentucky December 2015 Preface In this new fourth edition of the Atlas of Anatomy, we are proud to offer what we believe is our best effort at presenting a clear and accurate story of human anatomy. A significant part of this effort is the addition of our newest co-author, Dr. Jamie C. Wikenheiser from the University of California, Irvine. Jamie’s love of anatomy, attention to detail, and proud background in teaching excellence in anatomy at all student levels makes him a highly qualified addition to the editorship of the Atlas that will ensure its continued development. As with previous editions, we have made every attempt to respond to the requests, comments, and critiques of our world-wide users. As always, we recognize that anatomy is a changing science. As concepts and terminology evolve, we feel a responsibility to pass this on and keep these aspects of the Atlas updated. Thus, our initial task for this edition was to update and further clarify the material already present in the Atlas. Among these modifications was a major revision of the many autonomic innervation wiring schematics. These are now uniformly designed to clearly differentiate between sympathetic and parasympathetic components and pre-and post-ganglionic fibers. We improved many tables by reorganizing and rewording the content and enlarging labels. Sectional and radiographic chapters in each unit, established in the third edition, have been expanded with more than forty additional MR and CT images, now accompanied, as are all sectional images throughout the Atlas, by new simplified navigators. Another focus of this edition was to provide more written and schematic-­ based information that addresses complex anatomic concepts. This includes new schematics that complement other images, expanded legends that accompany images, and most notably, the addition of almost thirty new clinical boxes (most with illustrations) in every unit. These focus on function, pathology, anatomic variations, clinical procedures, diagnostic techniques, embryological development, and aging. We continue to try to make difficult areas of anatomy more easily understood through better organization of chapter content and new diagrammatic approaches. The two-page spread that has been so popular in previous editions has been maintained in this edition, but an effort was made to improve their layouts by tabulating some content and adding more than 120 new illustrations and images. In this edition, the reader will notice major changes in two regions. In the abdomen and pelvic units, a greater focus is placed on the peritoneum, mesenteries, and peritoneal spaces. The inguinal region, a difficult area for students, is also expanded with new images and tables, as well as new and revised images of perineal structures. The head and neck unit is the second area of major revisions. In an effort to bring this material into alignment with the way it is usually encountered in the dissection lab, the chapter on the neck now precedes those on the head and includes new artwork that promotes the dissection views. Students will appreciate the reorgani­ zation and additional clarifying images of areas such as the cavernous sinus, pterygopalatine and infratemporal fossae, and oral and nasal cavities. Finally, a new expanded overview introduces the brain and nervous system chapter. As always, we are extremely grateful for the contributions of the many colleagues and reviewers who provide important feedback on earlier editions, alert us to inaccuracies and ambiguities, and share suggestions for new material. We recognize that our efforts, though important, are just one part of the process that brings this textbook to its final production. The entire Thieme Publishers team has encouraged and supported our efforts throughout this process. Our deep appreciation is extended to the most important contributors: Judith Tomat, Developmental Editor; Delia DeTurris, Acquisitions Editor, and Barbara Chernow, PhD, Production Manager, for their dedication and expertise in their respective fields and their confidence in our ability to produce a quality manuscript. Anne M. Gilroy Worcester, Massachusetts Brian R. MacPherson Lexington, Kentucky Jamie C. Wikenheiser Irvine, California December 2019 Preface to the First Edition Each of the authors was amazed and impressed with the extraordinary detail, accuracy, and beauty of the illustrations that were created for the Thieme Atlas of Anatomy. We feel these images are one of the most significant additions to anatomical education in the past 50 years. It was our intent to use these exceptional illustrations as the cornerstone of our effort in creating a concise single volume Atlas of Anatomy for the curious and eager health science student. Our challenge was first to select from this extensive collection those images that are most instructive and illustrative of current dissection approaches. Along the way, however, we realized that creating a single-volume atlas was much more than choosing images: each image has to convey a significant amount of detail while the appeal and labeling need to be clean and soothing to the eye. Therefore, hundreds of illustrations were drawn new or modified to fit the approach of this new atlas. In addition, key schematic diagrams and simplified summary-form tables were added wherever needed. Dozens of applicable radiographic images and important clinical correlates have been added where appropriate. Additionally, surface anatomy illustrations are accompanied by questions designed to direct the student’s attention to anatomic ­detail that is most relevant in conducting the physical exam. Elements from each of these features are arranged in a regional format to facilitate common dissection approaches. Within each region, the various components are examined systemically, followed by topographical images to tie the systems together within the region. In all of this, a clinical perspective on the anatomical structures is taken. The unique two facing pages “spread” format focuses the user to the area/topic being explored. We hope these efforts — the results of close to 100 combined years experience teaching the discipline of anatomy to bright, enthusiastic students — has resulted in a comprehensive, easy-to-use resource and reference. We would like to thank our colleagues at Thieme Publishers who so professionally facilitated this effort. We cannot thank enough­ Cathrin E. Schulz, MD, Editorial Director, Educational Products, who so graciously reminded us of deadlines, while always being available to “trouble shoot” problems. More importantly, she encouraged, helped, and complimented our efforts. We also wish to extend very special thanks and appreciation to Bridget Queenan, Developmental Editor, who edited and developed the manuscript with an outstanding talent for visualization and intuitive flow of information. We are very grateful to her for catching many details along the way while always patiently responding to requests for artwork and labeling changes. Cordial thanks to Elsie Starbecker, Senior Production Editor, who with great care and speed produced this atlas with its over 2,200 illustrations. Finally, thanks to Rebecca McTavish, Developmental Editor, for joining the team in the correction phase. So very much of their hard work has made the Atlas of Anatomy a reality. Anne M. Gilroy Worcester, Massachusetts Brian R. MacPherson Lexington, Kentucky Lawrence M. Ross Houston, Texas March 2008 Back 1 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Bones, Ligaments & Joints Vertebral Column: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Vertebral Column: Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Cervical Vertebrae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Thoracic & Lumbar Vertebrae . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Sacrum & Coccyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Intervertebral Disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Joints of the Vertebral Column: Overview . . . . . . . . . . . . . . . . 16 Joints of the Vertebral Column: Craniovertebral Region . . . . . 18 Vertebral Ligaments: Overview & Cervical Spine . . . . . . . . . . 20 Vertebral Ligaments: Thoracolumbar Spine . . . . . . . . . . . . . . 22 3 Muscles Muscles of the Back: Overview . . . . . . . . . . . . . . . . . . . . . . . . . Intrinsic Muscles of the Cervical Spine . . . . . . . . . . . . . . . . . . . Intrinsic Muscles of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 26 28 30 32 34 4 Neurovasculature Arteries & Veins of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . . Nerves of the Back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spinal Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spinal Cord Segments & Spinal Nerves . . . . . . . . . . . . . . . . . . Arteries & Veins of the Spinal Cord . . . . . . . . . . . . . . . . . . . . . Neurovascular Topography of the Back . . . . . . . . . . . . . . . . . . 36 38 40 42 44 46 5 Sectional & Radiographic Anatomy Radiographic Anatomy of the Back (I) . . . . . . . . . . . . . . . . . . . 48 Radiographic Anatomy of the Back (II). . . . . . . . . . . . . . . . . . . 50 1 Surface Anatomy Back Surface Anatomy Fig. 1.1 Palpable structures of the back Posterior view. Vertebra prominens (C7) Acromion Greater tubercle, humerus Scapular spine Medial border, scapula Inferior angle, scapula 6th through 12th ribs Iliac crest Anterior superior iliac spine Posterior superior iliac spine Sacrum Greater trochanter, femur Ischial tuberosity Trapezius Deltoid A Bony prominences. Teres major Teres minor Triceps brachii Latissimus dorsi External oblique Gluteus medius Gluteus maximus B Musculature. 2 Thoracolumbar fascia Fig. 1.2 Regions of the back and buttocks Posterior view. 1 Surface Anatomy Vertebral region Suprascapular region Deltoid region Scapular region Interscapular region Lateral pectoral region Fig. 1.3 Spinous processes and landmarks of the back Posterior view. Infrascapular region C7 spinous process (vertebra prominens) Lumbar triangle Cervicothoracic junction Sacral region T3 spinous process Gluteal region Anal region Scapular spine T7 spinous process Inferior angle of scapula T12 spinous process Paravertebral Scapular line line 12th rib Posterior midline L4 spinous process Iliac crest Posterior superior iliac spine S2 spinous process Table 1.2 Table 1.1 Posterior midline Reference lines of the back Posterior trunk midline at the level of the spinous processes Paravertebral line Line at the level of the transverse processes Scapular line Line through the inferior angle of the scapula Spinous processes that provide useful posterior landmarks Vertebral spinous process Posterior landmark C7 Vertebra prominens (the projecting spinous process of C7 is clearly visible and palpable) T3 The scapular spine T7 The inferior angle of the scapula T12 Just below the 12th rib L4 The summit of the iliac crest S2 The posterior superior iliac spine (recognized by small skin depressions directly over the iliac spines) 3 2 Bones, Ligaments & Joints Back Vertebral Column: Overview The vertebral column (spine) is divided into four regions: the cervical, thoracic, lumbar, and sacral spines. Both the cervical and lumbar spines demonstrate lordosis (inward curvature); the thoracic and sacral spines demonstrate kyphosis (outward curvature). Fig. 2.1 Vertebral column Left lateral view. Craniocervical junction Cervical spine C1–C7 vertebrae Cervicothoracic junction Spinous process Thoracic spine Thoracolumbar junction Lumbar spine Lumbosacral junction T1–T12 vertebrae Costal facets Articular processes Sacrum (sacral spine) A Regions of the spine. Intervertebral foramina Clinical box 2.1 L1–L5 vertebrae Spinal development The characteristic curvatures of the adult spine appear over the course of postnatal development, being only partially present in a newborn. The newborn has a “kyphotic” spinal curvature (A); lumbar lordosis develops later and becomes stable at puberty (C). Intervertebral disk Adult spinal column Kyphotic spine of the newborn Transitional phase Sacral promontory Cervical lordosis Thoracic kyphosis Lumbar lordosis Sacral kyphosis A 4 B C Sacrum (S1–S5 vertebrae) Coccyx B Bony vertebral column. Fig. 2.2 Normal anatomical position of the spine Left lateral view. Larynx Spinous process of vertebra prominens (C7) Trachea Inflection points Line of gravity Spinal cord Ascending aorta Heart Esophagus Diaphragm Vertebral canal Intervertebral disk Spinous process Liver Body of L1 Conus medullaris Stomach Whole-body center of gravity 2 Bones, Ligaments & Joints Dens of axis (C2) Dens of axis (C2) Tongue External auditory canal Abdominal aorta Cauda equina Sacral promontory A Line of gravity. The line of gravity passes through certain anatomical landmarks, including the inflection points at the cervicothoracic and thoracolumbar junctions. It continues through the center of gravity (anterior to the sacral promontory) before passing through the hip joint, knee, and ankle. Bladder Coccyx Rectum B Midsagittal section through an adult male. Clinical box 2.2 Abnormal Vertebral Column Curvatures Scoliotic curve A Normal BExcessive kyphosis C Excessive lordosis Asymmetrical waistline D Scoliosis E Right convex thoracic scoliosis 5 Back Vertebral Column: Elements Fig. 2.3 Bones of the vertebral column The transverse processes of the lumbar vertebrae are originally rib rudiments and so are named costal processes. Atlas (C1) Axis (C2) Atlas (C1) Dens of axis (C2) C1—C7 vertebrae Transverse processes T1—T12 vertebrae Vertebra prominens (C7) Spinous processes Transverse processes Vertebral body Intervertebral disk L1 Costal processes L1—L5 vertebrae Sacrum (fused S1—S5 vertebrae) Coccyx (Co1—Co4 vertebrae) A Anterior view. 6 Sacrum Anterior sacral foramina Coccyx B Posterior view. Posterior sacral foramina Fig. 2.4 Structural elements of a vertebra Fig. 2.5 Typical vertebrae Superior articular process Vertebral body Vertebral arch Superior view. Vertebral foramen Lamina Vertebral arch Transverse process Pedicle Lamina Spinous process Superior articular facet Pedicle Posterior tubercle Transverse process with groove for spinal n. Spinous process Transverse foramen Body Inferior articular process Anterior tubercle A Cervical vertebra (C4). 2 Bones, Ligaments & Joints Left posterosuperior view. With the exception of the atlas (C1) and axis (C2), all vertebrae consist of the same structural elements. Spinous process Costal facet Lamina Transverse process Pedicle Superior articular facet Inferior costal facet Superior costal facet Body Median sacral crest B Thoracic vertebra (T6). Spinous process Accessory process Sacral canal Superior articular process Superior articular facet Transverse process Vertebral arch Lateral part of sacrum Superior articular process Vertebral foramen Superior vertebral notch Body Base of Promontory sacrum C Lumbar vertebra (L4). Table 2.1 Wing of sacrum D Sacrum. Structural elements of vertebrae Vertebrae Body Cervical vertebrae C3*–C7 Small (kidney-shaped) Thoracic vertebrae T1–T12 Medium (heartshaped); includes costal facets Vertebral foramen Transverse processes Articular processes Spinous process Large (triangular) Small (may be absent on C7); anterior and posterior tubercles enclose transverse foramen Superoposteriorly and inferoanteriorly; oblique facets: most nearly horizontal Short (C3–C5); bifid (C3–C6); long (C7) Small (circular) Large and strong; length decreases T1–T12; costal facets (T1–T10) Posteriorly (slightly laterally) and anteriorly (slightly medially); facets in coronal plane Long, sloping posteroinferiorly; tip extends to level of vertebral body below Posteromedially (or medially) and anterolaterally (or laterally); facets nearly in sagittal plane; mammillary process on posterior surface of each superior articular process Short and broad Superoposteriorly (SI) superior surface of lateral sacrumauricular surface Median sacral crest Lumbar vertebrae L1–L5 Large (kidney-shaped) Medium (triangular) Called costal processes, long and slender; accessory process on posterior surface Sacral vertebrae (sacrum) S1–S5 (fused) Decreases from base to apex Sacral canal Fused to rudimentary rib (ribs, see pp. 56–59) *C1 (atlas) and C2 (axis) are considered atypical (see pp. 8–9). 7 Back Cervical Vertebrae The seven vertebrae of the cervical spine differ most conspicuously from the common vertebral morphology. They are specialized to bear the weight of the head and allow the neck to move in all directions. C1 and C2 are known as the atlas and axis, respectively. C7 is called the vertebra prominens for its long, palpable spinous ­process. Fig. 2.6 Cervical spine Left lateral view. Posterior arch of atlas Anterior tubercle Posterior tubercle C1 (atlas) C2 (axis) Spinous process Groove for spinal n. Vertebral body Zygapophyseal joint Anterior tubercle Fig. 2.7 Atlas (C1) Posterior tubercle Anterior tubercle Transverse foramen Inferior articular process Posterior tubercle Superior articular process Groove for spinal n. Uncovertebral joint Groove for vertebral a. Superior articular facet Posterior arch of atlas Transverse process Inferior articular facet A Left lateral view. Fig. 2.8 Axis (C2) Spinous process Uncinate process Anterior articular facet Superior articular facet C7 (vertebra prominens) Transverse process Dens Posterior articular facet Spinous process Transverse foramen Transverse foramen Body A Bones of the cervical spine, left lateral view. Transverse process Inferior articular facet Vertebral arch A Left lateral view. C1 (atlas) Fig. 2.9 Typical cervical vertebra (C4) C2 (axis) Transverse foramen Superior articular process Transverse process Superior articular facet Body Inferior articular process C7 spinous process Groove for spinal n. B Radiograph of the cervical spine, left lateral view. 8 A Left lateral view. Inferior articular facet Spinous process Clinical box 2.3 The cervical spine is prone to hyperextension injuries, such as “whiplash,” which can occur when the head extends back much farther than it normally would. The most common injuries of the cervical spine are fractures of the dens of the axis, traumatic spondylolisthesis (anterior slippage of a vertebral body), and atlas fractures. Patient prognosis is largely dependent on the spinal level of the injuries (see p. 42). Superior articular facet Spinous process of C1 Anterior displacement of body of C2 vertebra Spinous process of C2 Fractured vertebral arch of C2 Vertebral body of C3 Anterior arch Posterior tubercle Posterior arch Superior articular facet This patient hit the dashboard of his car while not wearing a seat belt. The resulting hyperextension caused the traumatic spondylolisthesis of C2 (axis) with fracture of the vertebral arch of C2, as well as tearing of the ligaments between C2 and C3. This injury is often referred to as “hangman’s fracture.” 2 Bones, Ligaments & Joints Injuries in the cervical spine Groove for vertebral a. Lateral masses Transverse process Transverse foramen Transverse foramen Inferior articular facet Anterior tubercle Transverse process B Anterior view. Anterior arch Anterior tubercle C Superior view. Spinous process Anterior articular facet Dens Vertebral foramen Superior articular facet Vertebral arch Inferior articular process Dens Transverse process Body Transverse process Superior articular facet Inferior articular facet B Anterior view. Transverse foramen Anterior articular facet C Superior view. Uncinate process Superior articular process Posterior tubercle Groove for spinal n. Anterior tubercle Body Spinous process B Anterior view. Facet for dens Inferior articular facet Vertebral foramen Spinous process Vertebral arch Lamina Transverse process Superior articular facet Pedicle Transverse process with groove for spinal n. Posterior tubercle Body Transverse foramen Anterior tubercle C Superior view. 9 Back Thoracic & Lumbar Vertebrae Fig. 2.10 Thoracic spine Left lateral view. Fig. 2.11 Typical thoracic vertebra (T6) Spinous process Superior vertebral notch 1st thoracic vertebra (T1) Superior costal facet Inferior articular process Superior articular process Superior articular facet Transverse process Costal facet on transverse process Body Inferior vertebral notch Transverse process Inferior costal facet Superior costal facet Inferior costal facet Costal facet on transverse process Zygapophyseal joint Inferior articular facet Spinous process A Left lateral view. Superior articular process Transverse process Body Vertebral body Superior costal facet Intervertebral foramen Inferior vertebral notch Superior vertebral notch 12th thoracic vertebra (T12) Inferior costal facet Costal facet on transverse process Spinous process Inferior articular facet B Anterior view. Costal facet on transverse process Spinous process Lamina Inferior articular facet Transverse process Pedicle Inferior costal facet Superior vertebral notch Superior costal facet Body C Superior view. 10 Superior articular facet Fig. 2.12 Lumbar spine Left lateral view. Superior articular process Superior articular process Transverse process Mammillary process Intervertebral foramen Inferior vertebral notch Transverse process Body Spinous process Spinous process Superior vertebral notch Inferior vertebral notch Zygapophyseal joint Inferior articular process Vertebral body 5th lumbar vertebra (L5) Inferior articular facet 2 Bones, Ligaments & Joints 1st lumbar vertebra (L1) Fig. 2.13 Typical lumbar vertebra (L4) A Left lateral view. Inferior articular facet Inferior articular process Body Superior articular process Transverse process Clinical box 2.4 Osteoporosis The spine is the structure most affected by degenerative diseases of the skeleton, such as arthrosis and osteoporosis. In osteoporosis, more bone material gets reabsorbed than built up, resulting in a loss of bone mass. Symptoms include compression fractures and resulting back pain. Inferior articular facet Inferior articular process Spinous process B Anterior view. Spinous process Accessory process Vertebral arch Vertebral foramen Body A Radiograph of a normal lumbar spine, left lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) B Radiograph of an osteoporotic lumbar spine with a compression fracture at L1 (arrow). Note that the vertebral bodies are decreased in density, and the internal trabecular structure is coarse. (Reproduced from Jallo J, Vaccaro AR. Neurotrauma and Critical Care of the Spine, 1st ed. New York, NY: Thieme; 2009.) Superior articular facet Mammillary process Transverse process Superior articular process Superior vertebral notch C Superior view. 11 Back Sacrum & Coccyx The sacrum is formed from five postnatally fused sacral vertebrae. The base of the sacrum articulates with the 5th lumbar vertebra, and the apex articulates with the coccyx, a series of three or four rudimentary vertebrae. See Fig. 19.1, p. 230. Fig. 2.14 Sacrum and coccyx Promontory Superior articular process Wing of sacrum Lateral part Transverse lines Anterior sacral foramina Apex of sacrum Superior articular facet Sacrococcygeal joint Sacral tuberosity Sacral canal Coccyx A Anterior view. Lateral part Auricular surface Lateral sacral crest Median sacral crest Posterior sacral foramina Medial sacral crest Sacral hiatus Coccygeal cornu Coccyx B Posterior view. 12 Sacral cornua Sacrococcygeal joint Superior articular process Sacral promontory Sacral promontory Auricular surface Sacral tuberosity Sacroiliac joint 2 Bones, Ligaments & Joints Base of sacrum Posterior surface Anterior (pelvic) surface Lateral sacral crest DRadiograph of sacrum, anteroposterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Coccyx C Left lateral view. Fig. 2.15 Sacrum Superior view. Median sacral crest Median Superior sacral crest articular process Sacral canal Lateral part of sacrum Sacral canal Posterior sacral foramen Lateral part Promontory Wing of sacrum Pelvic surface Anterior sacral foramen Coccyx A Base of sacrum, superior view. Transverse section through second sacral vertebra demonstrating B anterior and posterior sacral foramina, superior view. 13 Back Intervertebral Disks Fig. 2.16 Intervertebral disk in the vertebral column Vertebral canal Midsagittal section of T11–T12, left lateral view. The intervertebral disks occupy the spaces between vertebrae (intervertebral joints, see p. 16). Vertebral body Intervertebral disk Superior articular facet Anulus fibrosus Vertebral arch Nucleus pulposus Spinous process Ligamentum flavum Interspinous lig. Anulus fibrosus Fig. 2.17 Structure of intervertebral disk Nucleus pulposus Superior articular process Transverse process Anterosuperior view with the anterior half of the disk and the right half of the end plate removed. The intervertebral disk consists of an external fibrous ring (anulus fibrosus) and a gelatinous core (nucleus pulposus). Hyaline cartilage end plate Intervertebral surface Fig. 2.18 Relation of intervertebral disk to vertebral canal Body Marginal ridge (epiphyseal ring) Fig. 2.19 Outer zone of the annulus fibrosus Anterior view of L3–L4 with intervertebral disk. Fourth lumbar vertebra, superior view. Marginal ridge (epiphyseal ring) Spinous process Vertebral foramen Superior vertebral notch Superior articular process Superior articular process Transverse process Transverse process Intervertebral foramen Vertebral bodies Crossing fiber systems of the anulus fibrosus Nucleus pulposus Anulus fibrosus Inner zone Outer zone Inferior articular process 14 Spinous process Clinical box 2.5 As the stress resistance of the anulus fibrosus declines with age, the tissue of the nucleus pulposus may protrude through weak spots under loading. If the fibrous ring of the anulus ruptures completely, the herniated material may compress the contents of the intervertebral foramen (nerve roots and blood vessels—see posterolateral herniation below). These patients often suffer from severe local back pain. Pain is also felt in the associated dermatome (see p. 42). When the motor part of the spinal nerve is affected, the muscles served by that spinal nerve will show weakening. It is an important diagnostic step to test the muscles innervated by a nerve from a certain spinal segment, as well as the sensitivity in the specific dermatome. Example: The first sacral nerve root innervates the gastrocnemius and soleus muscles; thus, standing or walking on toes can be affected (see p. 446). Cauda equina Epidural fat Fat in the epidural space L3 Intervertebral foramen Dural sleeve with spinal n. Herniated disk Cauda equina in CSF*-filled dural sac L4 Central herniation Sacrum Nucleus pulposus A Superior view. B Midsagittal T2-weighted MRI (magnetic resonance image). Posterior herniation (A, B) In the MRI, a conspicuously herniated disk at the level of L3–L4 protrudes posteriorly (transligamentous herniation). The dural sac is deeply indented at that level. *CSF (cerebrospinal fluid). Spinal dura mater Dural sac Spondylophyte Dural sleeve with spinal n. Compressed nerve roots Posterolateral herniation Posterolateral herniation Nucleus pulposus Intervertebral disk Pedicle (cut surface) Dural sleeve with spinal n. C Superior view. Posterolateral herniation (C, D) A posterolateral herniation may compress the spinal nerve as it passes through the intervertebral foramen. If more Bone drill 2 Bones, Ligaments & Joints Disk herniation in the lumbar spine D Posterior view, vertebral arches removed. medially positioned, the herniation may spare the nerve at that level but impact nerves at inferior levels. Microsurgical instrument L3 Herniated disc L4 L5 S1 E Microdiscectomy surgery (E, F) is performed in order to remove a portion of a ­herniated disc that is irritating the nerve root. Through a small incision, the erector spinae muscles are reflected laterally to expose the ligamentum flavum, which is then removed in order to access the nerve roots in F Compressed nerve the ­spinal canal. A small portion of the facet joint may be ­removed to both facilitate access and relieve pressure on the nerve roots. Only the herniated portion of the disk is removed with the remaining tissue left intact. 15 Back Joints of the Vertebral Column: Overview Table 2.2 Joints of the vertebral column ① Craniovertebral joints ① Atlanto-occipital joints Occiput–C1 ② Atlantoaxial joints C1–C2 Joints of the vertebral bodies ② ③ Uncovertebral joints C3–C7 ④ Intervertebral joints C2–S1 Joints of the vertebral arch ⑤ Zygapophyseal joints C2–S1 ③ Fig. 2.20 Zygapophyseal (intervertebral facet) joints The orientation of the zygapophyseal joints differs between the spinal regions, influencing the degree and direction of movement. ⑤ Transverse process Superior articular process Anterior tubercle Spinous process Posterior tubercle Zygapophyseal joint Groove for spinal n. ④ Transverse foramen Inferior articular process A Cervical region, left lateral view. The zygapophyseal joints lie 45 degrees from the horizontal. Superior articular facet Vertebral foramen Costal facet Superior articular process Transverse process Zygapophyseal joint Zygapophyseal joint Transverse process Inferior articular facet B Thoracic region, left lateral view. The joints lie in the coronal plane. 16 Spinous process Inferior articular process C Lumbar region, posterior view. The joints lie in the sagittal plane. Fig. 2.21 Uncovertebral joints Dens Lateral atlantoaxial joint Atlas (C1) Clinical box 2.6 Proximity of the spinal nerve and vertebral artery to the uncinate process The spinal nerve and vertebral artery pass through the intervertebral and transverse foramina, respectively (A and B). Bony outgrowths (osteophytes) on the uncinate process (C) resulting from uncovertebral arthrosis (degeneration) may compress both the nerve and the artery and can lead to chronic pain in the cervical region. Vertebral a. in transverse foramen Axis (C2) C1 spinal n. Atlas (C1) Axis (C2) Uncinate processes Vertebral a. Vertebral body Transverse process Posterior tubercle Anterior tubercle 2 Bones, Ligaments & Joints Anterior view. Uncovertebral joints form during childhood between the uncinate processes of C3–C7 and the vertebral bodies immediately superior. The joints may result from fissures in the cartilage of the disks that assume an articular character. If the fissures become complete tears, the risk of nucleus pulposus herniation is increased (see p. 15). Uncinate processes Intervertebral disk Groove for spinal n. Transverse process Spinal n. in groove C7 spinal n. Vertebral body (C7) Inferior articular facet A Cervical spine, anterior view. Spinous process A Uncovertebral joints in the cervical spine of an 18-year-old man, anterior view. Vertebral foramen Lamina Spinal cord Anulus fibrosus Superior articular facet Spinal n. Posterior root (spinal) ganglion Nucleus pulposus Transverse Vertebral process body Transverse Uncinate foramen process Vertebral a. B Uncovertebral joint (enlarged), anterior view of coronal section. B Fourth cervical vertebra, superior view. Spinous process Spondylophytes Inferior articular process Uncovertebral joint Superior articular facet Transverse foramen Vertebral body C Uncovertebral joints, split intervertebral disks, anterior view of coronal section. Uncinate process Advanced uncovertebral arthrosis of the C fourth cervical vertebra, superior view. 17 Back Joints of the Vertebral Column: Craniovertebral Region Fig. 2.22 Craniovertebral joints Superior nuchal line External occipital protuberance Occipital condyle Mastoid process (temporal bone) Dens of axis (C2) Atlas (C1) Styloid process (temporal bone) Median atlantoaxial joint Axis (C2) Superior articular facet (lateral mass of atlas) Dens of axis (C2) A Posterior view. Groove for vertebral a. Transverse process Fig. 2.23 Ligaments of the craniovertebral joints Spinous process Median atlantoaxial joint Anterior tubercle Superior articular facet B Atlas and axis, posterosuperior view. Alar ligs. Apical lig. of the dens Transverse lig. of atlas Transverse process Dens Lateral mass of the atlas Vertebral foramen Longitudinal fascicles Posterior tubercle of the atlas A Ligaments of the median atlantoaxial joint, superior view. The fovea of the atlas is hidden by the joint capsule. Spinous process of axis Alar ligs. Longitudinal fascicles Apical lig. of the dens Superior articular facet Tectorial membrane Transverse lig. of atlas Capsule of lateral atlantooccipital joint Transverse process Intertransverse lig. Groove for vertebral a. Posterior atlanto-occipital membrane Posterior arch of atlas Nuchal lig. Spinous process B Ligaments of the craniovertebral joints, posterosuperior view. The dens of the axis is hidden by the tectorial membrane. 18 the two lateral and one medial articulations between the atlas (C1) and axis (C2). Fig. 2.24 Dissection of the craniovertebral joint ligaments External occipital protuberance Nuchal lig. 2 Bones, Ligaments & Joints The atlanto-occipital joints are the two articulations between the convex occipital condyles of the occipital bone and the slightly concave superior articular facets of the atlas (C1). The atlantoaxial joints are Styloid process Posterior atlantooccipital membrane Atlas (C1) Lateral atlantoaxial joint (capsule) Nuchal lig. Axis (C2) Ligamentum flavum Atlanto-occipital joint A Nuchal ligament and posterior atlantooccipital membrane. Posterior atlantooccipital membrane Posterior arch of atlas Tectorial membrane (posterior longitudinal lig.) Spinous process Vertebral arch Alar ligs. B Posterior longitudinal ligament. Removed: Spinal cord; vertebral canal windowed. Atlantooccipital capsule Longitudinal fascicles* Apical lig. of dens Transverse lig. of atlas* Posterior longitudinal lig. C Cruciform ligament of atlas (*). Removed: Tectorial membrane, posterior atlantooccipital membrane, and vertebral arches. Alar lig. Lateral mass of C1 Dens, posterior articular surface DAlar and apical ligaments. Removed: Transverse ligament of atlas. 19 Back Vertebral Ligaments: Overview & Cervical Spine The ligaments of the spinal column bind the vertebrae and enable the spine to withstand high mechanical loads and shearing stresses and limit the range of motion. The ligaments are subdivided into vertebral body ligaments and vertebral arch ligaments. Fig. 2.25 Vertebral ligaments Viewed obliquely from the left posterior view. A Anterior longitudinal lig. Table 2.3 Transverse process Vertebral ligaments Ligament Location Vertebral body ligaments P Posterior longitudinal lig. Inter- ④ transverse lig. Pedicle Vertebral arch Lamina Inferior articular process Supraspinous lig. Superior articular process ① Ligamentum flavum Interspinous lig. ③ Spinous process ② A Anterior longitudinal lig. Along anterior surface of vertebral body P Posterior longitudinal lig. Along posterior surface of vertebral body Vertebral arch ligaments ① Ligamentum flavum Between laminae ② Interspinous lig. Between spinous process ③ Supraspinous lig. Along posterior ridge of spinous processes ④ Intertransverse lig. Between transverse processes Nuchal lig.* Between external occipital protuberance and spinous process of C7 *Corresponds to a supraspinous ligament that is broadened superiorly. Fig. 2.26 Anterior longitudinal ligament Fig. 2.27 Posterior longitudinal ligament Anterior view with base of skull removed. Internal occipital protuberance Atlanto-occipital joint (atlantooccipital capsule) Atlas (C1) Transverse foramina Axis (C2) Anterior longitudinal lig. Groove for spinal nerve Intervertebral disk 20 Posterior view with vertebral canal opened via laminectomy and spinal cord removed. The tectorial membrane is a broadened expansion of the posterior longitudinal ligament. External occipital protuberance Occipital bone, basilar part Anterior atlantooccipital membrane Transverse process Lateral atlantoaxial joint (capsule) Zygapophyseal joint (capsule) Posterior tubercle Atlanto-occipital capsule Posterior atlantooccipital membrane Atlanto-occipital joint Tectorial membrane Vertebral arch Anterior tubercle Vertebra prominens (C7) Posterior longitudinal lig. Fig. 2.28 Ligaments of the cervical spine Sella turcica Apical lig. of the dens Hypoglossal canal Tectorial membrane Mid-sagittal view. Occipital bone, basilar part External occipital protuberance Anterior atlanto-occipital membrane Anterior arch of atlas (C1) Maxilla Dens of axis (C2) Longitudinal fascicles Posterior arch of atlas, posterior tubercle Zygapophyseal joint capsule Intervertebral disk Anterior longitudinal lig. Posterior longitudinal lig. Transverse lig. of atlas Posterior atlanto-occipital membrane 2 Bones, Ligaments & Joints Sphenoid sinus Nuchal lig. Ligamenta flava Vertebral arch Intervertebral foramen Spinous process Interspinous lig. Supraspinous lig. C7 vertebral body (vertebra prominens) A Midsagittal section, left lateral view. The nuchal ligament is the broadened, sagittally oriented part of the supraspinous ligament that extends from the vertebra prominens (C7) to the external occipital protuberance. Apex of dens Body of axis Cerebellomedullary cistern Posterior tubercle of atlas Nuchal lig. Posterior longitudinal lig. Vertebral body Intervertebral disk Supraspinous lig. Vertebra prominens (C7) Anterior longitudinal lig. Spinal cord Subarachnoid space B Midsagittal T2-weighted MRI, left lateral view. 21 Back Vertebral Ligaments: Thoracolumbar Spine Fig. 2.29 Ligaments of the vertebral column: Thoracolumbar junction Vertebral canal Left lateral view of T11–L3, with T11–T12 sectioned in the midsagittal plane. Intervertebral disk Superior articular facet Posterior longitudinal lig. Anulus fibrosus Vertebral arch Nucleus pulposus Ligamenta flava Superior articular process Anterior longitudinal lig. Spinous processes Interspinous ligs. Transverse process Vertebral body Intertransverse ligs. Zygapophyseal joint capsule Supraspinous lig. Inferior articular facet Clinical box 2.7 Spinal fusion procedure Spinal fusion is a surgical procedure used to restore stability to the vertebral column or to eliminate painful motion. The basic idea involves fusing two or more vertebrae so they will heal into a single, solid bone. Fusions can take place at any part of the vertebral column. A Midline cutaway 22 B Posterior view Fig. 2.30 Anterior longitudinal ligament Anterior view of L3–L5. 2 Bones, Ligaments & Joints Transverse process Intervertebral disk Vertebral body Fig. 2.31 Ligamenta flava and intertransverse ligaments Anterior view of opened vertebral canal at level of L2–L5. Removed: L2–L4 vertebral bodies. Superior articular process Lamina Anterior longitudinal lig. Fig. 2.32 Posterior longitudinal ligament Intertransverse ligs. Posterior view of opened vertebral canal at level of L2–L5. Removed: L2–L4 vertebral arches at pedicular level. Ligamenta flava Transverse process Nutrient foramina Pedicles (cut) of vertebral arches Posterior longitudinal lig. Posterior longitudinal lig. Superior articular process Anterior longitudinal lig. Inferior articular facet Intervertebral foramen Intervertebral disk Vertebral body Gap in ligamentous reinforcement of the disk Spinous process Superior articular facet Transverse process Inferior articular process Spinous process Vertebral canal 23 3 Muscles Back Muscles of the Back: Overview The muscles of the back are divided into two groups, the ex­trinsic and the intrinsic muscles, which are separated by the p ­ osterior layer of the thoracolumbar fascia. The superficial extrinsic muscles are considered muscles of the upper limb that have migrated to the back; these muscles are discussed in the Upper Limb, pp. 312–317. Fig. 3.1 Superficial extrinsic muscles of the back Posterior view. Removed: Trapezius and latissimus dorsi (right). Revealed: Thoracolumbar fascia. Note: The posterior layer of the thoracolumbar fascia is reinforced by the aponeurotic origin of the latissimus dorsi. Sternocleidomastoid Thoracolumbar fascia (= deep layer of nuchal fascia) Trapezius (descending part) Trapezius (transverse part) Rhomboid minor Levator scapulae Clavicle Acromion Scapular spine Supraspinatus Rhomboid major Deltoid Infraspinatus Scapula, medial border Teres major Teres major Trapezius (ascending part) Serratus anterior Triceps brachii Latissimus dorsi (cut) Latissimus dorsi Serratus posterior inferior Thoracolumbar fascia, posterior layer External oblique Olecranon Aponeurotic origin of latissimus dorsi Internal oblique Lumbar triangle, internal oblique Iliac crest Gluteal aponeurosis 24 Gluteus maximus Fig. 3.2 Thoracolumbar fascia Infrahyoid muscles Trachea 3 Muscles and middle layer that unite at the lateral margin of the intrinsic back muscles. In the neck, the posterior layer blends with the nuchal fascia (deep layer), becoming continuous with the deep cervical fascia (prevertebral layer). Transverse section, superior view. The intrinsic back muscles are sequestered in an osseofibrous canal, formed by the thoracolumbar fascia, the vertebral arches, and the spinous and transverse processes of associated vertebrae. The thoracolumbar fascia consists of a posterior Pretracheal Esophagus visceral layer A Thyroid gland Sternocleidomastoid Pretracheal muscular layer Investing (superficial) layer Internal jugular v. Carotid sheath Deep cervical fascia B Prevertebral layer Vagus n. Common carotid a. Longus colli Scalene muscles Brachial plexus C6 vertebra Spinal cord Levator scapulae Intrinsic back muscles Trapezius Deep layer Superficial layer Nuchal fascia A Transverse section at level of C6 vertebra, superior view. Psoas fascia Abdominal aorta Inferior vena cava Parietal peritoneum Kidney Renal fascia, anterior layer Lateral abdominal wall muscles Transversalis fascia L2 vertebra Fibrous capsule Psoas major Renal fascia, posterior layer Latissimus dorsi Vertebral arch Serratus posterior inferior Transverse process of L2 Quadratus lumborum Spinous process of L1 Intrinsic back muscles Middle layer Posterior layer Anterior layer (quadratus lumborum fascia) Thoracolumbar fascia B Transverse section at level of L2, superior view. Removed: Cauda equina and anterior trunk wall. 25 Back Intrinsic Muscles of the Cervical Spine Fig. 3.3 Muscles in the nuchal region Posterior view. Removed: Trapezius, sternocleidomastoid, splenius, and semispinalis muscles (right). Revealed: Nuchal muscles (right). Parietal bone Occipital bone External occipital protuberance Semispinalis capitis Sternocleidomastoid Superior nuchal line Splenius capitis Semispinalis capitis Sternocleidomastoid Mastoid process Obliquus capitis superior Atlas (C1), transverse process Rectus capitis posterior minor Rectus capitis posterior major Obliquus capitis inferior Longissimus capitis Splenius capitis Axis (C2), spinous process 26 Semispinalis capitis Semispinalis cervicis Splenius capitis Trapezius Splenius cervicis Fig. 3.4 Short nuchal muscles Posterior view. See Fig. 3.6. Three of the short nuchal muscles (obliquus capitis inferior, obliquus capitis superior and the rectus capitis posterior major) form the boundaries of the suboccipital triangle (region). Rectus capitis posterior minor 3 Muscles Trapezius Superior nuchal line External occipital protuberance Inferior nuchal line Rectus capitis posterior major Semispinalis capitis Sternocleidomastoid Obliquus capitis superior Splenius capitis Obliquus capitis superior Mastoid process Longissimus capitis Posterior atlanto-occipital membrane (pierced by vertebral a.) Transverse process of atlas (C1) Rectus capitis posterior major Posterior arch of atlas (C1) Obliquus capitis inferior Spinous process of axis (C2) Interspinales cervicis Intertransversarii cervicis Transverse process of C7 Spinous process of C7 A Course of the short nuchal muscles. Semispinalis capitis Rectus capitis posterior minor Rectus capitis posterior major Trapezius Sternocleidomastoid Splenius capitis Obliquus capitis superior Longissimus capitis Obliquus capitis inferior Intertransversarii cervicis Interspinales cervicis B Suboccipital region. Muscle origins are shown in red, insertions in blue. 27 Back Intrinsic Muscles of the Back The extrinsic muscles of the back (trapezius, latissimus dorsi, levator scapulae, and rhomboids) are discussed in the Upper Limb, pp. 312–313. The serratus posterior, considered an intermediate extrinsic back muscle, has been included with the superficial intrinsic muscles in this unit. Fig. 3.5 Intrinsic muscles of the back Posterior view. Sequential dissection of the thoracolumbar fascia, superficial intrinsic muscles, intermediate intrinsic muscles, and deep intrinsic muscles of the back. Thoracolumbar fascia (= deep layer of nuchal fascia) Rhomboids major and minor (cut) Serratus posterior superior Semispinalis capitis Splenius capitis External intercostal muscles Trapezius (cut) Thoracolumbar fascia, posterior layer Splenius cervicis Thoracolumbar fascia (= deep layer of nuchal fascia) Serratus posterior inferior Internal oblique Latissimus dorsi (cut) aponeurosis External oblique (cut) External oblique Iliac crest External intercostal muscles Spinalis Iliocostalis Longissimus External oblique Gluteus maximus Internal oblique Iliac crest A Thoracolumbar fascia. Removed: Shoulder girdles and extrinsic back muscles (except serratus posterior and aponeurotic origin of latissimus dorsi). Revealed: Posterior layer of thoracolumbar fascia. Thoracolumbar fascia, posterior layer B Superficial and intermediate intrinsic back muscles. Removed: Thoracolumbar fascia, posterior layer (left). Revealed: Erector spinae and splenius muscles. 28 Splenius capitis (cut) Longissimus capitis Splenius capitis Iliocostalis cervicis Splenius cervicis Iliocostalis thoracis 3 Muscles Semispinalis capitis External intercostal muscles Levatores costarum Spinalis Longissimus thoracis Semispinalis capitis Superior nuchal line Splenius capitis Rectus capitis posterior minor Obliquus capitis superior Iliocostalis lumborum Internal oblique Transversus abdominis Obliquus capitis inferior Rectus capitis posterior major Longissimus capitis Interspinales cervicis Spinalis cervicis Iliac crest Rotatores thoracis longi Levatores costarum longi Gluteus maximus Multifidus Thoracolumbar fascia, posterior layer C Intermediate and deep intrinsic back muscles. Removed: Longissimus thoracis and cervicis, splenius muscles (left); iliocostalis (right). Note: The posterior layer of the thoracolumbar fascia gives origin to the internal oblique and transversus abdominis. Revealed: Deep muscles of the back. Rotatores thoracis breves External intercostal muscles Spinalis thoracis Levatores costarum breves Medial intertransversarii lumbora 12th rib Interspinales lumborum Lateral intertransversarii lumbora Transversus abdominis Costal processes Iliac crest Thoracolumbar fascia, posterior layer Multifidus Quadratus lumborum DDeep intrinsic back muscles. Removed: Superficial and intermediate intrinsic back muscles (all); deep fascial layer and multifidus (right). Revealed: Intertransversarii and quadratus lumborum (right). 29 Back Muscle Facts (I) Fig. 3.6 Short nuchal and craniovertebral joint muscles Superior nuchal line Inferior nuchal line Rectus capitis posterior minor Obliquus capitis superior Mastoid process ② ① Rectus capitis posterior major Posterior tubercle of atlas (C1) ③ Transverse process of atlas (C1) Spinous process of axis (C2) Obliquus capitis inferior ④ A Posterior view, schematic. B Suboccipital muscles, posterior view. Mastoid process Transverse process of atlas (C1) External occipital protuberance Mandible Obliquus capitis superior Atlas (C1) Rectus capitis posterior minor Axis (C2) Rectus capitis posterior major Obliquus capitis inferior Spinous process of axis (C2) C Suboccipital muscles, left lateral view. Table 3.1 Short nuchal and craniovertebral joint muscles Muscle Rectus capitis posterior Origin Insertion ① Rectus capitis C2 (spinous process) Occipital bone (inferior nuchal line, middle third) ② Rectus capitis C1 (posterior tubercle) Occipital bone (inferior nuchal line, inner third) posterior major posterior minor ③ Obliquus capitis C1 (transverse Obliquus capitis superior ④ Obliquus capitis C2 (spinous inferior 30 process) process) Occipital bone (inferior nuchal line, middle third; above rectus capitis posterior major) C1 (transverse process) Innervation C1 (posterior ramus = suboccipital n.) Action Bilateral: Extends head Unilateral: Rotates head to same side Bilateral: Extends head Unilateral: Flexes head to same side; rotates to opposite side Bilateral: Extends head Unilateral: Rotates head to same side Occipital bone, basilar portion 3 Muscles Fig. 3.7 Prevertebral muscles Rectus capitis anterior Occipital bone, basilar portion ① Atlas (C1) ③ ④ Axis (C2) Rectus capitis lateralis Mastoid process ② Transverse process of atlas (C1) Longus capitis C7 vertebra T3 vertebra Axis (C2) A Anterior view, schematic. Superior oblique part Anterior tubercle Vertical part Longus colli Inferior oblique part C7 vertebra 1st rib T3 vertebra Prevertebral muscles, anterior view. B Removed: Longus capitis (left); cervical viscera. Table 3.2 Prevertebral muscles Muscle Origin Insertion Innervation Action ① Longus capitis C3–C6 (transverse processes, anterior tubercles) Occipital bone (basilar part) Direct branches from cervical plexus (C1–C3) Bilateral: Flexes head Unilateral: Flexes and slightly rotates head to same side C5–T3 (anterior sides of vertebral bodies) C2–C4 (anterior sides of vertebral bodies) part C3–C5 (transverse processes, anterior tubercles) C1 (transverse process, anterior tubercle) Inferior oblique part T1–T3 (anterior sides of vertebral bodies) C5–C6 (transverse processes, anterior tubercles) Direct branches from cervical plexus (C2–C6) Bilateral: Flexes cervical spine Unilateral: Flexes and rotates cervical spine to same side C1 (lateral mass) Occipital bone (basilar part) C1 (transverse process) Occipital bone (basilar part, lateral to occipital condyles) C1 (anterior ramus) Bilateral: Flexion at atlanto-occipital joint Unilateral: Lateral flexion at atlantooccipital joint Vertical (medial) part ② Longus colli Superior oblique (cervicis) ③ Rectus capitis anterior ④ Rectus capitis lateralis 31 Back Muscle Facts (II) The intrinsic back muscles are divided into superficial, intermediate, and deep layers. The serratus posterior muscles are extrinsic back muscles, innervated by the anterior rami of intercostal nerves, not Superficial intrinsic back muscles Table 3.3 Muscle Serratus posterior Splenius the posterior rami, which innervate the intrinsic back muscles. They are included here as they are encountered in dissection of the back musculature. Origin Insertion Innervation Action ① erratus posterior S superior Nuchal lig.; C7–T3 (spinous processes) 2nd–4th ribs (superior borders) Spinal nn. T2–T5 (anterior rami) Elevates ribs ② erratus posterior S inferior T11–L2 (spinous processes) 8th–12th ribs (inferior borders, near angles) Spinal nn. T9–T12 (anterior rami) Depresses ribs ③ S plenius capitis Nuchal lig.; C7–T3 or T4 (spinous processes) Lateral 1/3 nuchal line (occipital bone); mastoid process (temporal bone) ④ S plenius cervicis T3–T6 or T7 (spinous processes) C1–C3/4 (transverse processes) Spinal nn. C1–C6 (posterior rami, lateral branches) Bilateral: Extends cervical spine and head Unilateral: Laterally flexes and rotates head to the same side Fig. 3.8 Superficial intrinsic back muscles, schematic Fig. 3.9 Intermediate intrinsic back muscles, schematic Right side, posterior view. These muscles are collectively known as the erector spinae. Right side, posterior view. ③ ⑧ ⑤ ④ ① ⑨ ⑪ ⑥ ⑩ ② A Serratus posterior. Table 3.4 32 A Iliocostalis muscles. B Longissimus muscles. C Spinalis muscles. Intermediate intrinsic back muscles (erector spinae) Origin Insertion ⑤ Iliocostalis cervicis 3rd–7th ribs C4–C6 (transverse processes) ⑥ Iliocostalis thoracis 7th–12th ribs 1st–6th ribs ⑦ Iliocostalis lumborum Sacrum; iliac crest; thoracolumbar fascia (posterior layer) 6th–12th ribs; thoracolumbar fascia (posterior layer); upper lumbar vertebrae (transverse processes) ⑧ Longissimus capitis T1–T3 (transverse processes); C4–C7 (transverse and articular processes) Temporal bone (mastoid process) ⑨ Longissimus cervicis T1–T6 (transverse processes) C2–C5 (transverse processes) ⑩ Longissimus thoracis Sacrum; iliac crest; lumbar vertebrae (spinous processes); lower thoracic vertebrae (transverse processes) 2nd–12th ribs; thoracic and lumbar vertebrae (transverse processes) ⑪ Spinalis cervicis C5–T2 (spinous processes) C2–C5 (spinous processes) Iliocostalis Spinalis ⑦ B Splenius muscles. Muscle Longissimus ⑫ ⑫ Spinalis thoracis T10–L3 (spinous processes, lateral surfaces) T2–T8 (spinous processes, lateral surfaces) Innervation Action Spinal nn. C8–L1 (posterior rami, lateral branches) Bilateral: Extends spine Unilateral: Flexes spine laterally to same side Bilateral: Extends head Unilateral: Flexes and rotates head to same side Spinal nn. C1–L5 (posterior rami, lateral branches) Spinal nn. (posterior rami) Bilateral: Extends spine Unilateral: Flexes spine laterally to same side Bilateral: Extends cervical and thoracic spine Unilateral: Flexes cervical and thoracic spine to same side Fig. 3.10 Superficial and intermediate intrinsic back muscles Posterior view. 3 Muscles Superior nuchal line Mastoid process Splenius capitis Spinous process of C7 Splenius cervicis Serratus posterior superior 4th rib Longissimus capitis 8th rib Spinalis cervicis Serratus posterior inferior Iliocostalis cervicis Longissimus cervicis 12th rib L2 Iliocostalis thoracis Spinalis thoracis Longissimus thoracis A Superficial back muscles: Splenius and serratus posterior muscles. Iliocostalis lumborum B Intermediate intrinsic back muscles (erector spinae): Iliocostalis, longissimus, and spinalis muscles. 33 Back Muscle Facts (III) The deep intrinsic back muscles are divided into two groups: trans­ versospinalis and deep segmental muscles. The transversospinalis Table 3.5 muscles pass between the transverse and spinous processes of the vertebrae. Transversospinalis muscles Muscle Origin Insertion Innervation ① Rotatores breves T1–T12 (between transverse and spinous processes of adjacent vertebrae) ② Rotatores longi T1–T12 (between transverse and spinous processes, skipping one vertebra) Rotatores Sacrum, ilium, mamillary processes of L1–L5, transverse and articular processes of T1–T4, C4–C7 Superomedially to spinous processes, skipping two to four vertebrae ④ Semispinalis capitis C4–T7 (transverse and articular processes) Occipital bone (between superior and inferior nuchal lines) ⑤ Semispinalis cervicis T1–T6 (transverse processes) C2–C5 (spinous processes) ⑥ Semispinalis thoracis T6–T12 (transverse processes) C6–T4 (spinous processes) Multifidus ③ Semispinalis Action Bilateral: Extends thoracic spine Unilateral: Rotates thoracic spine to opposite side Spinal nn. (posterior rami) Fig. 3.11 Transversospinalis muscles Bilateral: Extends spine Unilateral: Flexes spine to same side, rotates it to opposite side Bilateral: Extends thoracic and cervical spines and head (stabilizes craniovertebral joints) Unilateral: Flexes head, cervical and thoracic spines to same side, rotates to opposite side Fig. 3.12 Deep segmental muscles Posterior view, schematic. Posterior view, schematic. ④ ⑦ ⑤ ⑫ A ③ ② ⑥ ⑬ ⑧ Rotatores A muscles. Table 3.6 B Multifidus. Intertransversarii* Levatores costarum ⑪ C Semispinalis. Origin Insertion ⑦ Interspinales cervicis C1–C7 (between spinous processes of adjacent vertebrae) ⑧ Interspinales lumbora L1–L5 (between spinous processes of adjacent vertebrae) Anterior intertransversarii cervices C2–C7 (between anterior tubercles of adjacent vertebrae) ⑨P osterior intertransversarii cervices C2–C7 (between posterior tubercles of adjacent vertebrae) ⑩ Medial intertransversarii lumbora L1–L5 (between mammillary processes of adjacent vertebrae) ⑪ Lateral intertransversarii lumbora L1–L5 (between transverse processes of adjacent vertebrae) ⑫ Levatores costarum breves ⑬ Levatores costarum longi Costal angle of next lower rib C7–T11 (transverse processes) Costal angle of rib two vertebrae below Innervation Action Spinal nn. (posterior rami) Extends cervical and lumbar spines Spinal nn. (anterior rami) Spinal nn. (posterior rami) Bilateral: Stabilizes and extends the cervical and lumbar spines Unilateral: Flexes the cervical and lumbar spines laterally to same side Spinal nn. (anterior rami) Spinal nn. (posterior rami) Bilateral: Extends thoracic spine Unilateral: Flexes thoracic spine to same side, rotates to opposite side *Both the interspinales and intertransversarii muscles traverse the entire spine; only their clinically relevant components have been included. 34 ⑩ Deep segmental back muscles Muscle Interspinales* ⑨ Fig. 3.13 Deep intrinsic back muscles Superior nuchal line 3 Muscles Inferior nuchal line Posterior view. Semispinalis capitis Semispinalis cervicis Spinous process of C7 Semispinalis thoracis Transverse process Spinous process Rotatores longi Interspinales cervicis Posterior intertransversarii cervices Rotatores breves Transverse processes Levatores costarum longi Multifidus Levatores costarum breves Sacrum Medial intertransversarii lumbora A Transversospinalis muscles: Rotatores, multifidus, and semispinalis. Interspinales lumbora Lateral intertransversarii lumbora B Deep segmental muscles: Interspinales, intertransversarii, and levatores costarum. 35 4 Neurovasculature Back Arteries & Veins of the Back Internal carotid a. Fig. 4.1 Arteries of the back External carotid a. The structures of the back are supplied by branches of the posterior intercostal arteries, which arise from the thoracic aorta or from the subclavian artery. Right common carotid a. Right subclavian a. Vertebral a. Brachiocephalic trunk Right common carotid a. Aortic arch Posterior intercostal aa. Anterior intercostal aa. Thoracic aorta Right subclavian a. 1st posterior intercostal a. Internal thoracic a. 2nd posterior intercostal a. Abdominal aorta A Arteries of the trunk, right lateral view. Thyrocervical trunk Costocervical trunk Subcostal a. B Vascular supply to the nuchal region, posterolateral view. Note: The first and second posterior intercostal arteries arise from the costocervical trunk, a branch of the subclavian artery. External iliac a. Sternal brs. Lateral cutaneous br. Dorsal branch of posterior intercostal a. Anterior cutaneous br. Spinal br. Internal thoracic a. Posterior intercostal a. Medial cutaneous br. Anterior intercostal a. Thoracic aorta Posterior intercostal a. Abdominal aorta Median sacral a. Lateral cutaneous br. C Posterior intercostal arteries, oblique posterosuperior view. The posterior intercostal arteries give rise to cutaneous and muscular branches, as well as spinal branches that supply the spinal cord. Common iliac a. External iliac a. Internal iliac a. Lateral sacral a. Coccyx DVascular supply to the sacrum, anterior view. 36 Fig. 4.2 Veins of the back 4 Neurovasculature The veins of the back drain into the azygos vein via the posterior intercostal veins, hemiazygos vein, and ascending lumbar veins. The interior of the spinal column is drained by the vertebral venous plexus that runs the length of the spine. Right internal jugular v. Right subclavian v. Right brachiocephalic v. Azygos v. Superior vena cava Superior sagittal sinus Transverse sinus Posterior intercostal vv. Sigmoid sinus Anterior intercostal vv. Inferior vena cava Subcostal v. Emissary v. External vertebral venous plexus Internal jugular v. Left brachiocephalic v. Right brachiocephalic v. Superior vena cava Accessory hemiazygos v. External iliac v. A Veins of the trunk, right lateral view. Azygos v. Posterior intercostal vv. Hemiazygos v. External vertebral venous plexus Lateral cutaneous br. Posterior internal vertebral venous plexus Medial cutaneous br. Lumbar v. Ascending lumbar v. Posterior intercostal v. Posterior internal vertebral venous plexus Anterior internal vertebral venous plexus Anterior internal vertebral venous plexus Azygos v. Anterior external vertebral venous plexus Intervertebral v. Hemiazygos v. C Intercostal veins and anterior vertebral venous plexus, anterosuperior view. The intercostal veins follow a similar course to the intercostal nerves and arteries (see pp. 36, 38). Note: The anterior external vertebral venous plexus can be seen communicating with the azygos vein. External iliac v. Internal iliac v. B Vertebral venous plexus, posterior view with vertebral canal windowed in the lumbar and sacral spine. The external vertebral venous plexus communicates with the sigmoid sinus through emissary veins in the skull. The external vertebral venous plexus is divided into an anterior and a posterior portion that run along the exterior of the vertebral column. The anterior and posterior internal vertebral venous plexus run in the vertebral foramen and drain the spinal cord. 37 Back Nerves of the Back The back receives its innervation from branches of the spinal nerves. The posterior (dorsal) rami of the spinal nerves supply most of the intrinsic muscles of the back. The extrinsic muscles of the back are supplied by the anterior (ventral) rami of the spinal nerves. Fig. 4.3 Nerves of the back Cross section of the vertebral column and spinal cord with surrounding musculature, superior view. Esophagus Aorta Sympathetic (paravertebral) ganglion Outer layer, dura mater White and gray rami communicans Anterior root Meningeal br. Inner layer, arachnoid mater Spinal ganglion Posterior root Spinal n. Medial cutaneous br. Lateral cutaneous br. 38 Anterior (ventral) ramus Posterior (dorsal) ramus Fig. 4.4 Nerves of the nuchal region Right side, posterior view. Nerves of the nuchal region Posterior (dorsal) ramus Anterior (ventral) ramus Function Suboccipital n. (C1) Innervates the rectus capitis posterior major and minor; and obliquus capitis superior and inferior Greater occipital n. (C2) Assits in the innervation of the semispinalis capitis muscle and supplies skin behind the auricle and the scalp to the coronal suture Third occipital n. (C3) Assists in the innervation of the semispinalis capitis muscle, the C2-C3 facet joint, and supplies a small area of skin just below the superior nuchal line Lesser occipital n. (C2) Cutaneous only, supplies an area of scalp posterolateral to the auricle, and the skin on the upper third of the medial aspect of the auricle 3rd occipital n. (C3) Greater auricular n. (C2, C3) Cutaneous only, supplies an area of skin over the parotid gland, the majority of the pinna, lateral neck, and posterior to the auricle Supraclavicular nn. Lesser occipital n. 4 Neurovasculature Table 4.1 Branches Suboccipital n. (C1) Great auricular n. Greater occipital n. (C2) **The anterior rami of C1-C3 also give rise to the ansa cervicalis, which innervates the infrahyoid muscles (see p. 524). C5 spinal n., posterior ramus Fig. 4.5 Cutaneous innervation of the back Color denotes the skin areas innervated by (A) particular peripheral nerves or (B) particular pairs of segmental spinal nerves. Patterns of loss of cutaneous sensation can be helpful in diagnosis of nerve lesions. Greater occipital n. C2 Lesser occipital n. C3 C5 C8 T1 Great auricular n. C4 Supraclavicular nn. C5 Medial cutaneous brs. Axillary n. Spinal nn., (posterior rami) C6 Lateral cutaneous brs. T1 Intercostal nn., (anterior rami, lateral cutaneous brs.) L1 Superior clunial nn. Middle clunial nn. Iliohypogastric n. A Cutaneous innervation patterns of specific peripheral nerves. Dermatomes: Dermatomes are bilateral band-like areas of skin reB ceiving innervation from a single pair of spinal nerves (from a single segment of the spinal cord). Note: Spinal nerve C1 is purely motor; consequently there is no C1 dermatome. 39 Back Spinal Cord terminates at the foramen magnum and is replaced in the vertebral canal with the periosteum of the vertebral bone. Due to this structural difference in the two regions, the dural sac is not adherent to the bone of the vertebral canal as it is in the cranial cavity. The dura mater of the cranial cavity is composed of two layers, the periosteal and meningeal. Only the meningeal layer extends into the vertebral canal with the spinal cord. The periosteal layer of dura Fig. 4.6 Spinal cord in situ Posterior view with vertebral canal windowed. C1 spinal n. Atlas (C1) Vertebra prominens (C7) T1 spinal n. Medulla oblongata Cervical enlargement Fig. 4.7 Spinal cord and its meningeal layers Posterior view. The dura mater is opened and the arachnoid is sectioned. The detailed anatomy of the spinal cord can be found on pp. 690–691. Spinal cord Anterior spinal a. Anterior spinal vv. Pia mater Subarachnoid space Posterior root Spinal ganglion Arachnoid (mater) Subdural space Dura mater Posterior ramus Anterior ramus Anterior root Spinal n. White and gray rami communicans Denticulate lig. Anterior rootlets T12 vertebra L1 spinal n. Lumbosacral enlargement Conus medullaris Cauda equina L5 vertebra S1 spinal n. Dura mater Arachnoid (mater) Fig. 4.8 Cervical spinal cord in situ: Transverse section Epidural space Superior view. Spinal cord at level of C4 ­vertebra. Posterior internal vertebral venous plexus Subarachnoid space Arachnoid (mater) Dura mater Denticulate lig. Intervertebral foramen Posterior root Anterior root Spinal ganglion Spinal n. Vertebral a. Vertebral vv. Sacral hiatus Anterior internal vertebral venous plexus Root sleeve Clinical box 4.1 Spina Bifida Spina bifida is a neural tube defect that occurs when the spine and spinal cord do not form properly. In the United States, it affects about one out of every 1,500 newborns. There are three main types. • Spina bifida occulta (A) is the most common congenital anomaly of the vertebral column in which the laminae of L5 and/or S1 fail to develop. The defect is often hidden and most individuals are unaware they have the condition because there is only a small defect in the vertebrae. There is generally no disturbance of spinal function. • Spina bifida (meningocele) (B) occurs when one or more vertebral arches fail to develop and presents with a herniation or sac of only the meninges. The spinal cord and nerves are normal and not severely affected. 40 • Spina bifida (myelomeningocele) (C) occurs when multiple vertebral arches fail to develop resulting in a herniation of both the meninges and spinal nerves. This is the most severe form exposing the newborn to life threatening infections, bowel and bladder dysfunction, and total paralysis of the lower extremities. A B C Fig. 4.9 Cauda equina in the vertebral canal Fig. 4.10 Cauda equina in situ: Transverse section Posterior view. The lamina and posterior surface of the sacrum have been partially removed. Superior view. Cauda equina at level of L2 vertebra. Fatty tissue Epidural space Conus medullaris Cauda equina Spinal ganglion Dural sac Spinal ganglion Spinal dura mater Cauda equina (posterior and anterior spinal roots) 4 Neurovasculature Posterior internal vertebral venous plexus L1 vertebra Anterior internal vertebral venous plexus Dura mater Arachnoid (mater) Clinical box 4.2 Sacral hiatus Fig. 4.11 Spinal cord, dural sac, and vertebral column at different ages. Anterior view. Longitudinal growth of the spinal cord lags behind that of the vertebral column. At birth, the distal end of the spinal cord, the conus medullaris, is at the level of the L3 vertebral body, but in the average adult it extends to the level of L1/L2. The dural sac always extends into the upper sacrum. Lumbar puncture Filum terminale Conus medullaris (adult) A needle introduced into the dural sac (lumbar cistern) generally slips past the spinal nerve roots without injuring the spinal cord or spinal nerves. Cerebrospinal fluid (CSF) samples are therefore taken between the L3 and L4 vertebrae (2), once the patient has leaned forward to separate the spinous processes of the lumbar spine. T 12 Conus medullaris Cauda equina L1 1 2 Conus medullaris (newborn) Dural sac (lumbar cistern) Sacral hiatus 3 Anesthesia Lumbar anesthesia may be administered in a similar fashion (2). Epidural anesthesia is administered by placing a catheter in the epidural space without penetrating the dural sac (1). This may also be done by passing a needle through the sacral hiatus (3). 41 Back Spinal Cord Segments & Spinal Nerves Fig. 4.12 Spinal cord segment The spinal cord consists of 31 segments, each innervating a specific area of the skin (a dermatome) of the head, trunk, or limbs. Afferent (sensory) posterior rootlets and efferent (motor) anterior rootlets form the posterior and anterior roots of the spinal nerve for that segment. The two roots fuse to form a mixed (motor and sensory) spinal nerve that exits the intervertebral foramen and immediately thereafter divides into an anterior and posterior ramus. Posterior rootlets Gray matter, posterior horn Posterior root (with spinal ganglion) Spinal n. White matter Posterior ramus Gray matter, anterior horn Anterior ramus Fig. 4.13 Spinal cord segments, dermatomes, and effects of spinal cord lesions Anterior root The spinal cord is divided into four major regions: cervical, thoracic, lumbar, and sacral. The regions of the spinal cord are designated by colors: red, cervical; brown, thoracic; green, lumbar; blue, sacral. Spinal cord segment C1 Meningeal br. Anterior rootlets Splanchnic nn. Vertebra Atlas (C1) Axis (C2) Gray ramus communicans White ramus communicans Sympathetic (paravertebral) ganglion Sympathetic trunk T2 C8 T1 S1 L5 L1 C2 T1 C7 T1 C3 Cervical cord lesion C4 C5 T12 L1 S1 C6 S5 T1 T12 Thoracic cord lesion L1 C7 L5 C8 Lumbar cord lesion S1 Coccyx A Spinal cord segments. Initially spinal nerves pass out above the vertebrae for which they are numbered. However, since there is an 8th cervical spinal nerve but no 8th cervical vertebrae, C8 passes out above vertebral level T1, and the spinal nerve for T1, and those following, pass out below the vertebral level for which they are numbered. 42 Conus/cauda equina lesion B Dermatomes, band-like areas of skin receiving sensory innervation from a single pair of spinal nerves (from a single segment of the spinal cord). Note: Spinal nerve C1 is purely motor; consequently there is no C1 dermatome. C Effects of lesions in each region of the spinal cord. Fig. 4.14 Spinal nerve branches 4 Neurovasculature Anterior cutaneous br. Posterior ramus Spinal cord Articular br. Spinal ganglion White and gray rami communicans* Sympathetic ganglion Sympathetic trunk Lateral cutaneous br. Meningeal br. Anterior ramus Lateral br. Medial br. Anterior sacral foramen Anterior root A Superolateral view of a thoracic spinal nerve. The posterior (dorsal) rami of the spinal nerves give rise to muscular and cutaneous branches, as well as articular branches to the zygapophyseal joints. The anterior (ventral) rami of the spinal nerves form the cervical plexus (C1–C4), the brachial plexus (C5–T1), the lumbar plexus (T12–L4), and the sacral plexus (L4–S3). The anterior rami of spinal nerves T1–T11 produce the intercostal nerves (T12 produces the subcostal nerve). Anterior ramus (to sacral plexus) Spinal ganglion Posterior ramus Cauda equina Posterior root Posterior sacral foramen Lateral br. (to the clunial nerves) B Spinal nerve branches in the sacral foramina. Superior view of transverse section through right half of sacrum. Table 4.2 Branches of a spinal nerve Branches Territory Meningeal br. Posterior (dorsal) ramus Spinal meninges; ligaments of spinal column Medial brs. Zygapophyseal joints Muscular br. Intrinsic back muscles Cutaneous br. Lateral brs. Anterior (ventral) ramus Articular br. Cutaneous br. Muscular br. Skin of posterior head, neck, back, and buttocks Intrinsic back muscles Lateral cutaneous brs. Skin of lateral chest wall Anterior cutaneous brs. Skin of anterior chest wall *The white and gray rami communicans carry pre- and postganglionic fibers between the sympathetic trunk and spinal n. 43 Back Arteries & Veins of the Spinal Cord Like the spinal cord itself, the arteries and veins of the spinal cord consist of multiple horizontal systems (blood vessels of the spinal cord segments) that are integrated into a vertical system. Fig. 4.15 Arteries of the spinal cord Basilar a. The unpaired anterior and paired posterior spinal arteries typically arise from the vertebral arteries. As they descend within the vertebral canal, the spinal arteries are reinforced by anterior and posterior segmental medullary arteries. Depending on the spinal level, these reinforcing branches may arise from the vertebral, ascending or deep cervical, posterior intercostal, lumbar, or lateral sacral arteries. Vertebral a. Anterior spinal a. Posterior spinal a. Posterior spinal aa. Vertebral a. Anterior segmental medullary a. Ascending cervical a. Posterior segmental medullary a. Posterior horn Anterior horn Spinal br. Subclavian a. Sulcal a. Anterior spinal a. Segmental a. Vasocorona Posterior intercostal aa. Posterior segmental medullary a. Anterior segmental medullary a. A Spinal and segmental medullary arteries. Posterior segmental medullary a. Medial cutaneous br. Posterior segmental medullary a. Lateral cutaneous br. Posterior intercostal a. Spinal br. Anterior segmental medullary a. Posterior intercostal a. B Origins of the segmental medullary arteries. In the thorax, the segmental medullary arteries arise from the spinal branch of the posterior intercostal arteries (see p. 36). 44 Lumbar aa. Posterior (dorsal) br. Thoracic aorta C Arterial supply system. Great anterior segmental medullary a. Fig. 4.16 Veins of the spinal cord Posterior spinal v. Sulcal v. Venous ring Posterior radicular v. 4 Neurovasculature The interior of the spinal cord drains via venous plexuses into an anterior and a posterior spinal vein. The radicular and spinal veins connect the veins of the spinal cord with the internal vertebral venous plexus. The intervertebral and basivertebral veins connect the internal and external venous plexuses, which drain into the azygos system. Spinal v. Right deep cervical v. Anterior spinal v. Anterior spinal v. B Spinal and radicular veins. Posterior internal vertebral venous plexus Right vertebral v. Right subclavian v. Right internal jugular v. Superior vena cava Left brachiocephalic v. Basivertebral v. Anterior radicular v. Anterior external vertebral venous plexus C Vertebral venous plexuses. Anterior spinal v. Ascending lumbar v. Intervertebral v. Hemiazygos v. Posterior internal vertebral venous plexus (in epidural space) Basivertebral v. Inferior vena cava Common iliac v. Venous drainage A system. Intervertebral v. Subcostal v. Posterior radicular v. Ascending lumbar v. Anterior internal vertebral venous plexus Accessory hemiazygos v. Intercostal vv. Azygos v. Anterior radicular v. Ascending lumbar v. Medial and lateral epidural vv. Internal iliac v. DVeins in the sacral and lumbar canals. Anterior internal vertebral venous plexus External iliac v. 45 Back Neurovascular Topography of the Back Fig. 4.17 Neurovasculature of the nuchal region Posterior view. Removed: Trapezius, sternocleidomastoid, and semispinalis capitis. Revealed: Suboccipital region. Obliquus capitis superior Rectus capitis posterior minor Occipital a. Greater occipital n. Vertebral a. Rectus capitis posterior major Suboccipital n. 3rd occipital n. Atlas (C1), transverse process Obliquus capitis inferior Lesser occipital n. Axis (C2), spinous process Great auricular n. Sternocleidomastoid Deep cervical a. Longissimus capitis Semispinalis cervicis 46 Semispinalis capitis Fig. 4.18 Neurovasculature of the back 4 Neurovasculature Posterior view. Removed: Muscle fascia (except posterior layer of thoracolumbar fascia); latissimus dorsi (right). Reflected: Trapezius (right). Revealed: Transverse cervical artery in the deep scapular region. See p. 72 for the course of the intercostal vessels. Dorsal scapular n. 3rd occipital n. Transverse cervical a. Splenius capitis Accessory n. Rhomboid major Trapezius Spinal nn., posterior rami (lateral cutaneous brs.) Deltoid Thoracolumbar fascia, posterior layer Serratus posterior inferior Intercostal nn. and posterior intercostal aa. and vv. (lateral cutaneous brs.) Latissimus dorsi Fibrous lumbar triangle (of Grynfeltt) External oblique Iliolumbar triangle (of Petit) Internal oblique Iliac crest Superior clunial nn. Middle clunial nn. Inferior clunial nn. 47 5 Sectional & Radiographic Anatomy Back Radiographic Anatomy of the Back (I) Nuchal lig. Cervical vertebrae C1-C7 Dens of axis (C2) Fig. 5.1 MRI of the spine Sagittal view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Vertebra prominens (C7) Body of thoracic vertebra T1 Vertebral canal Spinal cord (thoracic part) Thoracic vertebrae T1-T12 Intervertebral disk Supraspinous lig. Interspinous ligs. Body of lumbar vertebra L1 Conus medullaris Lumbar vertebrae L1-L5 Cauda equina Spinous process Dural sac Sacrum (sacral vertebrae) S1-S5 Coccyx (coccygeal vertebrae) Co1-Co3 or Co4 Sacrum (S1) Sacral promontory Coccyx Thoracic vertebral body T12 Fig. 5.2 MRI of the lumbar spine Parasagittal view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Mammillary process Erector spinae Lumbar vertebral body L2 Inferior vena cava Spinal ganglion L2 Lamina Intervertebral disk L3/L4 (nucleus pulposus) Superior articular process Common iliac a. Intervertebral foramen Inferior articular process Zygapophyseal joint Multifidus Promontory of sacrum Sacrum (S1) 48 Gluteus maximus Fig. 5.3 Radiograph of the cervical spine Lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Odontoid process Mandible Body of the axis Anterior superior margin of the vertebra Anterior inferior margin of the vertebra Base of the skull Posterior arch of the atlas Spinous process Transverse process 5 Sectional & Radiographic Anatomy Anterior arch of the atlas Superior articular facet Superior vertebral end plate Inferior vertebral end plate Inferior articular facet Intervertebral facet joint Intervertebral disk space Articular pillar Lamina Spinous process Trachea Fig. 5.4 Radiograph of the thoracic spine Anteroposterior view. Lower thoracic region. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Transverse process Body of vertebra Pedicle Spinous process Intervertebral disk 49 Back Radiographic Anatomy of the Back (II) Fig. 5.5 Radiograph of the lumbar spine Lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Inferior vertebral end plate Superior vertebral end plate Pedicle Intervertebral foramen Facet joint Invertebral disk space Inferior articular process Superior articular process Promontory of sacrum Fig. 5.6 Radiograph of the lumbar spine Oblique view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Body of vertebra Body of vertebra Intervertebral disk space Ribs Ipsilateral transverse process Pedicle Interarticular part Lamina Contralateral transverse process Superior articular process Intervertebral foramen Intervertebral disk space Ribs Ipsilateral transverse process Pedicle Inferior articular process Spinous process A 50 B Interarticular part Lamina Contralateral transverse process Superior articular process Intravertebral foramen Inferior articular process Spinous process Fig. 5.7 MRI of the sacrum I Oblique view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Ileum Internal oblique Iliac aa. Transversus abdominis Psoas major Iliacus 5th lumbar nerve root Anterior sacroiliac ligs. Gluteus medius Gluteus maximus Anterior sacral foramina Common iliac a. and v. Descending colon Ilium (wing) L5 vertebra, body Sacroiliac joint Sacrum (lateral mass) Interosseous sacroiliac ligs. 5 Sectional & Radiographic Anatomy External oblique Posterior sacroiliac ligs. Sacral canal Fig. 5.8 MRI of the sacrum II Oblique view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Ascending colon L5 vertebra, body Sacrum (S1, body) Descending colon Psoas major Iliacus Dural sac Ilium, wing Posterior sacroiliac ligs. Gluteus maximus Spinal n. roots in sacral spinal canal 51 Thorax 6 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 7 Thoracic Wall Thoracic Skeleton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sternum & Ribs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Thoracic Cage . . . . . . . . . . . . . . . . . . . . . . . . . . . Thoracic Wall Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Diaphragm . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Thoracic Wall . . . . . . . . . . . . . . . . . . . . Nerves of the Thoracic Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovascular Topography of the Thoracic Wall . . . . . . . . . . . Female Breast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Female Breast . . . . . . . . . . . . . . . . . . . . . . . 56 58 60 62 64 66 68 70 72 74 76 8 Thoracic Cavity Divisions of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . Arteries of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . Veins of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . Nerves of the Thoracic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . 78 80 82 84 86 9 Mediastinum Mediastinum: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Mediastinum: Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Heart: Functions & Relations . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Pericardium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Heart: Surfaces & Chambers . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Heart: Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Arteries & Veins of the Heart . . . . . . . . . . . . . . . . . . . . . . . . . 100 Conduction & Innervation of the Heart . . . . . . . . . . . . . . . . . 102 Pre- & Postnatal Circulation . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Esophagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Neurovasculature of the Esophagus . . . . . . . . . . . . . . . . . . . 108 Lymphatics of the Mediastinum . . . . . . . . . . . . . . . . . . . . . . . 110 10 Pulmonary Cavities Pulmonary Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pleura: Subdivisions, Recesses & Innervation . . . . . . . . . . . . Lungs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bronchopulmonary Segments of the Lungs . . . . . . . . . . . . . Trachea & Bronchial Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . Respiratory Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pulmonary Arteries & Veins . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Tracheobronchial Tree . . . . . . . . . . Lymphatics of the Pleural Cavity . . . . . . . . . . . . . . . . . . . . . . 112 114 116 118 120 122 124 126 128 11 Sectional & Radiographic Anatomy Sectional Anatomy of the Thorax . . . . . . . . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (I). . . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (II). . . . . . . . . . . . . . . . Radiographic Anatomy of the Thorax (III). . . . . . . . . . . . . . . . 130 132 134 136 6 Surface Anatomy Thorax Surface Anatomy Fig. 6.1 Regions of the thorax Presternal region Anterior view. Infraclavicular fossa Clavipectoral triangle Deltoid region Axillary region Pectoral region Inframammary region Lateral pectoral region Epigastric region (epigastrium) Hypochondriac region Midclavicular line (MCL) Fig. 6.2 Palpable structures of the thorax Anterior view. Coracoid process Supraclavicular fossa Clavicle, medial head Greater and lesser tubercles Sternal angle Xiphoid process A Bony prominences. Subcostal plane Sternocleidomastoid Supraclavicular fossa Deltoid Deltopectoral groove Pectoralis major Serratus anterior B Musculature. 54 Thyroid cartilage Jugular notch Fig. 6.3 Vertical reference lines of the thorax 6 Surface Anatomy Anterior axillary line Anterior midline Sternal line Parasternal line Posterior axillary line Midaxillary line Anterior axillary line Midclavicular line A Anterior view. B Right lateral view. Fig. 6.4 Pleural cavities and lungs projected onto the thoracic skeleton Cervical pleura (cupola) Costomediastinal recesses of pleural cavities Parietal pleura Right lung Left lung Inferior border of lung Inferior border of lung Costodiaphragmatic recesses of pleural cavities A Anterior view. Parietal pleura Left lung Right lung Costodiaphragmatic recesses of pleural cavities Posterior view. B 55 7 Thoracic Wall Thorax Thoracic Skeleton The thoracic skeleton consists of 12 thoracic vertebrae (p. 10), 12 pairs of ribs with costal cartilages, and the sternum. In addition to participating in respiratory movements, it provides a measure of protection to vital organs. The female thorax is generally narrower and shorter than the male equivalent. Fig. 7.1 Thoracic skeleton Clavicular notch Superior thoracic aperture Jugular notch Manubrium Sternal angle Sternum Body Xiphoid process Costal cartilage 1st rib Clavicular notch Costal margin (arch) Sternum Inferior thoracic aperture Vertebral body, T1 Spinous process, T1 Intervertebral disk A Anterior view. T1 spinous process Costal cartilage Costal margin (arch) Costal tubercle Costal angle Transverse process Costotransverse joint Spinous process, T12 12th rib C Posterior view. 56 Spinous process, L1 B Left lateral view. Vertebral body, T12 12th rib Vertebral body, L1 7 Thoracic Wall Fig. 7.2 Structure of a thoracic segment Superior view of 6th rib pair. Costal angle Spinous process Transverse process Costal tubercle Neck of rib Vertebral foramen Vertebral body Head of rib Body (shaft) of rib Elements of a thoracic segment Table 7.1 Vertebra Costal cartilage Head Bony part (costal bone) Rib Neck Costal tubercle Body (including costal angle) Costal part (costal cartilage) Sternum Sternum (articulates with costal cartilage of true ribs only; see Fig. 7.3) Fig. 7.3 Types of ribs Left lateral view. Rib type Ribs Anterior articulation True ribs 1–7 Sternum (costal notches) False ribs 8–10 Rib above Floating ribs 11, 12 None 57 Thorax Sternum & Ribs Fig. 7.4 Sternum The sternum is a dagger-like bone consisting of the manubrium (the handle), body (blade), and xiphoid process (tip of blade). The junction of the manubrium and body (the sternal angle) is typically elevated and marks the articulation of the second rib. The sternal angle (projected posteriorly to intersect with T4/5) is an important landmark for internal structures. Jugular notch Clavicular notch Manubrium Sternal angle Clavicular notch 1st costal notch Manubrium Body Sternal angle Xiphoid process Body A Anterior view. 2nd through 7th costal notches Xiphoid process B Left lateral view. The costal notches are sites of articulation with the costal cartilage of the true ribs (see Fig. 7.3). 58 Fig. 7.5 Ribs 12th rib Supraspinous fossa Right ribs, superior view. See pp. 298–299 for joints of the shoulder. 7 Thoracic Wall Scapular notch Acromion Acromioclavicular joint Dens of axis (C2) Atlas (C1) 1st rib Coracoid process Sternoclavicular joint Clavicle 5th rib 2nd rib Manubrium A Variations in rib size and shape. Costal tubercle Costal angle Crest of neck Neck Head Costal tubercle Crest of neck Costal tubercle Head Neck Head Tuberosity for serratus anterior Neck Costal angle Head Groove for subclavian a. Tubercle for anterior scalene Groove for subclavian v. 2nd rib Body (shaft) Body (shaft) B 1st rib. Most ribs have a costal groove along the inferior border (See Fig. 7.24), which protects the intercostal vessels and nerves. 11th rib 5th rib C Right ribs, superior view. 59 Thorax Joints of the Thoracic Cage The diaphragm is the chief muscle for quiet respiration (see p. 64). The muscles of the thoracic wall (see p. 62) contribute to deep (forced) inspiration. Fig. 7.6 Rib cage movement on the diagrams are longer than the blue ones (expiration dimensions) below. The downward movement of the diaphragm further increases the volume of the thoracic cavity. Full inspiration (red); full expiration (blue). In deep inspiration, there is an increase in transverse and anteroposterior (AP) dimensions, as well as the infrasternal angle. Note the red lines (inspiration dimensions) Infrasternal angle Infrasternal angle Inspiration Anteroposterior (AP) dimension Anteroposterior (AP) dimension Transverse thoracic dimension Transverse thoracic dimension Expiration A Anterior view. B Left lateral view. Axis of movement C Position of diaphragm during respiration. Blue line = expiration, red line = inspiration. Axis of movement Neck of rib Upper rib Increase in transverse dimension Lower rib Increase in Anteroposterior (AP) dimension DAxes of rib movement, superior view. 60 Fig. 7.7 Sternocostal joints 7 Thoracic Wall Anterior view with right half of sternum sectioned frontally. True joints are generally found only at ribs 2 to 5; ribs 1, 6, and 7 attach to the sternum by synchondroses. Clavicular notch 1st rib Sternum Fig. 7.8 Costovertebral joints Radiate sternocostal ligs. Two synovial joints make up the costovertebral articulation of each rib. The costal tubercle of each rib articulates with the costal facet of its accompanying vertebra (A). The head of most ribs articulates with the vertebra of its own number and the vertebra immediately superior. Ribs 1, 11, and 12 typically articulate only with their own vertebrae. Joint space Costal cartilage Costoxiphoid lig. Xiphoid process Superior articular facet Facet for rib tubercle Lateral costotransverse lig. Costotransverse joint Costal tubercle, articular surface Superior costotransverse lig. (cut) Costal tubercle Neck of 8th rib Costotransverse lig. Radiate lig. Joint of head of rib Intervertebral disk T8 Transverse process T5 Costotransverse lig. (cut) Costal facets Facet for rib tubercle A Costotransverse joint. Superior view with joints of the left rib transversely sectioned. Lateral costotransverse lig. (cut) Spinous process Intra-articular lig. Crest of rib head Intervertebral disk Radiate lig. Articular facets (on head of 7th rib) Superior costotransverse lig. Costal tubercle 8th rib (neck) T8 B Costovertebral joints. Left lateral view with the joint head of the 7th rib viewed in sagittal section.. 61 Thorax Thoracic Wall Muscle Facts the shoulder (see pp. 318–319), and the serratus posterior is discussed with the back (see p. 32). The muscles of the thoracic wall are primarily responsible for ribcage movement during ­respiration, although other muscles aid in deep inspiration: the pectoralis major and serratus anterior are discussed with Fig. 7.9 Muscles of the thoracic wall ④ ② ① ⑥ ⑦ ③ ⑤ ⑤ ⑥ B Intercostal muscles, anterior view. A Scalene muscles, anterior view. Muscle Intercostal mm. Origin Insertion Innervation ① Anterior scalene m. C3–C6 (transverse processes, anterior tubercles) 1st rib (anterior scalene tubercle) Anterior rami of C4–C6 spinal nn. ② Middle scalene m. C1–C2 (transverse processes) C3–C7 (transverse processes, posterior tubercles) 1st rib (posterior to groove for subclavian a.) Anterior rami of C3–C8 spinal nn. ③ Posterior scalene m. C5–C7 (transverse processes, posterior tubercles) 2nd rib (outer surface) Anterior rami of C6–C8 spinal nn. ④ External intercostal mm. Lower margin of rib to upper margin of next lower rib (courses obliquely forward and downward from costal tubercle to chondro-osseous junction) ⑤ Internal intercostal mm. ⑥ Innermost intercostal mm. 62 C Transversus thoracis, posterior view. Muscles of the thoracic wall Table 7.2 Scalene mm. ④ Lower margin of rib to upper margin of next lower rib (courses obliquely forward and upward from costal angle to sternum) Action ith ribs mobile: Elevates upper ribs W (inspiration) With ribs fixed: Flexes cervical spine to same side (unilateral); flexes neck (bilateral) Elevates ribs (inspiration); supports intercostal spaces; stabilizes chest wall 1st to 11th intercostal nn. Depresses ribs (expiration); supports intercostal spaces, stabilizes chest wall Subcostal mm. Lower margin of lower ribs to inner surface of ribs two to three ribs below Adjacent intercostal nn. Depresses ribs (expiration) ⑦ Transversus thoracis m. Sternum and xiphoid process (inner surface) 2nd to 6th intercostal nn. Weakly depresses ribs (expiration) 2nd to 6th ribs (costal cartilage, inner surface) Fig. 7.10 Muscles of the thoracic wall Atlas (C1) Anterior longitudinal lig. Posterior scalene Middle scalene 7 Thoracic Wall Anterior view. The external intercostal muscles are replaced anteriorly by the external intercostal membrane. The internal intercostal muscles are replaced posteriorly by the ­internal intercostal membrane. Axis (C2) Anterior scalene 1st rib Manubrium External intercostal muscles Radiate sternocostal ligs. External intercostal membrane Internal intercostal muscles Sternum External intercostal muscles Costal cartilage Anterior longitudinal lig. Posterior scalene Fig. 7.11 Transversus thoracis Middle scalene Anterior view with thoracic cage opened to expose posterior surface of anterior wall. The external and internal intercostal membranes Manubrium have been removed. Anterior scalene Innermost intercostal muscles Internal intercostal muscles External intercostal muscles Transversus thoracis Internal intercostal muscles Xiphoid process Costal cartilage Subcostal muscles Chondro-osseous junction 63 Thorax Diaphragm Fig. 7.12 Diaphragm Clavicle The diaphragm, which separates the thorax from the abdomen, has two asymmetric domes and three apertures (for the aorta, vena cava, and esophagus; see Fig. 7.13C). Scapula Diaphragm, sternal part (attaching posterior to the sternum) Caval opening Central tendon Diaphragm, costal part Diaphragm, left dome Diaphragm, right dome Diaphragm, lumbar part Xiphoid process Diaphragm, costal part 10th rib Sternum 12th rib Lumbocostal triangle Transverse process, L1 Aortic hiatus Diaphragm, lumbar part Right crus Transverse process, L1 B Posterior view. Left crus A Anterior view. Caval opening Esophageal hiatus Central tendon Right dome Left dome Median arcuate lig. Diaphragm, costal part Right crus Diaphragm, lumbar part Lateral arcuate lig. Left crus Aortic hiatus Quadratus lumborum C Coronal section with diaphragm in intermediate position. Table 7.3 Origin Costal part Medial arcuate lig. Transversus abdominis Insertion Innervation Action Central tendon Phrenic n. (C3–C5, cervical plexus) Principal muscle of respiration (diaphragmatic and thoracic breathing); aids in compressing abdominal viscera (abdominal press) 7th to 12th ribs (inner surface; lower margin of costal arch) Lumbar part Medial part: L1–L3 vertebral bodies, intervertebral disks, and anterior longitudinal lig. as right and left crura Sternal part Xiphoid process (posterior surface) Lateral parts: lateral and medial arcuate ligs. 64 Psoas minor Diaphragm Muscle Diaphragm Psoas major Caval opening Sternocostal triangle Sternum Diaphragm, sternal part Fig. 7.13 Diaphragm in situ Rectus abdominis 7 Thoracic Wall Central tendon Diaphragm, costal part Median arcuate lig. Aortic hiatus Esophageal hiatus External oblique Left crus Right crus Lumbocostal (Bochdalek’s) triangle Internal oblique Transversus abdominis Latissimus dorsi Quadratus lumborum Lateral arcuate lig. Psoas major Vertebral Intrinsic body back muscles Medial arcuate lig. Inferior view. A Sternum Diaphragm, sternal part Central tendon Caval opening Diaphragm, costal part Intercostal muscles Aortic hiatus Esophageal hiatus T8 Rib T8 Inferior vena cava Intrinsic back muscles Parietal pleura, costal part B Superior view. Esophagus T10 T12 Aorta C Diaphragmatic apertures, left lateral view. 65 Thorax Neurovasculature of the Diaphragm Fig. 7.14 Neurovasculature of the diaphragm Anterior view of opened thoracic cage. Inferior thyroid v. Left common carotid a. Left internal jugular v. Left external jugular v. Left subclavian a. and v. Left brachiocephalic v. Left phrenic n. Right phrenic n. Superior vena cava Internal thoracic a. Posterior intercostal vv. Accessory hemiazygous v. Azygos v. Pericardiacophrenic a. Hemiazygos v. Musculophrenic a. Superior phrenic aa. Left phrenic n. Inferior phrenic aa. Celiac trunk Inferior vena cava C3 Fig. 7.15 Innervation of the diaphragm C4 C5 Anterior view. The phrenic nerves lie on the lateral surfaces of the fibrous pericardium together with the pericardiacophrenic arteries and veins. Note: The phrenic nerves also innervate the pericardium. Anterior scalene Left phrenic n. Right phrenic n. Rib From parietal pleura, mediastinal part Intercostal mm. Pericardial brs. From parietal pleura, diaphragmatic part Phrenicoabdominal br. of phrenic n. Intercostal nn. Diaphragm Efferent (somatic motor) fibers 66 Afferent (somatic sensory) fibers Table 7.4 Blood vessels of the diaphragm Origin Vein Drainage Inferior phrenic aa. (chief blood supply) Abdominal aorta; occasionally from celiac trunk Inferior phrenic vv. Inferior vena cava Superior phrenic aa. Thoracic aorta Superior phrenic vv. Azygos v. (right side), hemiazygos v. (left side) Pericardiacophrenic vv. Internal thoracic vv. or brachiocephalic vv. Musculophrenic vv. Internal thoracic vv. Pericardiacophrenic aa. Internal thoracic aa. Musculophrenic aa. 7 Thoracic Wall Artery Fig. 7.16 Arteries and nerves of the diaphragm Note: The margins of the diaphragm receive sensory innervation from the lowest intercostal nerves. Sympathetic trunk Spinal cord Thoracic aorta Hemiazygos v. Intercostal n. Parietal pleura, costal part Azygos v. Parietal pleura, diaphragmatic part Left superior phrenic a. (from thoracic aorta) Right superior phrenic a. Parietal pleura, mediastinal part Inferior vena cava Esophagus Phrenic n., pericardiacophrenic a. and v. Parietal pleura, costal part A Superior view (~T8). Pericardium Musculophrenic a. (from internal thoracic a.) Internal thoracic a. and vv. Sternum Diaphragm, central tendon Rectus abdominis Diaphragm, costal part Esophageal hiatus Caval opening Phrenic n., phrenicoabdominal br. Right phrenic n. Celiac trunk Right inferior phrenic a. Left inferior phrenic a. Right superior suprarenal a. Left superior suprarenal a. Common hepatic a. Splenic a. External and internal oblique muscles, tranversus abdominis Greater splanchnic n. Diaphragm, lumbar part B Inferior view (~T12). Removed: Parietal peritoneum. Left phrenic n. Left ascending lumbar v. Quadratus lumborum Psoas major Abdominal aorta Spinal cord Lumbar vertebra Intrinsic back muscles 67 Thorax Arteries & Veins of the Thoracic Wall The posterior intercostal arteries anastomose with the anterior intercostal arteries to supply the structures of the thoracic wall. The posterior intercostal arteries branch from the thoracic aorta, with the exception of the 1st and 2nd, which arise from the superior intercostal artery (a branch of the costocervical trunk). Fig. 7.17 Arteries of the thoracic wall Left common carotid a. Anterior view. Table 7.5 Origin Superior thoracic a. Arteries of the thoracic wall Thyrocervical trunk Vertebral a. Thoracoacromial a. Left subclavian a. Axillary a. Branch Internal thoracic a. Lateral thoracic a. Axillary a. Subclavian a. Thoracoacromial a. 2nd intercostal a. Posterior intercostal aa. (1st and 2nd; see Fig. 4.1, p. 36) Thoracic aorta Superior thoracic a. Thoracic aorta Dorsal br. Thoracodorsal a. Posterior intercostal aa. (3rd through 12th) Posterior intercostal a. Collateral br. Anterior intercostal aa. Internal thoracic a. Lateral cutaneous br. Musculophrenic a. Lateral thoracic a. Superior epigastric a. Medial mammary br. Internal thoracic a. Anterior intercostal a. Anterior intercostal aa. Abdominal aorta Superior epigastric a. Musculophrenic a. 2nd and 3rd lumbar aa. Aortic bifurcation Fig. 7.18 Branches of the intercostal arteries Superior view. Table 7.6 Sternal brs. Anterior cutaneous br. Dorsal branch of posterior intercostal a. Artery Branches Supplies Spinal br. Spinal br. Internal thoracic a. Posterior intercostal a. Anterior intercostal a. Lateral cutaneous br. Branches of the intercostal arteries Dorsal br. Medial cutaneous br. Posterior intercostal aa. Thoracic aorta Medial cutaneous br. Lateral cutaneous br. Lateral cutaneous br. 68 Posterior thoracic wall Collateral br. Lateral thoracic wall Lateral cutaneous br.* Anterior thoracic wall Posterior intercostal a. Anterior intercostal aa. Spinal cord *The lateral mammary br. from the lateral cutaneous br. supplies the breast along with the medial mammary br. from the internal thoracic a. The intercostal veins drain primarily into the azygos system, but also into the internal thoracic vein. This blood ultimately returns to the heart via the superior vena cava. The intercostal veins follow a similar course to their arterial counterparts. However, the veins of the vertebral column form an external vertebral venous plexus that traverses the entire length of the spine (see p. 37). Anterior and posterior internal vertebral venous plexus Right internal jugular v. Left brachiocephalic v. Right brachiocephalic v. 7 Thoracic Wall Fig. 7.19 Veins of the thoracic wall Left subclavian v. Right subclavian v. Posterior intercostal vv. Internal thoracic v. Superior vena cava Anterior intercostal vv. Accessory hemiazygos v. Internal thoracic vv. Azygos v. Azygos v. Anterior external venous plexus Hemiazygos v. B Vertebral venous plexus, anterior view. Posterior intercostal vv. Inferior vena cava Subcostal v. (12th intercostal v.) 1st lumbar v. AAnterior view with rib cage opened. Internal jugular v. External jugular v. Subclavian v. Axillary v. Cephalic v. Superior vena cava Azygos v. Areolar venous plexus Thoracoepigastric v. Inferior vena cava Periumbilical vv. Common iliac v. Fig. 7.20 Superficial veins Anterior view. The thoracoepigastric veins are a potential superficial collateral venous drainage route in the event of superior or inferior vena cava obstruction. External iliac v. Superficial epigastric v. Superficial circumflex iliac v. External pudendal v. Femoral v. Great saphenous v. 69 Thorax Nerves of the Thoracic Wall Fig. 7.21 Intercostal nerves Anterior view. The 1st rib has been removed to reveal the 1st and 2nd intercostal nerves. 1st and 2nd intercostal nn. Posterior ramus Lateral cutaneous br. T1 Intercostobrachial nn. Anterior cutaneous br. 3rd and 4th intercostal nn. Anastomosis with medial brachial cutaneous n. Sternal brs. Subcostal n. (12th intercostal n.) Fig. 7.22 Cutaneous innervation of the thoracic wall Supraclavicular nn. Supraclavicular nn. Medial cutaneous brs. Anterior cutaneous brs. Spinal nn., dorsal rami Lateral cutaneous brs. Intercostal nn. Lateral cutaneous brs. Superior clunial nn. Iliohypogastric n., lateral cutaneous br. A Anterior view. 70 B Posterior view. Intercostal nn., lateral cutaneous brs. Superior view. The spinal nerve is formed by the union of posterior (dorsal) and anterior (ventral) roots. The posterior root contains sensory fibers and the anterior root contains motor fibers. The spinal nerve and all its subsequent branches are mixed nerves, containing both motor and sensory fibers. The spinal nerve exits the vertebral canal via the intervertebral foramen. Its posterior ramus innervates the skin and intrinsic muscles of the back; its anterior ramus forms the cervical, brachial, lumbar, and sacral plexuses, and the intercostal nerves. See p. 38 for more details. Posterior root Sensory (spinal) ganglion Fig. 7.24 Arrangement of intercostal neurovascular bundle Coronal section, anterior view. Right lung 8th rib Visceral pleura Intercostal v., a., and n. Anterior root Posterior ramus Gray ramus communicans White ramus communicans Anterior ramus (intercostal n.) Sympathetic ganglion Meningeal br. 7 Thoracic Wall Fig. 7.23 Spinal nerve branches Lateral cutaneous br. Parietal pleura, costal part Diaphragm Costal groove Endothoracic fascia External intercostal Liver Anterior cutaneous br. Internal intercostal Innermost intercostal Fig. 7.25 Dermatomes of the thoracic wall Landmarks: T4 generally includes the nipple; T6 innervates the skin over the xiphoid. C3 C5 C3 C4 T2 C4 T2 C5 T4 T6 L1 T 10 L1 A Anterior view. B Posterior view. 71 Thorax Neurovascular Topography of the Thoracic Wall Fig. 7.26 Anterior structures Axillary a. and v. Anterior view (see Chapter 4 for neurovasculature of the back). External jugular v. Deltoid Median n. Ulnar n. Lateral thoracic a. and v. Cephalic v. Thoracoepigastric v. Internal thoracic a. and v. Anterior cutaneous brs. Intercostal a., v., and n. Lateral cutaneous brs. Intercostal aa., vv., and nn. Superior epigastric a. and v. External oblique Internal oblique Rectus abdominis Clinical box 7.1 Insertion of a chest tube Abnormal fluid collection in the pleural space (e.g., pleural effusion due to bronchial carcinoma) may necessitate the insertion of a chest tube. Generally, the optimal puncture site in a sitting patient is at the level of the 4th or 5th intercostal space in the mid to anterior axillary line, immediately behind the lateral edge of the pectoralis major. The drain should always be introduced at the upper margin of a rib to avoid injuring the intercostal vein, artery, and nerve. See Clinical box 10.5 on p. 123 for details on collapsed lungs. Pectoralis major Pleural effusion Parietal pleura Costal groove Intercostal v., a., and n. Visceral pleura Endothoracic fascia Rib B Drainage tube is inserted perpendicular to chest wall. Chest tube Pleural space Puncture site Innermost intercostal A Coronal section, anterior view. 72 Internal and external intercostal muscles DAt the superior margin of the rib, the tube is passed through the intercostal muscles and advanced into the pleural cavity. C At ribs, the tube is angled and advanced parallel to the chest wall in the subcutaneous plane. 7 Thoracic Wall Fig. 7.27 Intercostal structures in cross section Transverse section, anterosuperior view. The relationship of the intercostal vessels in the costal groove, from superior to inferior, is vein, artery, and nerve (see clinical box, p. 72). Right superior phrenic a. Latissimus dorsi External intercostal Costal groove Intercostal n., collateral br. Intrinsic back muscles Intercostal v., posterior br. Spinal cord (with spinal ganglion) Internal intercostal Intercostal nn., anterior rami Innermost intercostal Posterior intercostal aa. and vv. Parietal pleura, costal part Azygos v. Central tendon of diaphragm Thoracic aorta Esophagus Serratus anterior Inferior vena cava Diaphragm Phrenic n., pericardiacophrenic a. and v. Pericardial sac Parietal pleura, diaphragmatic part Intercostal n., lateral cutaneous br. Musculophrenic a. (from internal thoracic a.) Internal thoracic a. and vv. Anterior perforating br. Sternum External oblique Intercostal n., anterior cutaneous br. 73 Thorax Female Breast The female breast, a modified sweat gland in the subcutaneous tissue layer, consists of glandular tissue, fibrous stroma, and fat. The breast extends from the 2nd to the 6th rib and is loosely attached to the p ­ ec- toral, axillary, and superficial abdominal fascia by connective tissue. The breast is additionally supported by suspensory ligaments. An extension of the breast tissue into the axilla, the axillary tail, is generally present. Fig. 7.28 Female breast Fig. 7.29 Mammary ridges Right breast, anterior view. Rudimentary mammary glands form in both sexes along the mammary ridges. Occasionally, these may persist in humans to form accessory nipples (polythelia), although only thoracic nipples normally remain. Nipple Areola Areolar glands Fig. 7.30 Blood supply to the breast Axillary a. and v. Subclavian a. and v. Internal thoracic a. and v. Lateral thoracic a. and v. Medial mammary brs. Perforating brs. Fig. 7.31 Sensory innervation of the breast Lateral mammary brs. Mammary brs. Supraclavicular nn. Intercostal nn., medial mammary brs. Intercostal nn., lateral mammary brs. 74 The glandular tissue is composed of 10 to 20 individual lobes, each with its own lactiferous duct. The gland ducts open on the elevated nipple at the center of the pigmented areola. Just proximal to the duct opening is a dilated portion called the lactiferous sinus. Areolar elevations are the openings of the areolar glands (sebaceous). The glands and lactiferous ducts are surrounded by firm, fibrofatty tissue with a rich blood supply. 7 Thoracic Wall Fig. 7.32 Structures of the breast Pectoral fascia Suspensory (Cooper’s) ligs. Pectoralis minor Mammary lobes Intercostal muscles Nipple Pectoralis major Lactiferous sinus Intercostal v., a., and n. Lactiferous duct Superficial thoracic fascia Interlobular connective tissue A Sagittal section along midclavicular line. Lobules Lactiferous duct Lactiferous sinus Acini Mammary lobes B Duct system and portions of a lobe, sagittal section. In the nonlactating breast (shown here), the lobules contain clusters of rudimentary acini. Terminal duct Terminal duct lobular unit (TDLU) C Terminal duct lobular unit (TDLU). The clustered acini composing the lobule empty into a terminal ductule; these structures are collectively known as the TDLU. 75 Thorax Lymphatics of the Female Breast ­relationship to the pectoralis minor (Table 7.7). The medial portion of the breast is drained by the parasternal lymph nodes, which are associated with the internal thoracic vessels. The lymphatic vessels of the breast (not shown) are divided into three systems: superficial, subcutaneous, and deep. These drain primarily into the axillary lymph nodes, which are classified based on their Fig. 7.33 Axillary lymph nodes Level II Level III Level I Interpectoral axillary l.n. Parasternal l.n. A Lymphatic drainage of the breast. See Table 7.7 for explanation of level I, II, and III. Supraclavicular l.n. Axillary a. Pectoralis major Subscapular axillary l.n. Central axillary l.n. Omohyoid, inferior belly (cut) Cervical l.n. Internal jugular v. Brachial v. Subclavian a. Biceps brachii Clavicle Apical axillary l.n. Basilic v. Pectoralis minor Brachial a. Interpectoral axillary l.n. Pectoralis major Cubital l.n. Pectoral axillary l.n. Axillary lymphatic plexus Brachial l.n. Supratrochlear l.n. Lateral thoracic v. Humeral axillary l.n. Latissimus dorsi B Anterior view. Table 7.7 Levels of axillary lymph nodes Level Position Lymph nodes (l.n.) Pectoral axillary l.n. I Lower axillary group Lateral to pectoralis minor Subscapular axillary l.n. Humeral axillary l.n. 76 II Middle axillary group Along pectoralis minor III Upper infraclavicular group Medial to pectoralis minor Central axillary l.n. Interpectoral axillary l.n. Apical axillary l.n. Clinical box 7.2 Stem cells in the intralobular connective tissue give rise to tremendous cell growth, necessary for duct system proliferation and acini differentiation. This makes the terminal duct lobular unit (TDLU) the most common site of origin of malignant breast tumors. Lobules 7 Thoracic Wall Breast cancer Lactiferous duct Lactiferous sinus ≈ 60% ≈15% ≈10% Acini Terminal duct ≈10% ≈ 5% Terminal duct lobular unit (TDLU) A Terminal duct lobular unit. B Origin of malignant tumors by quadrant. Tumors originating in the breast spread via the lymphatic vessels. The deep system of lymphatic drainage (level III) is of particular importance, although the parasternal lymph nodes provide a route by which tumor cells may spread across the midline. The survival rate in breast cancer correlates most strongly with the number of lymph nodes involved at the axillary nodal level. Metastatic involvement is gauged through scintigraphic mapping with radiolabeled colloids (technetium [Tc] 99m sulfur microcolloid). The downstream sentinel node is the first to receive lymphatic drainage from the tumor and is therefore the first to be visualized with radiolabeling. Once identified, it can then be removed (via sentinel lymphadenectomy) and histologically examined for tumor cells. This method is 98% accurate in predicting the level of axillary nodal involvement. Metastatic involvement 5-year survival rate Level I 65% Level II 31% Level III ~0% Nipple Normal mammogram. C DMammogram of invasive ductal carcinoma (irregular white areas, arrows). The large lesion has changed the architecture of the neighboring breast tissue. 77 8 Thoracic Cavity Thorax Divisions of the Thoracic Cavity The thoracic cavity is divided into three large spaces: the mediastinum (p. 90) and the two pleural (pulmonary) cavities (p. 112). Fig. 8.1 Thoracic cavity Coronal section, anterior view. Table 8.1 Thoracic inlet Major structures of the thoracic cavity Thymus, great vessels, trachea, esophagus, and thoracic duct Superior mediastinum Superior mediastinum Right lung in right pulmonary cavity Mediastinum Left lung in left pulmonary cavity Inferior mediastinum Diaphragm Pulmonary cavities Thoracic outlet Inferior mediastinum Anterior Thymus (especially in children) Middle Heart, pericardium, and roots of great vessels Posterior Thoracic aorta, thoracic duct, esophagus, and azygos venous system Right pulmonary cavity Right lung Left pulmonary cavity Left lung A Divisions of the thoracic cavity. Right common carotid a. Thyroid gland, right lobe Thyroid cartilage Internal jugular v. Left phrenic n. Recurrent laryngeal n. Right phrenic n. Brachial plexus Anterior scalene Left vagus n. Trachea Left subclavian a. and. v. Right vagus n. Internal thoracic a. and v. Brachiocephalic trunk First rib Left brachiocephalic v. Right brachiocephalic v. Aortic arch Superior vena cava Left vagus n. Thymus Left pulmonary a. Pericardiacophrenic a. and v., phrenic n. Parietal pleura, mediastinal part Left lung Right lung B Opened thoracic cavity. Removed: Thoracic wall; connective tissue of anterior mediastinum. 78 Fibrous pericardium Pericardiacophrenic a. and v., pericardial branches Phrenic n., pericardial branches Parietal pleura (diaphragmatic part) 8 Thoracic Cavity Fig. 8.2 Divisions of the mediastinum Esophagus (cervical part) Cervical part Thoracic inlet Thoracic part Esophagus (thoracic part) Trachea Sternum Anterior mediastinum Superior mediastinum Sternum Anterior mediastinum Posterior mediastinum Middle mediastinum Posterior mediastinum Esophagus Right lung Left lung Middle mediastinum Diaphragm Thoracic vertebra Descending aorta Transverse section, inferior view. B Midsagittal section, lateral view. A Fig. 8.3 Transverse sections of the thorax Computed tomography (CT) scan of thorax, inferior view. Superior vena cava Right and left main bronchi A Superior mediastinum. Ascending aorta Esophagus Inferior vena cava Esophagus Azygos v. Descending aorta Descending aorta B Inferior mediastinum. 79 Thorax Arteries of the Thoracic Cavity The arch of the aorta has three major branches: the brachiocephalic trunk, left common carotid artery, and left subclavian artery. After the aortic arch, the aorta begins its descent, becoming the thoracic aorta at the level of the sternal angle and the abdominal aorta once it passes through the aortic hiatus in the diaphragm. Fig. 8.4 Thoracic aorta Thyroid cartilage Right common carotid a. Anterior scalene Middle scalene Left common carotid a. Trachea Thyrocervical trunk Right vertebral a. Right subclavian a. Internal thoracic a. Left subclavian a. Esophagus Aortic arch 1st rib Brachiocephalic trunk Ascending aorta Bronchial a. Right main bronchus Left main bronchus Esophageal branch Posterior intercostal aa. Thoracic aorta Diaphragm Inferior phrenic a. Aortic hiatus Celiac trunk Abdominal aorta Lumbar a. A Thoracic aorta in situ, anterior view. Removed: Heart, lungs, portions of diaphragm. 80 Esophagus Left common carotid a. Brachiocephalic trunk Ascending aorta Left main bronchus Pulmonary trunk Left subclavian a. Aortic arch Table 8.2 The thoracic organs are supplied by direct branches from the thoracic aorta, as well as indirect branches from the subclavian arteries. Part of aorta Ascending aorta Branches Region supplied Right and left coronary aa. Heart Bronchi, trachea, esophagus Right subclavian a. Brachiocephalic trunk Left pulmonary a. See left subclavian a. Right common carotid a. Left common carotid a. Descending aorta B Parts of the aorta, left lateral view. Note: The aortic arch begins and ends at the level of the sternal angle (see p. 58). Branches of the thoracic aorta 8 Thoracic Cavity Trachea Head and neck Vertebral a. rch of A aorta Anterior intercostal aa. Anterior chest wall Thymic brs. Thymus Mediastinal brs. Posterior mediastinum Pericardiacophrenic a. Pericardium, diaphragm Thyrocervical trunk Inferior thyroid a. Esophagus, trachea, thyroid gland Costocervical trunk Superior intercostal a. Chest wall Internal thoracic a. Left subclavian a. Descending aorta Visceral brs. Parietal brs. Bronchi, trachea, esophagus Posterior intercostal aa. Posterior chest wall Superior phrenic aa. Diaphragm Clinical box 8.1 Aortic dissection A tear in the inner wall (intima) of the aorta allows blood to separate the layers of the aortic wall, creating a “false lumen” and potentially resulting in life-threatening aortic rupture. Symptoms are dyspnea (shortness of breath) and sudden onset of excruciating pain. Acute aortic dissections occur most often in the ascending aorta and generally require surgery. More distal aortic dissections may be treated conservatively, provided there are no complications (e.g., obstruction of blood supply to the organs, in which case a stent may be inserted to restore perfusion). Aortic dissections occurring at the base of a coronary artery may cause myocardial infarction. “False lumen” Ascending aorta Intima “False lumen” Descending aorta A Aortic dissection. Parts of the intima are still attached to the connective tissue in the wall of the aorta (arrow). B The flow in the coronary arteries is intact (arrow). 81 Thorax Veins of the Thoracic Cavity The superior vena cava is formed by the union of the two brachio­ cephalic veins at the level of the T2–T3 junction. It receives blood drained by the azygos system (the inferior vena cava has no tributaries in the thorax). Fig. 8.5 Superior vena cava and azygos system Left internal jugular v. Right supreme intercostal v. Anterior scalene Middle scalene Right subclavian v. 1st rib Right internal thoracic v. Left external jugular v. Left subclavian v. Inferior thyroid v. Left brachiocephalic v. Right brachiocephalic v. Azygos v. Superior vena cava Accessory hemiazygos v. Posterior intercostal vv. Hemiazygos v. Diaphragm, central tendon Caval opening Diaphragm, costal part Esophageal hiatus Right ascending lumbar v. Left ascending lumbar v. Aortic hiatus Inferior vena cava Lumbar vv. A Veins of the thoracic cavity (viscera removed), anterior view of opened thorax (posterior thoracic wall). 82 Thoracic tributaries of the superior vena cava Table 8.3 Major vein Superior vena cava Right subclavian v. Left pulmonary vv. Right brachiocephalic v. Brachiocephalic vv. Inferior thyroid v. Esophagus, trachea, thyroid gland External jugular vv. Subclavian vv. Head, neck, upper limb Supreme intercostal vv. Pericardial vv. Left superior intercostal v. Azygos system (left side: accessory hemiazygos v.; right side: azygos v.) B Projection of venae cavae onto chest, anterior view. Region drained Internal jugular vv. Inferior vena cava Right pulmonary vv. Tributaries 8 Thoracic Cavity Left brachiocephalic v. Right internal jugular v. Trachea, bronchi, esophagus Visceral brs. Posterior intercostal vv. Parietal brs. Superior phrenic vv. Right superior intercostal v. Internal thoracic v. Inner chest wall and diaphragm Thymic vv. Thymus Mediastinal tributaries Posterior mediastinum Anterior intercostal vv. Anterior chest wall Pericardiacophrenic v. Pericardium Musculophrenic v. Diaphragm Note: Structures of the superior mediastinum may also drain directly to the brachiocephalic veins via the tracheal, esophageal, and mediastinal veins. Fig. 8.6 Azygos system Anterior view. Right internal jugular v. Inferior thyroid v. Left brachiocephalic v. Right subclavian v. Superior vena cava Azygos v. Accessory hemiazygos v. Posterior intercostal vv. Hemiazygos v. Hepatic vv. Diaphragm Left renal v. Right testicular/ ovarian v.* Lumbar vv. Left ascending lumbar v. Right ascending lumbar v. Left common iliac v. Inferior vena cava *The left testicular/ovarian vein drains to the left renal vein. 83 Thorax Lymphatics of the Thoracic Cavity The body’s chief lymph vessel is the thoracic duct. Beginning in the abdomen at the level of L1 at the cisterna chyli, the thoracic duct empties into the junction of the left internal jugular and subclavian veins. The right lymphatic duct drains to the right junction of the internal jugular and subclavian veins. Fig. 8.7 Lymphatic trunks in the thorax Anterior view of opened thorax. Common carotid a. Internal jugular v. Jugular trunk Subclavian a. Jugular trunk Thoracic duct Right lymphatic duct Subclavian trunk Right subclavian v. Brachiocephalic trunk Right brachiocephalic v. Superior vena cava Bronchomediastinal trunk Subclavian trunk Left subclavian v. Left brachiocephalic v. Bronchomediastinal trunk Ascending aorta Thoracic aorta Accessory hemiazygos v. Thoracic duct Diaphragm Intercostal lymphatics Azygos v. Hemiazygos v. Aortic hiatus Celiac trunk Abdominal aorta Cisterna chyli Left lumbar trunk Right lumbar trunk 84 Fig. 8.8 Lymphatic drainage pattern Fig. 8.9 Lymphatic pathways in the thorax Right jugular trunk Right lymphatic duct Thoracic duct 8 Thoracic Cavity Head and neck Left jugular trunk Thoracic duct Left internal jugular v. Right lymphatic duct Right subclavian trunk Left subclavian trunk Left subclavian v. Left bronchomediastinal trunk Right bronchomediastinal trunk Anterior mediastinum Paravertebral I.n. Posterior thoracic wall Anterior intercostal spaces Anterior thoracic wall Mammary gland Parasternal I.n. Posterior intercostal spaces Paramammary I.n. Superior mediastinum Brachiocephalic I.n. Pre-pericardial I.n. Lateral pericardial I.n. Paraesophageal I.n. Paratracheal I.n. Tracheobronchial I.n. Bronchopulmonary I.n. Intrapulmonary I.n. Superior phrenic I.n. Diaphragm Cisterna chyli Parasternal l.n. Abdomen, pelvis, and lower limb Tracheobronchial l.n. Lymphatics in trunk wall Bronchopulmonary l.n. Intrapulmonary l.n. Intercostal l.n. Paraesophageal l.n. Paratracheal l.n. Fig. 8.10 Thoracic lymph nodes Transverse section at the level of the tracheal bifurcation (T4–T5), superior view. The thoracic lymph nodes can be divided into three broad groups: nodes of the thoracic wall (pink), pulmonary nodes (blue), and mediastinal nodes (green). For details of lymphatics of the mediastinum, see pp. 110–111. 85 Thorax Nerves of the Thoracic Cavity Thoracic innervation is mostly autonomic, arising from the para­ vertebral sympathetic trunks and parasympathetic vagus nerves. There are two exceptions: the phrenic nerves innervate the pericardium and diaphragm (p. 66) and the intercostal nerves innervate the thoracic wall (p. 70). Left vagus n. Right vagus n. Fig. 8.11 Nerves in the thorax Anterior view of opened thorax. Sympathetic trunk, thoracic ganglion Right phrenic n. Left phrenic n. Posterior intercostal nn. A Thoracic innervation. Trachea Esophagus, cervical part Common carotid a. Sympathetic trunk, middle cervical ganglion Scalene mm. Right subclavian a. Brachial plexus Right vagus n. Left subclavian a. Right recurrent laryngeal n. 1st rib Brachiocephalic trunk Left vagus n. Left recurrent laryngeal n. Posterior intercostal a. Aortic arch Intercostal n. Esophagus, thoracic part Thoracic aorta Sympathetic trunk Anterior esophageal plexus Sympathetic trunk Innermost intercostals Greater splanchnic n. Diaphragm Anterior vagus br. B Nerves of the thorax in situ. Lungs, pericardial sac, heart and costal pleura removed. Note: The recurrent laryngeal nerves have been slightly anteriorly retracted; normally, they occupy the groove 86 Stomach between the trachea and the esopha­gus, making them vulnerable during thyroid gland surgery. The autonomic nervous system innervates smooth muscle, cardiac muscle, and glands. It is subdivided into the sympathetic (red) and parasympathetic (blue) nervous systems, which together regulate blood flow, secretions, and organ function. Sympathetic nervous system Parasympathetic nervous system Superior cervical ganglion Middle cervical ganglion Stellate ganglion T1 Vagus n. (CN X) T2 T3 Superior laryngeal n. Cervical cardiac nn. T4 8 Thoracic Cavity Fig. 8.12 Sympathetic and parasympathetic nervous systems in the thorax Larynx T5 T6 T7 Pharyngeal plexus T8 T9 External carotid plexus T10 T11 Internal carotid plexus T12 Recurrent laryngeal n. L1 Common carotid plexus L2 Esophageal plexus Sympathetic trunk Vertebral plexus Greater and lesser splanchnic n. Subclavian plexus Thoracic aortic plexus Pulmonary plexus Pulmonary plexus Cardiac plexus Cardiac brs. To abdomen Table 8.4 Peripheral sympathetic nervous system Origin of preganglionic fibers* Ganglion cells Course of postganglionic fibers Follow intercostal nn. Spinal cord Sympathetic trunk Vagal trunks Sympathetic preganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Target Table 8.5 Origin of preganglionic fibers Blood vessels and glands in chest wall Accompany intrathoracic aa. Visceral targets Gather in greater and lesser splanchnic nn. Abdomen *The axons of preganglionic neurons exit the spinal cord via the anterior roots and synapse with postganglionic neurons in the sympathetic ganglia. Brainstem Peripheral parasympathetic nervous system Course of preganglionic motor axons* Vagus n. (CN X) Target Cardiac brs. Cardiac plexus Esophageal brs. Esophageal plexus Tracheal brs. Trachea Bronchial brs. Pulmonary plexus (bronchi, pulmonary vessels) *The ganglion cells of the parasympathetic nervous system are scattered in microscopic groups in their target organs. The vagus n. thus carries the preganglionic motor axons to these targets. CN = cranial n. 87 9 Mediastinum Thorax Mediastinum: Overview The mediastinum is the space in the thorax between the pleural sacs of the lungs. It is divided into two parts: superior and inferior. The inferior Fig. 9.1 Divisions of the mediastinum Table 9.1 mediastinum is further divided into anterior, middle, and posterior portions. Contents of the mediastinum ● Superior mediastinum Esophagus (cervical part) Cervical part Thoracic part Thoracic inlet Esophagus, thoracic part Posterior mediastinum Diaphragm A Schematic. Esophageal inlet Esophagus, cervical part ● Middle • Thymus • Trachea • Esophagus • Esophagus • Smaller vessels • Ascending aorta • Pulmonary trunk and brs. • Pericardiacophrenic aa. • Thoracic aorta and brs. Arteries • Aortic arch • Brachiocephalic trunk • Left common carotid a. • Left subclavian a. Veins and lymph vessels • Superior vena cava •B rachiocephalic vv. • Thoracic duct and right lymphatic duct • Smaller vessels, lymphatics, and l.n. • Superior vena cava • Azygos v. • Pulmonary vv. • Pericardiacophrenic vv. • Azygos v. • Accessory hemiazygos and hemiazygos vv. •T horacic duct • None • Phrenic nn. • Vagus nn. Nerves • Vagus nn. • Left recurrent laryngeal n. • Cardiac nn. • Phrenic nn. Thyroid cartilage Trachea Pretracheal layer Brachiocephalic l. n. Azygos v. Left main bronchus, origin ● Posterior • Heart • Pericardium Trachea Anterior mediastinum Middle mediastinum ● Anterior • Thymus, inferior aspects (especially in children) Organs Superior mediastinum Sternum Inferior mediastinum Investing layer Deep cervical fascia Left brachiocephalic v. Manubrium Tracheobronchial l. n. Right pulmonary a. Esophagus, thoracic part Left atrium Ascending aorta Thymus (retrosternal fat pad) Aortic valve Sternum Pericardial cavity Superior phrenic l. n. Diaphragm Liver B Midsagittal section, right lateral view. 88 Site of attachment between liver and diaphragm (bare area) Xiphoid process Thyroid gland, right lobe Fig. 9.2 Contents of the mediastinum Thyroid cartilage Anterior scalene Vagus n. (CN X) Left recurrent laryngeal n. Internal thoracic a. and v. Inferior thyroid v. Thymus A Anterior view. The thymus extends into the anterior division of the inferior mediastinum and grows throughout childhood. At puberty, high levels of circulating sex hormones cause the thymus to atrophy leaving indistinguishable pieces embedded in the fat that now occupies the anterior mediastinum. 9 Mediastinum Trachea Left common carotid a. Phrenic n. Left vagus n. Aorta Superior vena cava Pericardiacophrenic a. and v., phrenic n. Left recurrent laryngeal n. Left pulmonary a. Brachial plexus Left internal jugular v. Parietal pleura, mediastinal part Parietal pleura, diaphragmatic part Left subclavian a. and v. Left brachiocephalic v. Parietal pleura, cervical part Aortic arch Ligamentum arteriosum Left pulmonary a. Superior and inferior lobar bronchi Left pleural cavity Superior vena cava Diaphragm Attachment between Fibrous fibrous pericardium and pericardium central tendon of the diaphragm Right pulmonary vv. Pulmonary trunk Thoracic aorta Parietal pleura, mediastinal part Right pleural cavity Inferior pharyngeal constrictor Left common carotid a. Left internal jugular v. Pericardiacophrenic Caval Esophagus, Fibrous a. and v., phrenic n. opening thoracic part pericardium Left subclavian a. and v. Aortic arch Parietal pleura, diaphragmatic part Thyroid gland, right lobe Esophagus, cervical part Superior vena cava Trachea Azygos v. Right main bronchus Left pulmonary a. Fibrous pericardium, left atrium Left pulmonary vv. B Anterior view with lungs, heart, pericardium, and thymus removed. Right pulmonary a. Esophagus, thoracic part Right pulmonary vv. Thoracic aorta Fibrous pericardium, left ventricle Esophageal hiatus Diaphragm Fibrous pericardium, right atrium Inferior vena cava (in caval opening) Posterior intercostal aa. C Posterior view. 89 Thorax Mediastinum: Structures Fig. 9.3 Mediastinum Clavicle 1st rib White and gray rami communicantes Intercostal v., a., and n. Brachiocephalic l.n. Right vagus n. Azygos v. Sympathetic trunk, thoracic ganglion Superior lobar bronchus Right pulmonary a. Common trunk of middle and inferior lobar bronchi Esophagus Greater splanchnic n. Brachial plexus Right subclavian a. and v. Brachiocephalic trunk Right brachiocephalic v. Right recurrent laryngeal n. Left brachiocephalic v. Trachea Superior vena cava Right phrenic n. Mediastinal pleura Thymus (retrosternal fat pad) Fibrous pericardium Right pulmonary vv. Phrenic n., pericardiacophrenic a. and v. Parietal pleura, costal part Posterior intercostal v. and a., intercostal n. Intercostal mm. A Right lateral view, parasagittal section. Note the many structures passing between the superior and inferior (middle and posterior) mediastinum. 90 Diaphragm (covered by parietal pleura, diaphragmatic part) 9 Mediastinum Clavicle 1st rib Brachial plexus Left subclavian a. and v. Esophagus Left superior intercostal v. Left vagus n. Ligamentum arteriosum Left phrenic n. Left pulmonary a. Left pulmonary vv. Parietal pleura, mediastinal part Lateral pericardial l.n. Left vagus n. Phrenic n., pericardiacophrenic a. and v. Intercostal v., a., and n. Thoracic duct Aortic arch Left recurrent laryngeal n. Sympathetic trunk Accessory hemiazygos v. Rami communicantes Left main bronchus Thoracic aorta (descending aorta) Splanchnic nn. Parietal pleura, costal part Hemiazygos v. Greater splanchnic n. Superior phrenic l.n. Diaphragm (covered by parietal pleura, diaphragmatic part) Intercostal mm. Posterior intercostal v. and a., intercostal n. B Left lateral view, parasagittal section. Removed: Left lung and parietal pleura. Revealed: Posterior mediastinal structures. 91 Thorax Heart: Functions & Relations The heart pumps the blood: unoxygenated blood to the lungs and oxygenated blood throughout the body. It is located posterior to the sternum in the middle portion of the mediastinum in the pericardial cavity, located between the right and left pleural cavities containing the lungs. The apex of the cone-shaped heart points anteriorly and to the left in the thoracic cavity. Fig. 9.4 Circulation Fig. 9.5 Topographical relations of the heart Oxygenated blood is shown in red; deoxygenated blood in blue. See p. 104 for prenatal circulation. Right common carotid a. Upper body circulation Left internal jugular v. Right brachiocephalic v. Left subclavian a. and v. Ascending aorta Superior vena cava Pulmonary trunk Diaphragm Cardiac apex Pulmonary circulation Pulmonary v. Pulmonary a. Superior vena cava Ascending aorta Right atrium Left atrium Aorta A Projection of the heart and great vessels onto chest, anterior view. Left ventricle Right ventricle Hepatic vv. Portal v. Inferior vena cava Portal circulation Trachea Brachiocephalic trunk Sternum, manubrium Left common carotid a. Left subclavian a. Superior vena cava Left main bronchus 2nd rib Lower body circulation Aortic arch Pulmonary trunk Left pulmonary vv. Sternum, body Thoracic aorta Esophagus Pericardial sac Diaphragm Abdominal aorta B Left lateral view. Removed: Left thoracic wall and left lung. 92 Stomach Fig. 9.6 Heart in situ Left lung Superior vena cava Serous pericardium, parietal layer Fibrous pericardium (= external layer) Parietal pleura, mediastinal part 9 Mediastinum Aortic arch Cardiac surface Serous pericardium, visceral layer (epicardium) A Anterior view of the opened thorax with the thymus removed and flaps of the anterior layer of the pericardial sac reflected to reveal the heart. Right brachiocephalic v. Diaphragm Brachiocephalic trunk Right phrenic n. Left brachiocephalic v. Left vagus n. Right lung Aortic arch Ligamentum arteriosum Superior vena cava Left pulmonary a. Ascending aorta Left phrenic n. Pulmonary trunk Parietal pleura, mediastinal part Left auricle Right auricle Anterior interventricular a. (LAD) Left ventricle Cardiac apex Diaphragm Fibrous pericardium Right ventricle Stomach B Anterior view of the opened thorax with thymus and anterior pericardium removed to reveal the heart. 93 Thorax Pericardium Fig. 9.7 Posterior pericardial cavity Anterior view of opened thorax with the anterior pericardium removed. The heart has been partially elevated to reveal the posterior pericardial cavity and the oblique pericardial sinus. Left vagus n. Superior vena cava Pericardiacophrenic a. and v., left phrenic n. Ascending aorta Pulmonary trunk Left auricle Left pulmonary vv. Heart, diaphragmatic surface Oblique pericardial sinus Right pulmonary v. Coronary sinus Inferior vena cava Fig. 9.8 Posterior pericardium Anterior view of the opened thorax with the anterior pericardium and heart removed to reveal the posterior pericardium and the oblique pericardial sinus. The transverse pericardial sinus is the passage between the reflections of the serous layer of the pericardium around the arterial and venous great vessels of the heart. Left recurrent laryngeal n. Ligamentum arteriosum Left vagus n. Pulmonary trunk Ascending aorta Left phrenic n. Transverse pericardial sinus Left pulmonary vv. Superior vena cava Right pulmonary vv. Inferior vena cava Parietal pleura, mediastinal part Oblique pericardial sinus Serous pericardium, parietal layer Fibrous pericardium Sternum 94 Attachment of fibrous pericardium to central tendon of diaphragm Fig. 9.9 Posterior relations of the heart Left vagus n. Superior vena cava Left phrenic n. Ascending aorta Left pulmonary a. Cut edge of fibrous pericardium surrounding origin of a. Parietal pleura, mediastinal part Left pulmonary vv. Cut edge of fibrous pericardium surrounding termination of vv. Posterior vagal trunk Anterior esophageal plexus Esophagus Anterior vagal trunk Inferior vena cava Sternum Fig. 9.10 Pericardium, pericardial cavity, and transverse pericardial sinus Sagittal section through the mediastinum. The fibrous pericardium is attached to the central tendon of the diaphragm and is continuous superiorly with the outer layer of the great vessels. The parietal layer of serous pericardium lines the inner surface of the fibrous pericardium and the visceral layer adheres to the heart. The pericardial cavity, the space between the parietal and visceral layers of serous pericardium around the heart, is filled with a thin layer of serous fluid that allows for frictionless movement. Where the parietal and visceral layers of serous pericardium reach and reflect around the great vessels, they are continuous with one another. The passage between the arterial and venous reflections of the serous pericardium is the transverse pericardial sinus. 9 Mediastinum Anterior view of the opened thorax with the anterior pericardium and heart removed and a window cut in the posterior pericardium to reveal the structures immediately posterior to the heart. This shows the close relationship of the esophagus to the heart, which is used in the transesophageal sonogram to assess the left atrium of the heart. Attachment of fibrous pericardium to central tendon of diaphragm Trachea Esophagus Left brachiocephalic v. Ascending aorta Right pulmonary a. Transverse pericardial sinus Pericardial cavity Aortic valve Left atrium Parietal layer Visceral layer Serous pericardium Attachment of fibrous pericardium to central tendon of diaphragm Superior phrenic l.n. Attachment of liver (bare area) to diaphragm Clinical box 9.1 Cardiac Tamponade Rapid increases of fluid or blood within the pericardial sac inhibits full expansion of the heart, reducing cardiac blood return, thus decreasing cardiac output. This condition, cardiac tamponade (compression), is potentially fatal, unless relieved. The fluid or blood must first be removed to restore cardiac function and then the cause of the fluid or blood accumulation corrected. 95 Thorax Heart: Surfaces & Chambers Note the reflection of visceral serous pericardium to become parietal serous pericardium. Aortic arch Ligamentum arteriosum Brachiocephalic trunk Fig. 9.11 Surfaces of the heart The heart has three surfaces: anterior (sternocostal), posterior (base), and inferior (diaphragmatic). Left pulmonary a. Right pulmonary a. Left pulmonary vv. Superior vena cava Pulmonary trunk Ascending aorta Right auricle Right atrium Coronary (right atrioventricular) sulcus Left auricle Fibrous pericardium (cut edge) Anterior interventricular sulcus Left ventricle Right ventricle Left common carotid a. Left subclavian a. Left subclavian a. Left common carotid a. Inferior vena cava Brachiocephalic trunk Anterior (sternocostal) surface. A Aortic arch Left pulmonary a. Cardiac apex Superior vena cava Left pulmonary vv. Right pulmonary a. Left auricle Right pulmonary vv. Left atrium Right atrium Left ventricle Visceral layer of serous pericardium (reflected edge) Coronary sinus Posterior surface (base). B Inferior vena cava Aortic arch Left pulmonary a. Left pulmonary vv. Superior vena cava Right pulmonary a. Right pulmonary vv. Left atrium Right atrium Coronary sinus Inferior vena cava Crux of heart Left ventricle Cardiac apex Inferior (diaphragmatic) surface. C 96 Right ventricle Posterior interventricular sulcus Aortic arch Fig. 9.12 Chambers of the heart Ligamentum arteriosum 9 Mediastinum Pulmonary trunk Left pulmonary vv. Right pulmonary a. Superior vena cava Valve of pulmonary trunk, cusps Conus arteriosus (infundibulum) Supraventricular crest Septal papillary m. Right atrium Left ventricle Coronary sulcus Right atrioventricular valve, anterior cusp Interventricular septum Trabeculae carneae Inferior vena cava Tendinous cords Anterior papillary m. Cardiac apex Posterior papillary m. A Right ventricle, anterior view. Note the supraventricular crest, which marks the adult boundary between the embryonic ventricle and the bulbus cordis (now conus arteriosus). Septomarginal trabecula (moderator band) Ascending aorta Superior vena cava Pulmonary trunk Right pulmonary a. Right auricle Left atrium Terminal crest Right pulmonary vv. Pectinate mm. Right ventricle Interatrial septum Right atrioventricular orifice with atrioventricular valve Limbus of oval fossa Oval fossa Inferior vena cava Valve of inferior vena cava Valve of coronary sinus B Right atrium, right lateral view. Left pulmonary a. Aortic arch Pulmonary trunk Right pulmonary a. Left auricle Pectinate mm. Left superior pulmonary v. Anterior papillary m. Valve of oval fossa Left atrium Trabeculae carneae of interventricular septum Interatrial septum Tendinous cords Cardiac apex Inferior vena cava Posterior papillary m. Left atrioventricular valve, cusp C Left atrium and ventricle, left lateral view. Note the irregular trabeculae carneae characteristic of the ventricular wall. 97 Thorax Heart: Valves The cardiac valves are divided into two types: semilunar and atrio­ ventricular. The two semilunar valves (aortic and pulmonary) located at the base of the two great arteries of the heart regulate passage of Pulmonary valve Right cusp Anterior cusp blood from the ventricles to the aorta and pulmonary trunk. The two atrioventricular valves (left and right) lie at the interface between the atria and ventricles. Fig. 9.13 Cardiac valves Left cusp Posterior cusp Left cusp Anterior interventricular a. (LAD) Right coronary a. Left coronary a. Anterior cusp Circumflex a. Left atrioventricular (bicuspid or mitral) valve Plane of cardiac valves, superior view. Removed: Atria and great arteries. Aortic valve Right cusp Anterior cusp Right atrioventricular (tricuspid) valve Septal cusp Posterior cusp Posterior cusp Coronary sinus AVentricular diastole (relaxation of the ventricles). Closed: Semilunar valves. Open: Atrioventricular valves. Pulmonary valve Right cusp Anterior cusp Left cusp Anterior interventricular a. (LAD) Right coronary a. Left coronary a. Anterior cusp Circumflex a. Fibrous ring of pulmonary valve Left fibrous trigone Left atrioventricular valve Anterior cusp Septal cusp Posterior cusp Right atrioventricular valve Posterior cusp Tendon of conus Fibrous ring of aortic valve Aortic valve Right cusp Posterior cusp Left cusp Coronary sinus Ventricular systole (contraction of the ventricles). B Closed: Atrioventricular valves. Open: Semilunar valves. Right fibrous trigone Table 9.2 Left fibrous anulus Opening for the bundle of His Right fibrous anulus Cardiac skeleton, superior view. The cardiac skeleton is formed by C dense fibrous connective tissue. The fibrous anuli (rings) and intervening trigones separate the atria from the ventricles. This provides mechanical ­stability, electrical insulation (see p. 102 for cardiac conduction system), and an attachment point for the cardiac muscles and valve cusps. 98 Position and auscultation sites of cardiac valves Valve Anatomical projection Auscultation site Aortic valve Left sternal border (at level of 3rd rib) Right 2nd intercostal space (at sternal margin) Pulmonary valve Left sternal border (at level of 3rd costal cartilage) Left 2nd intercostal space (at sternal margin) Left atrioventricular valve Left 4th/5th costal cartilage Left 5th intercostal space (at midclavicular line) or cardiac apex Right atrioventricular valve Sternum (at level of 5th costal cartilage) Left 5th intercostal space (at sternal margin) Fig. 9.14 Semilunar valves Fig. 9.15 Atrioventricular valves Valves have been longitudinally sectioned and opened. Nodule Commissural cusp Lunule Opening of right coronary a. Opening of left coronary a. Aortic sinus Left atrium 9 Mediastinum Ascending aorta Anterior view during ventricular systole. Posterior cusp Anterior cusp Left cusp Right cusp Interatrial septum Interventricular septum Posterior cusp Tendinous cords Membranous part Posterior papillary m. Muscular part Anterior papillary m. Posterior papillary m. A Aortic valve. Cardiac apex A Left atrioventricular valve. Nodule Pulmonary trunk Opening of right pulmonary a. Right cusp Anterior cusp Anterior cusp Lunule Left cusp Trabeculae carnae B Pulmonary valve. Posterior cusp Tendinous cords Posterior papillary m. Septal cusp Septal papillary m. Interventricular septum Anterior papillary m. Septomarginal trabecula B Right atrioventricular valve. Clinical box 9.2 Auscultation of the cardiac valves Heart sounds, produced by closure of the semilunar and atrioventricular valves, are carried by the blood flowing through the valve. The resulting sounds are therefore best heard “downstream,” at defined auscultation sites (dark circles on diagram). Valvular heart disease causes turbulent blood flow through the valve; this produces a murmur that may be detected in the region of ascultation. Aortic valve Right atrioventricular valve Pulmonary valve Left atrioventricular valve 99 Thorax Arteries & Veins of the Heart Fig. 9.16 Coronary arteries and cardiac veins Pulmonary valve Superior vena cava Superior left pulmonary v. Atrial brs. Ascending aorta with aortic sinus Left auricle (atrial appendage) Left coronary a. Br. to sinoatrial node Circumflex br. Right auricle (atrial appendage) Left marginal a. and v. Right coronary a. Great cardiac v. Conus br. Anterior interventricular br. (left anterior descending) Atrial br. Small cardiac v. Right marginal a. and v. Lateral br. Anterior vv. of right ventricle Oblique v. of left atrium Atrial brs. Left atrium Left ventricle Superior vena cava Right ventricle Left pulmonary vv. Cardiac apex A Anterior view. Br. to sinoatrial node Right pulmonary vv. Circumflex br. Great cardiac v. Right atrium Left marginal v. Coronary sinus Inferior vena cava Right coronary a. Left posterior ventricular v. Small cardiac v. Right posterolateral a. Right ventricle Posteroinferior view. Note: The right and B left coronary arteries typically anastomose posteriorly at the left atrium and ventricle. Posterior interventricular a. (posterior descending a.) Left ventricle Middle cardiac v. Table 9.3 Branches of the coronary arteries Left coronary artery Circumflex br. • Atrial br. • Left marginal a. • Posterior left ventricular br. Anterior interventricular br. (left anterior descending) • Conus br. • Lateral br. • Interventricular septal brs. AV, atrioventricular; SA, sinoatrial. 100 Right coronary artery Br. to SA node Conus br. Atrial br. Right marginal a. Posterior interventricular br. (posterior descending) • Interventricular septal brs. Br. to AV node Right posterolateral a. Table 9.4 Vein Divisions of the cardiac veins Tributaries Anterior cardiac vv. (not shown) Drainage to Right atrium Anterior interventricular v. Great cardiac v. Left marginal v. Oblique v. of left atrium Left posterior ventricular v. Middle cardiac v. (posterior interventricular v.) Small cardiac v. Anterior vv. of right ventricle Right marginal v. Coronary sinus Fig. 9.17 Distribution of the coronary arteries Left coronary a. Left ventricle Interventricular septum Right ventricle Circumflex br. Posterior left ventricular br. Right coronary a. Right coronary a. Posterior interventricular br. Clinical box 9.3 Disturbed coronary blood flow Although the coronary arteries are connected by structural anastomoses, they are end arteries from a functional standpoint. The most frequent cause of deficient blood flow is athero­sclerosis, a narrowing of the coronary lumen due to plaque-like deposits on the vessel wall. When the decrease in luminal size (stenosis) reaches a critical point, coronary blood flow is restricted, causing chest pain (angina pectoris). Initially, this pain is induced by physical effort, but eventually it persists at rest, often radiating to characteristic sites (e.g., medial side of left upper limb, left side of head and neck). A myocardial infarction occurs when deficient blood supply causes myocardial tissue to die (necrosis). The location and extent of the infarction depends on the stenosed vessel (see A–E, after Heinecker). 9 Mediastinum Anterior and posterior views of the heart, with superior views of transverse sections through the ventricles. The “distribution” of the coronary arteries refers to the area of the myocardium supplied by each artery, as seen in the transverse views, but the term “dominance” refers to the artery that gives rise to the posterior interventricular artery, as seen in the anterior and posterior views. Right coronary artery and branches (green); left coronary artery and branches (red). Posterior interventricular br. A Left coronary dominance (15–17%). A A Supra-apical anterior infarction. Ascending aorta R L Right coronary a. P Circumflex br. Apical anterior infarction. B Posterior left ventricular br. Posterior interventricular br. Left coronary a. Area of deficient blood flow Posterior interventricular br. B Balanced distribution, right coronary artery dominance (67–70%). C Anterior lateral infarction. DPosterior lateral infarction. Posterior left ventricular br. Right coronary a. Posterior interventricular br. C Right coronary dominance (~15%). E Posterior infarction. 101 Thorax Conduction & Innervation of the Heart Contraction of cardiac muscle is modulated by the cardiac conduction system. This system of specialized myocardial cells (Purkinje fibers) ­generates and conducts excitatory impulses in the heart. The conduc- tion system contains two nodes, both located in the right atrium: the sinoatrial (SA) node, known as the pacemaker, and the atrioventricular (AV) node. Fig. 9.18 Cardiac conduction system Aortic arch Superior vena cava Interatrial bundle Superior vena cava Pulmonary trunk Sinoatrial (SA) node Atrioventricular (AV) bundle (of His) Sinoatrial (SA) node Anterior, middle, and posterior internodal bundles Left bundle br. Left bundle br. Right bundle br. Right atrium Right ventricle Atrioventricular (AV) node Septomarginal trabecula, (moderator band) Atrioventricular (AV) node Right bundle br. Anterior papillary m. Atrioventricular (AV) bundle Purkinje (of His) fibers Interventricular septum A Anterior view. Opened: All four chambers. Interventricular septum B Right lateral view. Opened: Right atrium and ventricle. Aortic arch Pulmonary trunk Left atrium Left bundle br. Anterior fascicle Interventricular septum Middle fascicle Posterior fascicle Left ventricle C Left lateral view. Opened: Left atrium and ventricle. Cardiac apex Subendocardial brs. Clinical box 9.4 Electrocardiogram (ECG) The cardiac impulse (a physical dipole) travels across the heart and may be detected with electrodes. The use of three electrodes that separately record electrical activity of the heart along three axes or vectors (Einthoven limb leads) generates an electrocardiogram (ECG). The ECG graphs the cardiac cycle (“heartbeat”), reducing it to a series of waves, segments, and intervals. These ECG components can be used to determine whether cardiac impulses are normal or abnormal (e.g., myocardial infarction, chamber enlargement). Note: Although only three leads are required, a standard ECG examination includes at least two others (Goldberger, Wilson leads). 102 P wave R wave T wave I Lead vectors in Einthoven’s triangle II III Recording electrodes Q wave A ECG recording electrodes. B ECG. S wave ST segment plexus. Parasympathetic innervation: Preganglionic neurons and fibers reach the heart via cardiac branches, some of which also arise in the cervical region. They synapse on postganglionic neurons near the SA node and along the coronary arteries. Fig. 9.19 Autonomic innervation of the heart Dorsal motor (vagal) nucleus Superior cervical ganglion Superior, middle, and inferior cervical cardiac nn. Vagus n. (CN X) Middle cervical ganglion T1 spinal cord segment Stellate ganglion Sympathetic trunk Sympathetic trunk, inferior cervical ganglion Superior and inferior cervical cardiac brs. Cardiac brs. to cardiac plexus Thoracic cardiac brs. Cardiac plexus 9 Mediastinum Sympathetic innervation: Preganglionic neurons from T1 to T6 spinal cord segments send fibers to synapse on postganglionic neurons in the cervical and upper thoracic sympathetic ganglia. The three cervical cardiac nerves and thoracic cardiac branches contribute to the cardiac Cervical cardiac nn. Aortic arch with thoracic aortic plexus Pulmonary a. and pulmonary vv. with pulmonary plexus Cardiac plexus Cardiac plexus (along the coronary aa.) Sinoatrial (SA) node B Autonomic plexuses of the heart, right lateral view. Note the continuity between the cardiac, aortic, and pulmonary plexuses. Atrioventricular (AV) node Myocardium Hyoid bone Sympathetic preganglionic fibers Superior laryngeal n. Sympathetic postganglionic fibers Left vagus n. Right vagus n. Parasympathetic preganglionic fibers Sympathetic trunk, middle cervical ganglion Parasympathetic postganglionic fibers A Schematic. Thyroid cartilage Thyroid gland Anterior scalene Left common carotid a. Brachial plexus Left recurrent laryngeal n. Subclavian a. Trachea Brachiocephalic trunk Thoracic aortic plexus Right recurrent laryngeal n. Left vagus n. Sympathetic trunk, thoracic ganglion Ligamentum arteriosum Right vagus n. Right phrenic n. Left phrenic n. Superior vena cava Pulmonary plexus Ascending aorta Pulmonary trunk Cardiac plexus Phrenic n. (on diaphragm) C Autonomic nerves of the heart. Anterior view of opened thorax. Fibrous Gastric plexus pericardium (opened) 103 Thorax Pre- & Postnatal Circulation Fig. 9.20 Prenatal circulation After Fritsch and Kühnel. ① Oxygenated and nutrient-rich fetal blood from the placenta passes to the fetus via the umbilical vein. ②A pproximately half of this blood bypasses the liver (via the ductus venosus) and enters the inferior vena cava. The remainder enters the portal vein to supply the liver with nutrients and oxygen. ③B lood entering the right atrium from the inferior vena cava bypasses the right ventricle (as the lungs are not yet functioning) to enter the left atrium via the oval foramen, a right-to-left shunt. ④ Blood from the superior vena cava enters the right atrium, passes to the right ventricle, and moves into the pulmonary trunk. Most of this blood enters the aorta via the ductus arteriosus, a right-to-left shunt. ⑤ The partially oxygenated blood in the aorta returns to the placenta via the paired umbilical arteries that arise from the internal iliac arteries. Aortic arch ④ Ductus arteriosus Pulmonary aa. (very little blood flow) (patent) Left pulmonary vv. (very little blood flow) Left atrium Superior vena cava ③ Oval foramen (patent) Pulmonary trunk Right atrium Left ventricle Right ventricle Hepatic vv. Liver ② Ductus venosus Anastomosis between umbilical v. and portal v. Portal v. ① Abdominal aorta Umbilical v. Inferior vena cava Umbilical aa. Common iliac a. Internal iliac a. Umbilicus ⑤ Placenta 104 Umbilical aa. Fig. 9.21 Postnatal circulation Derivatives of fetal circulatory structures Table 9.5 After Fritsch and Kühnel. Fetal structure ② The foramen ovale and ductus arteriosus close, eliminating the fetal right-to-left shunts. The pulmonary and systemic circulations in the heart are now separate. Adult remnant Ductus arteriosus Ligamentum arteriosum Foramen ovale Oval fossa (fossa ovalis) Ductus venosus Ligamentum venosum Umbilical v. Round lig. of the liver (ligamentum teres) Umbilical a. Medial umbilical lig. 9 Mediastinum ① As pulmonary respiration begins at birth, pulmonary blood pressure falls, causing blood from the right pulmonary trunk to enter the pulmonary arteries. ③ As the infant is separated from the placenta, the umbilical arteries occlude (except for the proximal portions), along with the umbilical vein and ductus venosus. ④ Blood to be metabolized now passes through the liver. Aortic arch ② Ligamentum arteriosum (obliterated ductus arteriosus) ① Pulmonary aa. (perfused) Left pulmonary vv. (perfused) Left atrium Superior vena cava ② Oval foramen (closed) Pulmonary trunk Left ventricle Right atrium Right ventricle Hepatic vv. Liver ④ Ligamentum venosum (obliterated ductus venosus) Clinical box 9.5 Septal defects Portal v. Round lig. of liver (obliterated umbilical v.) Abdominal aorta ③ Inferior vena cava Umbilical cord Septal defects, the most common type of congenital heart defect, allow blood from the left chambers of the heart to improperly pass into the right chambers during systole. Ventricular septal defect (VSD, shown below) is a defect in either the membranous or muscular portion of the ventricular septum—most commonly the membranous portion. Patent foramen ovale, the most prevalent form of atrial septal defect (ASD), results from improper closure of the fetal shunt. LV, left ventricle; RV, right ventricle. Umbilicus Obliterated umbilical aa. (medial umbilical ligs.) LV RV 105 Thorax Esophagus The esophagus is divided into three parts: cervical (C6–T1), thoracic (T1 to the esophageal hiatus of the diaphragm), and abdominal (the diaphragm to the cardiac orifice of the stomach). It descends slightly to the right of the thoracic aorta and pierces the diaphragm slightly to the left, just below the xiphoid process of the sternum. C6 Fig. 9.22 Esophagus: Location and constrictions Cricoid cartilage Upper esophageal (pharyngoesophageal) constriction Esophageal inlet Cervical part Trachea, thoracic part Sternum T4 Thoracic part Middle esophageal (thoracic) constriction Diaphragm Abdominal part Diaphragm T10 A Projection of esophagus onto chest wall. Esophageal constrictions are indicated with arrows. Lower esophageal (phrenic) constriction Aorta B Esophageal constrictions, right lateral view. Fig. 9.23 Esophagus in situ Anterior view. Trachea, cervical part Esophagus, cervical part Left internal jugular v. Brachial plexus Left subclavian a. and v. Anterior scalene Brachiocephalic trunk Left brachiocephalic v. Right brachiocephalic v. Parietal pleura, cervical part Aortic arch Ligamentum arteriosum Azygos v., arch Left pulmonary a. Left vagus n. Right pulmonary a. Superior and inferior lobar bronchi Right pulmonary vv. Right vagus n. Thoracic aorta Pulmonary trunk Parietal pleura, mediastinal part Azygos v. Thoracic duct Anterior esophageal plexus Parietal pleura, diaphragmatic part 106 Esophagus, thoracic part Central tendon Stomach of diaphragm Mucosa, longitudinal folds Mediastinal part Muscularis Diaphragmatic part Parietal pleura Longitudinal layer Esophageal hiatus Pharyngeal raphe Thyroid cartilage Gastroesophageal junction (Z line) Inferior pharyngeal constrictor, thyropharyngeal part Killian’s triangle Inferior pharyngeal constrictor, cricopharyngeal part Cricoid cartilage Parietal peritoneum Peritoneal cavity Muscular coat, circular layer Trachea Esophagus Gastric fundus Visceral peritoneum 9 Mediastinum Fig. 9.24 Structure of the esophagus Circular layer Gastric cardia Gastric folds (rugae) Esophagogastric junction, anterior view. A true sphincter is not B identifiable at this junction; instead, the diaphragmatic muscle of the esophageal hiatus functions as a sphincter. It is often referred to as the “Z line” because of its zigzag form. Muscular coat, longitudinal layer Muscular coat, circular layer Submucosa Mucosa A Esophageal wall, oblique left posterior view. Pharynx (p. 650); trachea (p. 120). Functional architecture of esophageal muscle. C Clinical box 9.6 Esophageal diverticula Inferior pharyngeal constrictor Zenker’s diverticulum • Hypopharyngeal (pharyngo-esophageal) diverticula: Outpouchings ­occurring at the junction of the pharynx and the esophagus. These include Zenker’s diverticula (70% of cases). Trachea Parabronchial diverticulum Left main bronchus Diverticula (abnormal outpouchings or sacs) generally develop at weak spots in the esophageal wall. There are three main types of esophageal diverticula: Right main bronchus Esophagus (thoracic part) Epiphrenic diverticulum Diaphragm • “True” traction diverticula: Protrusion of all wall layers, not typically ­occurring at characteristic weak spots. However, they generally result from an inflammatory process (e.g., lymphangitis) and are thus common at sites where the esophagus closely approaches the bronchi and bronchial lymph nodes (thoracic or parabronchial diverticula). • “False” pulsion diverticula: Herniations of the mucosa and submucosa through weak spots in the muscular coat due to a rise in esophageal pressure (e.g., during normal swallowing). These include parahiatal and epiphrenic diverticula occurring above the esophageal aperture of the diaphragm (10% of cases). Esophagus, abdominal part 107 Thorax Neurovasculature of the Esophagus Sympathetic innervation: Preganglionic fibers arise from the T2–T6 spinal cord segments. Postganglionic fibers arise from the sympathetic trunk to join the esophageal plexus. Parasympathetic innervation: ­Preganglionic fibers arise from the dorsal vagal nucleus and travel in Fig. 9.25 Autonomic innervation of the esophagus the vagus nerves to form the extensive esophageal plexus. Note: The postganglionic neurons are in the wall of the esophagus. Fibers to the cervical portion of the esophagus travel in the recurrent laryngeal nerves. Vagus n. (CN X) Dorsal motor (vagal) nucleus Esophagus, cervical part Sympathetic trunk Esophageal brs. T2 spinal cord segment Recurrent laryngeal n. Esophagus, thoracic part Esophageal plexus T6 spinal cord segment Vagal trunk Esophagus, abdominal part Sympathetic preganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Fig. 9.26 Esophageal plexus Trachea The left and right vagus nerves initially descend on the left and right sides of the esophagus. As they begin to contribute to the esophageal plexus, they shift to anterior and posterior positions, respectively. As the vagus nerves continue into the abdomen, they are named the anterior and posterior vagal trunks. Sympathetic trunk, middle cervical ganglion Right subclavian a. Right recurrent laryngeal n. Right vagus n. Brachiocephalic trunk Right recurrent laryngeal n. Left recurrent laryngeal n. Right vagus n. Left vagus n. 3rd through 6th thoracic ganglia Esophageal brs. Esophageal plexus Left sympathetic trunk Right sympathetic trunk Stomach Anterior vagal trunk 108 Left common carotid a. Brachial plexus Left subclavian a. First rib Left vagus n. Posterior intercostal a. Left recurrent laryngeal n. Intercostal n. Aortic arch Right main bronchus Esophagus, thoracic part Sympathetic trunk Anterior vagal trunk with esophageal plexus Left main bronchus Thoracic aorta Sympathetic trunk Greater splanchnic n. Caval opening Anterior gastric plexus A Anterior view. Note the postganglionic sympathetic contribution to the ­esophageal plexus. Esophagus, cervical part Diaphragm Anterior gastric plexus Stomach B Esophageal plexus in situ. Anterior view. Fig. 9.27 Esophageal arteries Left vagus n. Anterior view. Esophageal plexus Inferior thyroid a. Right common carotid a. Left common carotid a. Thyrocervical trunk Posterior vagal trunk Esophageal brs. Left subclavian a. Internal thoracic a. Brachiocephalic trunk Trachea Stomach Anterior scalene 9 Mediastinum Right vagus n. Vertebral a. Aortic arch Posterior gastric plexus Left main bronchus C Posterior view. Posterior intercostal aa. Esophageal brs. (from thoracic aorta) Thoracic aorta Diaphragm Gastric fundus Esophageal br. Left inferior phrenic a. Fig. 9.28 Esophageal veins Anterior view. Anterior scalene Left gastric a. Celiac trunk Inferior thyroid v. Left internal jugular v. Common hepatic a. Splenic a. Abdominal aorta Esophageal vv. Left external jugular v. Right brachiocephalic v. Superior vena cava Left subclavian v. Left brachiocephalic v. Accessory hemiazygos v. Esophageal vv. Azygos v. Posterior intercostal vv. Table 9.6 Origin of esophageal arteries Drainage of esophageal veins Diaphragm Inferior thyroid a. Inferior thyroid v. Esophageal vv. Rarely direct brs. from thyrocervical trunk or common carotid a. Left brachiocephalic v. Hemiazygos v. Part Cervical Left gastric v. Blood vessels of the esophagus Thoracic Aorta (four or five esophageal aa.) Upper left: Accessory hemiazygos v. or left brachiocephalic v. Lower left: Hemiazygos v. Right side: Azygos v. Abdominal Left gastric a. Left gastric v. 109 Thorax Lymphatics of the Mediastinum The superior phrenic lymph nodes drain lymph from the diaphragm, pericardium, lower esophagus, lung, and liver into the broncho­ mediastinal trunk. The inferior phrenic lymph nodes, found in the a­ bdomen, collect lymph from the diaphragm and lower lobes of the lung and convey it to the lumbar trunk. Note: The pericardium may also drain superiorly to the brachiocephalic lymph nodes. Esophagus Fig. 9.29 Lymph nodes of the mediastinum and thoracic cavity Trachea Left jugular trunk Left anterior oblique view. Thoracic duct at junction of left subclavian and internal jugular veins Right brachiocephalic vein Left brachiocephalic vein Brachiocephalic l.n. Paratracheal l.n. Superior vena cava Thoracic duct Tracheobronchial l.n. Intercostal lymphatics Prevertebral l.n. Fibrous pericardium Superior phrenic l.n. Diaphragm Celiac l.n. Celiac trunk Abdominal aorta Stomach Fig. 9.30 Lymphatic drainage of the heart Trachea A unique “crossed” drainage pattern exists in the heart: lymph from the left atrium and ventricle drains to the right venous junction, whereas lymph from the right atrium and ventricle drains to the left venous junction. Junction of right subclavian and internal jugular vv. Superior vena cava Superior vena cava Left ventricle Trachea Aortic arch Right coronary trunk Left ventricle Trachea Inferior tracheobronchial l.n. Bronchopulmonary l.n. Left atrium Left coronary trunk C Posterior view. 110 Right ventricle B Lymphatic drainage of the right chambers, anterior view. Left coronary trunk A Lymphatic drainage of the left chambers, anterior view. Aortic arch Bronchopulmonary l.n. Inferior tracheobronchial l.n. Right ventricle Junction of left subclavian and internal jugular vv. Superior vena cava Bronchopulmonary l.n. Right atrium Right coronary trunk the upper half drains cranially, and the lower half drains inferiorly via the superior phrenic lymph nodes. The bronchopulmonary and paratracheal nodes drain lymph from the lungs, bronchi, and trachea into the bronchomediastinal trunk (see p. 128). Fig. 9.31 Mediastinal lymph nodes Paraesophageal l.n. Esophagus 9 Mediastinum The paraesophageal nodes drain the esophagus. Lymphatic drainage of the cervical part of the esophagus is primarily cranial, to the deep cervical lymph nodes and then to the jugular trunk. The thoracic part of the esophagus drains to the bronchomediastinal trunks in two parts: Trachea Paratracheal l.n. Right main bronchus Left main bronchus Inferior tracheobronchial l.n. Paraesophageal l.n. Diaphragm Inferior phrenic l.n. Cardiac lymphatic ring (inconstant) Stomach Left internal jugular v. A Anterior view of opened thorax. Left common carotid a. Esophagus Trachea Left subclavian a. and v. Paraesophageal l.n. Superior vena cava Bronchopulmonary l.n. Aortic arch Azygos v. Left pulmonary a. Left main bronchus Tracheobronchial l.n. Bronchopulmonary l.n. Paraesophageal l.n. Fibrous pericardium Inferior vena cava Diaphragm B Posterior view of mediastinal lymph nodes. 111 10 Pulmonary Cavities Thorax Pulmonary Cavities The paired pulmonary cavities contain the left and right lungs. They are completely separated from each other by the media­stinum and are under negative atmospheric pressure (see respiratory mechanics, pp. 122–123). The left pulmonary cavity is slightly smaller than the right, especially anteriorly, due to the asymmetrical position of the heart in the mediastinum, with the greater mass on the left. This causes a shift of some of the boun­daries of the parietal pleura and lung on the left side at the level of the heart, as reflected in the difference in thoracic landmarks found at the intersection of the anterior border of the pulmonary cavities with certain reference lines on the left and right. Fig. 10.1 Boundaries of the lungs and pulmonary cavities The upper red dot on each reference line is the inferior boundary of the lung and the lower blue dot is the inferior boundary of the pulmonary cavity. Midclavicular Sternal line line A Anterior view. B Posterior view. Paravertebral line Scapular line Parietal pleura Parietal pleura Midaxillary line Midaxillary line Costodiaphragmatic recess of pulmonary cavity Costodiaphragmatic recess of pulmonary cavity C Right lateral view. Table 10.1 112 DLeft lateral view. Pulmonary cavity boundaries and reference points Reference line Right lung Right parietal pleura Left lung Left parietal pleura Sternal line (STL) 6 rib 7 rib 4 rib 4th rib Midclavicular line (MCL) 6th rib 8th costal cartilage 6th rib 8th rib Midaxillary line (MAL) 8 rib 10 rib 8 rib 10th rib Scapular line (SL) 10 rib 11 rib 10 rib 11th rib Paravertebral line (PV) 10th rib T12 vertebra 10th rib T12 vertebra th th th th th th th th th Fig. 10.2 Parietal pleura The pulmonary cavity is bounded by two serous layers. The visceral pleura covering the lungs, and parietal pleura lining the inner surfaces of the thoracic cavity. The four divisions of the parietal pleura (costal, diaphragmatic, mediastinal, and cervical) are continuous. Cervical part Visceral pleura Parietal pleura, diaphragmatic part Intercostal v., a., and n. Diaphragm Parietal pleura, costal part Costal part Parietal peritoneum 10 Pulmonary Cavities Right lung 8th rib Visceral peritoneum Mediastinal part Diaphragmatic part Pericardial sac A Parts of the parietal pleura. Opened: Right pleural cavity, anterior view. Costodiaphragmatic recess Costal groove Endothoracic fascia External intercostal Liver Innermost intercostal Internal intercostal B Costodiaphragmatic recess, coronal section, anterior view. Reflection of the diaphragmatic pleura onto the inner ­thoracic wall (becoming the costal pleura) forms the costodiaphragmatic recess. Costomediastinal recess Fibrous Serous pericardium pericardium Parietal pleura, mediastinal part Left lung, superior lobe Right lung, superior lobe Horizontal fissure Right lung, middle lobe Parietal pleura, costal part Visceral pleura Oblique fissure Oblique fissure Left main broncus Right lung, inferior lobe Left lung, inferior lobe Phrenic n. C Transverse section at T7, inferior view. Reflection of the costal pleura onto the pericardium forms the costomediastinal recess. Right Sympathetic Spinal Azygos v., Hemiazygos v. cord thoracic duct, trunk main bronchus and left vagus n. Parietal pleura, costal part Thoracic aorta 113 Thorax Pleura: Subdivisions, Recesses & Innervation Fig. 10.3 Pleura and its divisions The anterior thoracic wall and costal portion of the parietal pleura have been removed to show the lungs in situ. Parietal pleura, mediastinal part Superior lobe Parietal pleura, costal part Internal thoracic a. and v. Lung with visceral pleura Middle lobe Fibrous pericardium Inferior lobe Parietal pleura, mediastinal part Parietal pleura, diaphragmatic part Fig. 10.4 Innervation of the pleura The costal and cervical portions and the periphery of the diaphragmatic portion of the parietal pleura are innervated by the intercostal nerves. The mediastinal and central portions of the diaphragmatic pleura are innervated by the phrenic nerves. The visceral pleura covering the lung itself receives its innervation from the autonomic nervous system. Parietal pleura innervated by intercostal nn. Parietal pleura innervated by phrenic n. Visceral pleura innervated by autonomic nn. 114 Fig. 10.5 Costomediastinal and costodiaphragmatic recesses Parietal pleura, mediastinal part Costomediastinal recess Pericardiacophrenic a. and v., phrenic n. Internal thoracic a. and v. 10 Pulmonary Cavities On the left side of the thorax, an examiner’s fingertips are placed in the costomediastinal and costodiaphragmatic recesses. These recesses are formed by the acute reflection of the costal part of the parietal pleura onto the fibrous pericardium as mediastinal pleura (costomediastinal) or on to the diaphragm as diaphragmatic pleura (costodiaphragmatic). Parietal pleura, costal pleura Fibrous pericardium Costodiaphragmatic recess Fig. 10.6 Pleural recesses Transverse section at T8, superior view. Costomediastinal recess Fibrous pericardium Anterior mediastinum Sternum, body Costomediastinal recess Internal thoracic a. and v. Serous pericardium, parietal layer Parietal pleura, diaphragmatic part Phrenic n., pericardiacophrenic a. and v. Parietal pleura, costal part Diaphragm, costal part Phrenic n., pericardiacophrenic a.and v. Costodiaphragmatic recess Inferior vena cava Diaphragm, central tendon Esophagus Parietal pleura, mediastinal part Thoracic duct Hemiazygos v. Azygos v. Costodiaphragmatic recess Left sympathetic trunk Thoracic aorta Right sympathetic trunk 115 Thorax Lungs Fig. 10.7 Lungs in situ Mediastinum The left and right lungs occupy the full volume of the pleural cavity. Note that the left lung is slightly smaller than the right due to the asymmetrical position of the heart. Superior lobe Superior lobe Horizontal fissure Right lung Middle lobe Oblique fissure Oblique fissure Left lung Inferior lobe Inferior lobe A Topographical relations of the lungs, transverse section, inferior view. Esophagus Descending aorta Left subclavian a. and v. Brachiocephalic trunk Left brachiocephalic v. Parietal pleura, cervical part Aortic arch Pulmonary apex Right lung, superior lobe Superior vena cava Left pulmonary a. Right pulmonary a. Superior and inferior lobar bronchi Right pulmonary vv. Left lung, superior lobe Right lung, horizontal fissure Thoracic aorta Pulmonary trunk Right lung, middle lobe Parietal pleura, mediastinal part Left lung, oblique fissure Right lung, oblique fissure Parietal pleura, costal part Right lung, inferior lobe Left lung, inferior lobe Costodiaphragmatic recess Diaphragm B Anterior view with lungs retracted. 116 Parietal pleura, diaphragmatic part Esophagus, thoracic part Central tendon of diaphragm Parietal layer of serous pericardium Fibrous pericardium Fig. 10.8 Gross anatomy of the lungs extends into the root of the neck. The hilum is the location at which the bronchi and neurovascular structures connect to the lung. Apex 10 Pulmonary Cavities The oblique and horizontal fissures divide the right lung into three lobes: superior, middle, and inferior. The oblique fissure divides the left lung into two lobes: superior and inferior. The apex of each lung Apex Superior lobe Superior lobe Anterior border (inserts into costomediastinal recess) Costal surface Oblique fissure Anterior border (inserts into costomediastinal recess) Horizontal fissure Middle lobe Costal surface Inferior lobe Inferior lobe Lingula Oblique fissure Inferior border (inserts into costodiaphragmatic recess) Inferior border (inserts into costodiaphragmatic recess) A Right lung, lateral view. B Left lung, lateral view. Apex Branches of right pulmonary a. Mediastinal surface Anterior border Hilum Horizontal fissure Apex Superior lobe Superior lobar bronchus Inferior and middle lobar bronchi (common origin) Branches of right pulmonary vv. Middle lobe Diaphragmatic surface (base of lung) C Right lung, medial view. Costal surface, vertebral part Pulmonary lig. Branches of left pulmonary a. Oblique fissure Superior and inferior lobar bronchi Hilum Branches of left pulmonary vv. Aortic impression Cardiac impression Inferior lobe Cardiac notch Costal surface (vertebral part) Inferior border (inserts into costodiaphragmatic recess) Inferior border (inserts into costodiaphragmatic recess) Mediastinal surface Anterior border Oblique fissure Inferior lobe Cardiac impression Superior lobe Lingula Pulmonary lig. Diaphragmatic surface (base of lung) DLeft lung, medial view. 117 Thorax Bronchopulmonary Segments of the Lungs (segmental) bronchus. Note: These subdivisions are not defined by surface boundaries but by origin. The lung lobes are subdivided into bronchopulmonary segments, the smallest resectable portion of a lung, each supplied by a tertiary Fig. 10.9 Segmentation of the lung Anterior view. See pp. 120–121 for details of the trachea and bronchial tree. Trachea and bronchial tree Right lung Left lung Right lung Left lung I I II II I I I II I II II III II III III III Horizontal fissure IV IV IV IV VI V VIII X VIII Oblique fissure Oblique V VII fissure IX V IV V Oblique fissure III III Horizontal fissure X IV VI VII, VIII V Oblique fissure V IX VII, VIII VIII VII, VIII Fig. 10.10 Anteroposterior bronchogram Anterior view of right lung. Table 10.2 Segmental architecture of the lungs Each segment is supplied by a segmental bronchus of the same name (e.g., the apical segmental bronchus supplies the apical segment). See pp. 120–121 for details of the trachea and bronchial tree. Right lung Left lung Superior lobe I Apical segment II Posterior segment III Apicoposterior segment Anterior segment Middle lobe I II III Lingula IV Lateral segment Superior lingular segment IV V Medial segment Inferior lingular segment V Inferior lobe 118 VI Superior segment VI VII Medial basal segment VII VIII Anterior basal segment VIII IX Lateral basal segment IX X Posterior basal segment X Fig. 10.11 Right lung: Bronchopulmonary segments I II II II III III VI VI Horizontal fissure V VI X Oblique fissure IV VIII VII IX X VIII X IX A Medial view. B Posterior view. V VIII 10 Pulmonary Cavities I I IX C Lateral view. Fig. 10.12 Left lung: Bronchopulmonary segments I I I II II Oblique fissure II III III IV III VI VI VI IV IV VII, VIII V X IX V X VII, VIII IX A Medial view. VII, VIII B Posterior view. IX X C Lateral view. Clinical box 10.1 Lung resections Lung cancer, emphysema, or tuberculosis may necessitate the surgical removal of damaged portions of the lung. Surgeons exploit the anatomical subdivision of the lungs into lobes and segments when excising damaged tissue. Trachea Segment I of right lung Right lung Superior lobe of right lung Left lung A Segmentectomy (wedge resection): Removal of one or more segments. B Lobectomy: Removal of lobe. C Pneumonectomy: Removal of entire lung. 119 Thorax Trachea & Bronchial Tree At or near the level of the sternal angle (T4/T5), the lowest tracheal cartilage extends anteroposteriorly, forming the carina. The trachea bifurcates at the carina into the right and left main bronchi. Each bronchus gives off lobar branches to the corresponding lung. Fig. 10.13 Trachea See p. 530 for the structures of the thyroid. Cervical part Tracheal bifurcation Thoracic part Right main bronchus Trachea Left main bronchus Thyroid cartilage Median cricothyroid lig. Cricoid cartilage A Projection of trachea onto chest. Tracheal cartilages Thyroid cartilage Anular ligs. Arytenoid cartilage Right main bronchus Cricoid cartilage Membranous posterior wall (with tracheal glands) Tracheal cartilages Left main bronchus I Right superior lobar bronchus Position of carina (at tracheal bifurcation) Right middle lobar bronchus Right main bronchus IV X II III IV Left main bronchus VIII VII IX X V Tracheal bifurcation Right/left inferior lobar bronchi Left superior lobar bronchus VI VIII X VII IX IX B Anterior view. Clinical box 10.2 IV VI Foreign body aspiration V VIII VII IX Posterior view with opened posterior wall. C 120 V VII III VI VI VIII I V III III IV I II II Mucosa II I X Toddlers are at particularly high risk of potentially fatal aspiration of foreign bodies. In general, foreign bodies are more likely to become lodged in the right main bronchus than the left: the left bronchus diverges more sharply at the tracheal bifurcation to pass more horizontally over the heart, whereas the right bronchus is relatively straight and more in line with the trachea. The conducting portion of the bronchial tree extends from the tracheal bifurcation to the terminal bronchiole, inclusive. The respiratory portion consists of the respiratory bronchiole, alveolar ducts, alveolar sacs, and alveoli. 10 Pulmonary Cavities Fig. 10.14 Bronchial tree Smooth muscle (lattice arrangement) Segmental bronchus Cartilaginous plate Elastic fibers Pulmonary alveolus Large subsegmental bronchus Respiratory bronchioles Conduction portion of airway Small subsegmental bronchus Interalveolar septum Alveolar duct Alveolar sac Alveolus Respiratory bronchiole Respiratory portion of airway Pulmonary alveoli Bronchiole (cartilage-free wall) Terminal bronchiole Acinus B Respiratory portion of the bronchial tree. see B Alveolar sacs Clinical box 10.3 A Divisions of the bronchial tree. Respiratory compromise The most common cause of respiratory compromise at the bronchial level is asthma. Compromise at the alveolar level may result from increased diffusion distance, decreased aeration (emphysema), or fluid infiltration (e.g., pneumonia). Capillary Capillary Type II Surfactant endothelial cell lumen pneumocyte Alveolar lumen Erythrocyte Diffusion distance: Gaseous exchange takes place between the alveolar and capillary lumens in the alveoli (see Fig. 10.14C). At these sites, the basement membranes of capillary endothelial cells are fused with those of type I alveolar epithelial cells, lowering the exchange distance to 0.5 µm. Diseases that increase this diffusion distance (e.g., edematous fluid collection or inflammation) result in compromised respiration. Condition of alveoli: In diseases like emphysema, which occurs in chronic obstructive pulmonary disease (COPD), alveoli are destroyed or damaged. This reduces the surface area available for gaseous exchange. Alveolar macrophage Type I pneumocyte Elastic fibers in the interalveolar septum Fusion of the basement membranes Production of surfactant: Surfactant is a protein-phospholipid film that lowers the surface tension of the alveoli, making it easier for the lung to expand. The immature lungs of a preterm infant often fail to produce sufficient surfactant, leading to respiratory problems. Surfactant is produced and absorbed by alveolar epithelial cells (pneumocytes). Type I alveolar epithelial cells absorb surfactant; type II produce and release it. Epithelial lining of the alveoli. C 121 Thorax Respiratory Mechanics The mechanics of respiration are based on a rhythmic increase and decrease in thoracic volume, with an associated expansion and contraction of the lungs. Inspiration (red): Contraction of the diaphragm leaflets lowers the diaphragm into the inspiratory position, increasing the volume of the pleural cavity along the vertical axis. Contraction of the thoracic muscles (external intercostals with the scalene, intercartilaginous, and posterior serratus muscles) elevates the ribs, expanding the pleural cavity along the sagittal and transverse axes (Fig. 10.16A,B). Surface tension in the pleural space causes the visceral and parietal pleura to adhere; thus, changes in thoracic volume alter the volume of the lungs. This is particularly evident in the pleural recesses: at functional residual capacity (resting position between inspiration and expiration), the lung does not fully occupy the pleural cavity. As the pleural cavity expands, a negative intrapleural pressure is generated. The air pressure differential results in an influx of air (inspiration). Expiration (blue): During passive expiration, the muscles of the thoracic cage relax and the diaphragm returns to its expiratory position. Contraction of the lungs increases the pulmonary pressure and expels air from the lungs. For forcible expiration, the internal intercostal muscles (with the transverse thoracic and subcostal mucosa) can actively lower the rib cage more rapidly and to a greater extent than through passive elastic recoil. Fig. 10.15 Respiratory changes in thoracic volume 1st rib Inspiratory position (red); expiratory position (blue). Sternum Expiratory position Diaphragm Inspiratory position Fig. 10.16 Inspiration: Pleural cavity expansion T12 vertebra Expansion (vertical axis) Inspiration 1st rib Thoracic inlet Fig. 10.18 Respiratory changes in lung volume Diaphragm Expansion (transverse axis) Expansion (sagittal axis) A Anterior view. B Left lateral view. Epigastric angle Inferior border of lung (full expiration) C Anterolateral view. Fig. 10.17 Expiration: Pleural cavity contraction Contraction (vertical axis) Expiration Contraction (transverse axis) A Anterior view. 122 Contraction (sagittal axis) B Left lateral view. C Anterolateral view. Inferior border of lung (full inspiration) Fig. 10.19 Inspiration: Lung expansion Fig. 10.20 Expiration: Lung contraction Right lung (full expiration) Pleural space As the volume of the lung changes with the volume of the thoracic cavity, the entire bronchial tree moves within the lung. These structural movements are more pronounced in portions of the bronchial tree distant from the pulmonary hilum. Trachea Diaphragm Lung (full expiration) 10 Pulmonary Cavities Right lung (full inspiration) Fig. 10.21 Movements of the lung and bronchial tree Diaphragm Costodiaphragmatic recess Costodiaphragmatic recess Lung (full inspiration) Clinical box 10.4 Pneumothorax The pleural space is normally sealed from the outside environment. Injury to the parietal pleura, visceral pleura, or lung allows air to enter the pleural cavity (pneumothorax). The lung collapses due to its inherent elasticity, and the patient’s ability to breathe is compromised. The uninjured lung continues to function under normal pressure variations, resulting in “mediastinal flutter”: the mediastinum shifts toward the normal side during inspiration and returns to the midline during expiration. Tension (valve) pneumothorax occurs when traumatically detached and displaced tissue covers the defect in the thoracic wall from the inside. This mobile flap allows air to enter, but not escape, the pleural cavity, causing a pressure buildup. The mediastinum shifts to the normal side, which may cause kinking of the great vessels and prevent the return of venous blood to the heart. Without treatment, tension pneumothorax is invariably fatal. Airflow into pleural defect Normal airflow during inspiration Right lung Left lung Collapsed lung Inspiration Cardiac shift Positive pressure in pleural cavity Normal airflow during expiration Airflow out of pleural defect Expiration Cardiac shift A Normal respiration. Pleural defect during inspiration B Pneumothorax. “Empty” pleural cavity at atmospheric pressure Collapsed lung One-way “valve” Cardiac shift C Tension pneumothorax. 123 Thorax Pulmonary Arteries & Veins The pulmonary trunk arises from the right ventricle and divides into a left and right pulmonary artery for each lung. The paired pulmonary veins open into the left atrium on each side. The pulmonary arteries accompany and follow the branching of the bronchial tree, whereas the pulmonary veins do not, being located at the margins of the pulmonary lobules. Fig. 10.22 Pulmonary arteries and veins Anterior view. Right pulmonary a. Right internal jugular v. Left pulmonary a. Pulmonary trunk Left internal jugular v. Right subclavian v. Left subclavian v. Right brachiocephalic v. Left brachiocephalic v. Superior vena cava Left pulmonary vv. Right pulmonary vv. Inferior vena cava A Projection of pulmonary arteries on chest wall. B Projection of pulmonary veins on chest wall. Trachea Left lung Right lung Superior lobe Superior lobe Aortic arch Right main bronchus Left main bronchus Right pulmonary a. Left pulmonary a. Superior right pulmonary v. Superior left pulmonary v. Inferior right pulmonary v. Inferior left pulmonary v. Superior vena cava Ascending aorta Pulmonary trunk Right atrium Left ventricle Middle lobe Inferior lobe Inferior vena cava C Distribution of the pulmonary arteries and veins, anterior view. 124 Right ventricle Cardiac apex Inferior lobe Fig. 10.23 Pulmonary arteries Fig. 10.24 Pulmonary veins Left common carotid a. Left subclavian a. S Aortic arch Right pulmonary a. ②① ⑪ ⑫ ③ Middle lobe a. ⑬ ⑥ ④ ⑮ ⑤ A Schematic. Table 10.3 ⑩ ⑦ ⑧⑨ Pulmonary trunk ⑭ ⑲⑱ Ligamentum arteriosum Left pulmonary a. ⑯ F Right/left superior pulmonary v. G L Right/left inferior pulmonary v. K J ⑰ Table 10.4 Left pulmonary artery ⑪ ② Posterior segmental a. ⑫ ① Apical v. ③ Anterior segmental a. ⑬ ② Posterior v. ③ Middle lobe arteries ⑤ Medial segmental a. ⑥ Superior segmental a. ⑮ ⑦ Anterior basal segmental a. ⑯ ⑧ Lateral basal segmental a. ⑰ ⑨ Posterior basal segmental a. ⑱ ⑩ Medial basal segmental a. ⑲ B Pulmonary arteriogram, arterial phase, anterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Left pulmonary vein Apicoposterior v. ⑩ Anterior v. Anterior v. ⑪ ④ Middle lobe v. Lingular v. ⑫ ⑤ Superior v. ⑬ ⑥ Common basal v. ⑭ ⑦ Inferior basal v. ⑮ ⑧ Superior basal v. ⑯ ⑨ Anterior basal v. ⑰ ⑭ Inferior lobe arteries N Superior pulmonary veins Apical segmental a. Lingular a. V Pulmonary veins and their tributaries ① Lateral segmental a. X CB H Right pulmonary vein Superior lobe arteries ④ Ö Ä Y A Schematic. Pulmonary arteries and their branches Right pulmonary artery D A 10 Pulmonary Cavities Brachiocephalic trunk Inferior pulmonary veins B Pulmonary arteriogram, venous phase, anterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Clinical box 10.5 Pulmonary embolism Potentially life-threatening pulmonary embolism occurs when blood clots migrate through the venous system and become lodged in one of the arteries supplying the lungs. Symptoms include dyspnea (difficulty breathing) and tachycardia (increased heart rate). Most pulmonary emboli originate from stagnant blood in the veins of the lower limb and pelvis (venous thromboemboli). Causes include immobilization, disordered blood coagulation, and trauma. Note: A thromboembolus is a thrombus (blood clot) that has migrated (embolized). 125 Thorax Neurovasculature of the Tracheobronchial Tree Fig. 10.25 Pulmonary vasculature Bronchial a. The pulmonary system is responsible for gaseous exchange within the lung. Pulmonary arteries (shown in blue) carry deoxygenated blood and follow the bronchial tree. The pulmonary vein and its tributaries (red) is the only vein in the body carrying oxygenated blood, which it receives from the alveolar capillaries at the periphery of the lobule. Smooth muscle Br. of pulmonary a. (deoxygenated blood) Respiratory bronchiole Tributary of pulmonary v. (oxygenated blood) Capillary bed on an alveolus Pulmonary alveolus Fibrous septum between pulmonary lobules Pulmonary alveolus Subpleural connective tissue Fig. 10.26 Arteries of the tracheobronchial tree The bronchial tree receives its nutrients via the bronchial arteries, found in the adventitia of the airways. Typically, there are one to three bronchial arteries arising directly from the aorta. Origin from a posterior intercostal artery may also occur. Trachea Brachiocephalic trunk Ascending aorta Posterior intercostal a. Left subclavian a. Left common carotid a. Aortic arch Bronchial brs. (from the thoracic aorta) Right main bronchus Left main bronchus Superior lobe bronchus Bronchial brs. (from a posterior intercostal a.) Superior lobe bronchus Inferior lobe bronchus Middle lobe bronchus Posterior intercostal aa. Inferior lobe bronchus Thoracic aorta 126 Fig. 10.27 Veins of the tracheobronchial tree Trachea Right brachiocephalic v. Accessory hemiazygos v. Left main bronchus Superior vena cava Bronchial vv. (opening into the accessory hemiazygos v.) Superior lobe bronchus 10 Pulmonary Cavities Left brachiocephalic v. Inferior thyroid v. Superior lobe bronchus Bronchial vv. (opening into the azygos v.) Middle lobe bronchus Inferior lobe bronchus Inferior lobe bronchus Azygos v. Fig. 10.28 Autonomic innervation of the tracheobronchial tree Sympathetic innervation (red); parasympathetic innervation (blue). Hemiazygos v. Vagus n. (CN X) Dorsal motor (vagal) nucleus Middle cervical ganglion Postganglionic fibers (to cardiac plexus ) Larynx, thyroid cartilage Superior laryngeal n. Cervicothoracic (stellate) ganglion Recurrent laryngeal n. T1 spinal cord segment Laryngopharygeal brs. 2nd - 5th thoracic sympathetic ganglia Autonomic brs. to trachea Pulmonary plexus Greater splanchnic (to abdomen) Trachea Bronchial brs. in pulmonary plexus Sympathetic preganglionic fibers Sympathetic postganglionic fibers Right main bronchus Left main bronchus Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers 127 Thorax Lymphatics of the Pleural Cavity The lungs and bronchi are drained by two lymphatic drainage systems. The peribronchial network follows the bronchial tree, draining lymph from the bronchi and most of the lungs. The subpleural network collects lymph from the peripheral lung and visceral pleura. Fig. 10.29 Lymphatic drainage of the pleural cavity and thoracic wall Trachea To right bronchomediastinal trunk To left bronchomediastinal trunk Right lung Left lung A Peribronchial network, coronal section, anParatracheal l.n. terior view. (Intra)pulmonary nodes along Superior tracheothe bronchial tree drain lymph from the bronchial l.n. lungs into the bronchopulmonary (hilar) nodes. Lymph then passes sequentially To inferior through the inferior and superior tracheo- tracheobronchial l.n. bronchial nodes, paratracheal nodes, bronchomediastinal trunk, and finally to the right lymphatic or thoracic duct. Note: Significant amounts of lymph from the left lower lobe drain to the right supeDiaphragm rior tracheobronchial nodes. Inferior tracheobronchial l.n. Drainage through diaphragm Inferior phrenic l.n. Parasternal l.n. Sternum Bronchopulmonary l.n. Intrapulmonary l.n. Tracheobronchial l.n. Paratracheal l.n. Lymphatics in the trunk wall Peribronchial network B Subpleural and thoracic wall networks, transverse section, superior view. 128 Subpleural network Trachea Intercostal l.n. 10 Pulmonary Cavities Fig. 10.30 Lymph nodes of the pleural cavity Anterior view of pulmonary nodes. Right internal jugular v. Right jugular trunk Right subclavian v. Left jugular trunk Trachea Deep cervical l.n. Thoracic duct Right subclavian trunk Right bronchomediastinal trunk Left subclavian trunk Left bronchomediastinal trunk Paratracheal l.n. Superior tracheobronchial l.n. Right main bronchus Inferior tracheobronchial l.n. Left main bronchus Bronchopulmonary l.n. Intrapulmonary l.n. Thoracic aorta Right lung Left lung Clinical box 10.6 Carcinoma of the Lung Carcinoma of the lung accounts for ≈ 20% of all cancers and is mainly caused by cigarette smoking. It arises first in the lining of the bronchi and metastasizes quickly to bronchopulmonary lymph nodes and subsequently to other node groups, including supraclavicular nodes. It can also spread via the blood to the lungs, brain, bone, and suprarenal glands. Lung cancer can invade adjacent structures such as the phrenic nerve, resulting in paralysis of a hemidiaphragm, or the recurrent laryngeal nerve, resulting in hoarseness due to paralysis of the vocal cord. 129 11 Sectional & Radiographic Anatomy Thorax Sectional Anatomy of the Thorax Fig. 11.1 Transverse section through the thoracic inlet region of the thorax Inferior view. Brachiocephalic trunk Manubrium Clavicle Left brachiocephalic v. Left common carotid a. First rib Right brachiocephalic v. Phrenic n. Trachea Left vagus n. Esophagus Left subclavian a. Right lung, superior lobe Second rib T3 vertebra Sympathetic trunk Spinal cord Left lung, superior lobe Third rib Fig. 11.2 Transverse section through the mid region of the thorax Inferior view. Right lung, superior lobe Internal thoracic a. and v. Sternum Right ventricle Costomediastinal recess Interventricular septum Horizontal fissure of right lung Left ventricle Right atrium Left lung, superior lobe Right lung, middle lobe Phrenic n. (between fibrous pericardium and parietal pleura, mediastinal part) Left atrium Oblique fissure of right lung Oblique fissure of left lung Esophagus Thoracic duct Thoracic (descending) aorta Azygos v. Right lung, inferior lobe 130 Left vagus n. (anterior vagal trunk) Sympathetic trunks Hemiazygos v. Left lung, inferior lobe Superior vena cava Pulmonary trunk Ascending aorta Ascending aorta RA Pulmonary trunk LV A Fig. 11.3 Coronal section through heart and similar MRI A Image displays left ventricular outflow tract (LVOT) during diastole. B Corresponding coronal (frontal) anatomical cross section of the heart, anterior view. Cardiac apex RV Interventricular septum LV RA Interatrial septum LA Opening of pulmonary veins A Fig. 11.4 Transverse section through heart and similar MRI A Image displays the atrioventricular connections of both the right and left sides of the heart during diastole (fourchamber view). B Corresponding transverse anatomical cross section of the heart, inferior view. Lung Right atrium (RA) Liver Aortic valve Left ventricle (LV) Diaphragm B 11 Sectional & Radiographic Anatomy Superior vena cava Right ventricle (RV) Tricuspid valve Interventricular septum Right atrium (RA) Left ventricle (LV) Mitral valve Pulmonary veins Left atrium (LA) Esophagus Ascending aorta B Aortic arch Pulmonary trunk LA RV Aortic valve Infundibulum of the RVOT A Fig. 11.5 Sagittal section of the heart and similar MRI A Image displays the right ventricular outflow tract (RVOT) during diastole. B Corresponding sagittal anatomical cross section of the heart, viewed from the left side. Pulmonary trunk Aortic valve Aortic arch Left main bronchus Left atrium (LA) Right ventricle (RV) Pulmonary veins B 131 Thorax Radiographic Anatomy of the Thorax (I) Fig. 11.6 (Reproduced from Lange S. Radiologische Diagnostik der Thoraxerkrankungen, 4th ed. Stuttgart: Thieme; 2010.) Clavicle Trachea Sternum, manubrium Aortic arch Pulmonary a. Superior vena cava Auricle of left atrium Lower lobe aa. Left ventricle Right atrium Apex of heart Dome of diaphragm A Posterior-anterior (PA) chest radiograph. Anterior view. Trachea Scapula Aortic arch Sternum Retrosternal space Left upper lobe bronchus Right pulmonary a. Left atrium Retrocardiac space Right ventricle Left ventricle Dome of diaphragm B Left lateral chest radiograph. 132 Fig. 11.7 Left bronchogram Anteroposterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Main bronchus Anterior segment of upper lobe Lingula of the superior segment of upper lobe Lobar bronchus Lingula of the inferior segment of upper lobe Segmental bronchus Superior segment of lower lobe Posterior basal segment of lower lobe 11 Sectional & Radiographic Anatomy Apical-posterior segment of upper lobe Anterior-medial basal segment of lower lobe Lateral basal segment of lower lobe Fig. 11.8 MRI of the thorax Coronal view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 3rd ed. New York, NY: Thieme; 2007.) Spinal cord Right pulmonary a. Right main bronchus Left lung Aortic arch Left pulmonary a. Right pulmonary v. Left main bronchus Left pulmonary v. Right lung Esophagus Descending aorta Spleen Liver Thoracic vertebrae, T11 Intervertebral disc T11–T12 133 Thorax Radiographic Anatomy of the Thorax (II) Fig. 11.9 Selective coronary angiography of the left coronary artery in a right anterior oblique position Left coronary a. Left interventricular a. Left circumflex a. Left diagonal aa. Left marginal a. Fig. 11.10 Selective coronary angiography of the right coronary artery in a left anterior oblique projection Left posterolateral a. (Reproduced from Thelen M. et al. Bildgebene Kardiodiagnostik. Stuttgart: Thieme; 2007.) Right coronary a. Right marginal a. Fig. 11.11 CT of the heart Right posterolateral a. Posterior interventricular a. CT angiography. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Right auricle Ascending aorta Left atrium Left pulmonary v. Left coronary a. (LCA) Right coronary a. (RCA) Pulmonary trunk Left auricle Circumflex br. of LCA Marginal br. Anterior interventricular br. of LCA 134 Fig. 11.12 MRI of the heart (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional ­Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Branchiocephalic trunk Aortic valve Right atrium Left ventricle Interventricular septum Right ventricle Brachiocephalic trunk A Left ventricular outflow tract. Right pulmonary vv. Superior vena cava 11 Sectional & Radiographic Anatomy Pulmonary a. Ascending aorta Ascending aorta Pulmonary trunk Right atrium Right atrioventricular (tricuspid) valve Right ventricle B Two chamber view of right ventricle. Fig. 11.13 Aortic arch angiogram Left lateral view. Right thyrocervical trunk Right common carotid a. Right vertebral a. Right subclavian a. Left thyrocervical trunk Left vertebral a. Left subclavian a. Brachiocephalic trunk Left common carotid a. Aortic arch Ascending aorta Descending aorta 135 Thorax Radiographic Anatomy of the Thorax (III) Fig. 11.14 CT of the thorax (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Pectoralis major Rib Sternum Anterior edge of lung in costomediastinal recess A B C Ascending aorta Superior vena cava Left lung Right main bronchus Left main bronchus Descending aorta Scapula Subscapularis Infraspinatus A Pulmonary trunk Ascending aorta Superior vena cava Left pulmonary v. Right pulmonary a. Left atrium Right inferior lobar bronchus Esophagus Left inferior lobar bronchus Azygos v. Descending aorta B Conus arteriosus Right auricle Superior vena cava Ascending aorta Left ventricle Left atrium Left pulmonary v. Esophagus C 136 Descending aorta Right atrium Conus arteriosus Left ventricle Aortic valve Left atrium Right pulmonary v. Left pulmonary v. Esophagus Descending aorta 11 Sectional & Radiographic Anatomy D E F D Right ventricle Interventricular septum Right atrioventricular (tricuspid) valve Left ventricle Right atrium Left atrium Esophagus Descending aorta Sympathetic trunk E Inferior vena cava Esophagus Azygos v. Descending aorta F 137 Abdomen 16 Neurovasculature 12 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 13 Abdominal Wall Bony Framework for the Abdominal Wall . . . . . . . . . . . . . . . Muscles of the Anterolateral Abdominal Wall . . . . . . . . . . . . Rectus Sheath & Posterior Abdominal Wall . . . . . . . . . . . . . . Abdominal Wall Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . Inguinal Region & Canal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inguinal Region & Inguinal Hernias. . . . . . . . . . . . . . . . . . . . . Scrotum & Spermatic Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 144 146 148 150 152 154 14 Abdominal Cavity & Spaces Divisions of the Abdominopelvic Cavity . . . . . . . . . . . . . . . . Peritoneum, Mesenteries & Omenta . . . . . . . . . . . . . . . . . . . Mesenteries & Peritoneal Recesses . . . . . . . . . . . . . . . . . . . . Lesser Omentum & Omental Bursa . . . . . . . . . . . . . . . . . . . . Mesenteries & Posterior Abdominal Wall. . . . . . . . . . . . . . . . 156 158 160 162 164 15 Internal Organs Stomach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Duodenum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jejunum & Ileum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cecum, Appendix & Colon . . . . . . . . . . . . . . . . . . . . . . . . . . . Liver: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Liver: Lobes & Segments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gallbladder & Bile Ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pancreas & Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kidneys & Suprarenal Glands (I) . . . . . . . . . . . . . . . . . . . . . . . Kidneys & Suprarenal Glands (II) . . . . . . . . . . . . . . . . . . . . . . 166 168 170 172 174 176 178 180 182 184 Arteries of the Abdominal Wall & Organs . . . . . . . . . . . . . . . Abdominal Aorta & Renal Arteries . . . . . . . . . . . . . . . . . . . . . Celiac Trunk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superior & Inferior Mesenteric Arteries . . . . . . . . . . . . . . . . . Veins of the Abdominal Wall & Organs . . . . . . . . . . . . . . . . . Inferior Vena Cava & Renal Veins . . . . . . . . . . . . . . . . . . . . . . Portal Vein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superior & Inferior Mesenteric Veins . . . . . . . . . . . . . . . . . . . Lymphatics of the Abdominal Wall & Organs . . . . . . . . . . . . Lymph Nodes of the Posterior Abdominal Wall . . . . . . . . . . . Lymph Nodes of the Supracolic Organs . . . . . . . . . . . . . . . . . Lymph Nodes of the Infracolic Organs . . . . . . . . . . . . . . . . . . Nerves of the Abdominal Wall . . . . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation: Overview . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation & Referred Pain. . . . . . . . . . . . . . . . . Innervation of the Foregut & Urinary Organs . . . . . . . . . . . . Innervation of the Intestines . . . . . . . . . . . . . . . . . . . . . . . . . 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 17 Sectional & Radiographic Anatomy Sectional Anatomy of the Abdomen . . . . . . . . . . . . . . . . . . . 220 Radiographic Anatomy of the Abdomen (I). . . . . . . . . . . . . . 222 Radiographic Anatomy of the Abdomen (II). . . . . . . . . . . . . . 224 12 Surface Anatomy Abdomen Surface Anatomy Fig. 12.1 Palpable structures of the abdomen and pelvis Anterior view. See pp. 2–3 for structures of the back. Rectus abdominis Tendinous intersections Transumbilical plane (L3–4 disk) Anterior superior iliac spine (ASIS) Linea alba External oblique Semilunar line Anterior superior iliac spine (ASIS) Inguinal lig. Pubic symphysis Pubic tubercle Superficial inguinal ring Sartorius Quadriceps femoris Bony prominences. A Musculature. B Fig. 12.2 Quadrants and layers of the abdominopelvic cavity Anterior view. The location of the organs of the abdomen and pelvis can be described by quadrant and layer. Gallbladder Right upper quadrant (RUQ) Right lower quadrant (RLQ) A Quadrants, defined by the intersection of the median plane and the transumbilical plane through the L3–L4 disk. Costal margin (arch) Left upper quadrant (LUQ) Spleen Pancreas Duodenum Left lower quadrant (LLQ) Descending colon Periumbilical region Ascending colon with cecum and vermiform appendix Suprarenal glands C Organs of the middle layer. Liver Stomach Transverse colon Kidneys Abdominal aorta Small intestine ( jejunum and ileum) B Organs of the anterior layer. 140 Ureters Urinary bladder DOrgans of the posterior layer. Table 12.1 Transverse planes through the abdomen Transverse plane midway between the superior borders of the pubic symphysis and the manubrium ② Subcostal plane Plane at the lowest level of the costal margin (the inferior margin of the tenth costal cartilage) ③ Supracrestal plane Plane passing through the summits of the iliac crests ④ Transtubercular plane Plane at the level of the iliac tubercles (the iliac tubercle lies ~5 cm posterolateral to the anterior superior iliac spine) ⑤ Interspinous plane Plane at the level of the anterior superior iliac spines Superior border of manubrium 12 Surface Anatomy ① Transpyloric plane ① ② ③ ④ ⑤ Superior border of pubic symphysis Table 12.2 Regions of the abdomen ① Epigastric region ② Umbilical region ③ Pubic region ④ Left hypochondriac region Midclavicular line Upper abdomen ⑤ Left lateral (lumbar) region ⑥ Left inguinal region ⑦ ① ④ Costal margin (arch) Subcostal plane Mid-abdomen ⑧ ② ⑦ Right hypochondriac region ⑧ Right lateral (lumbar) region ⑨ Right inguinal region ⑤ Supracrestal plane Lower abdomen ⑨ ③ ⑥ Iliac crest Inguinal lig. 141 13 Abdominal Wall Abdomen Bony Framework for the Abdominal Wall Fig. 13.1 Bony framework of the abdomen Anterior view. These bones are the site of attachment for the muscles and ligaments of the anterolateral abdominal wall and form a bony cage that protects certain abdominal organs. 4th rib Body of sternum 6th rib Xiphoid process 8th rib T12 Costal margin L1 10th rib L2 12th rib Transverse processes of lumbar vertebrae L3 Wing (ala) of ilium L4 Iliac tuberosity L5 Iliac crest Sacral promontory Anterior superior iliac spine Arcuate line Iliopubic eminence Ischial spine Superior pubic ramus Pubic tubercle Anterior superior iliac spine Sacrum Fig 13.2 The inguinal ligament Inguinal lig. Pubic tubercle 142 Pubic symphysis Pubic symphysis Male pelvis, anterosuperior view. The inguinal ligament is a palpable landmark that forms the demarcation between the abdominal wall and thigh. It is formed by the inferior edge of the external oblique aponeurosis, the most superficial of the anterior abdominal wall muscles. The inguinal ligament attaches laterally to the anterior superior iliac spine and medially to the pubic tubercle. It is important clinically as it forms the floor of the inguinal canal (see Table 13.2) and the roof of the retro-inguinal space (see Fig. 34.31). Fig. 13.3 Abdominal wall muscle attachment sites Left hip bone. Muscle origins are in red, insertions in blue. 13 Abdominal Wall Iliac crest Quadratus lumborum Transversus abdominis Internal oblique External oblique Auricular surface of ilium Anterior superior iliac spine Psoas minor Anterior inferior iliac spine Conjoint tendon Rectus abdominis, lateral head Arcuate line Superior pubic ramus Pyramidalis Quadratus lumborum Rectus sheath, anterior layer Transversus abdominis Rectus abdominis, medial head A Superior view. Posterior superior iliac spine Greater sciatic notch Psoas minor Ischial spine Superior pubic ramus Ischial tuberosity B Medial view. 143 Abdomen Muscles of the Anterolateral Abdominal Wall The muscles of the anterolateral abdominal wall consist of the external and internal obliques and the transversus ­abdominis. The posterior or deep abdominal wall muscles (notably the psoas major) are functionally hip muscles (see p. 148). Fig. 13.4 Muscles of the abdominal wall Right side, anterior view. Pectoralis major (sternocostal part) Sternum Serratus anterior Pectoralis major (abdominal part) Linea alba External oblique External oblique aponeurosis Rectus sheath, anterior layer Umbilicus Internal intercostals Costal cartilage Sternum External intercostals Xiphoid process Rectus abdominis Inguinal lig. Superficial inguinal ring External oblique Spermatic cord, cremaster muscle A Superficial abdominal wall muscles. Fundiform lig. of the penis Linea alba Internal oblique Internal oblique aponeurosis Umbilicus Anterior superior iliac spine Inguinal lig. Rectus sheath, anterior layer Spermatic cord, cremaster muscle B Removed: External oblique, pectoralis major, and serratus anterior. 144 13 Abdominal Wall Sternum Tendinous intersections Rectus abdominis External oblique Linea alba Internal oblique Umbilicus Transversus abdominis Inguinal lig. Transversus abdominis aponeurosis Sternum Pyramidalis Rectus sheath, posterior layer Spermatic cord, cremaster muscle C Removed: External and internal obliques. External oblique Linea alba Internal oblique Transversus abdominis Umbilicus Semilunar line Arcuate line Rectus abdominis Transversalis fascia Inguinal lig. Rectus sheath, anterior layer Deep inguinal ring Spermatic cord DRemoved: Rectus abdominis. 145 Abdomen Rectus Sheath & Posterior Abdominal Wall Fig. 13.5 The rectus sheath The rectus sheath encloses the rectus abdominis and pyramidalis muscles on either side of the midline. Its anterior and posterior layers are formed by the aponeuroses of the anterolateral muscles as they split to pass around the rectus muscles. An arcuate line marks the inferior extent of the posterior layer, the point at which all of the aponeuroses pass anterior to the rectus muscles. APosterior (interior) view of the anterior abdominal wall. Peritoneum and transversalis fascia have been removed on the left side to reveal the rectus sheath. Parietal pleura, diaphragmatic part Central tendon Diaphragm Costal part of diaphragm Linea alba Parietal peritoneum Transversalis fascia External oblique Plane of section in figure B Internal oblique Rectus sheath, posterior layer Transversus abdominis Transversus abdominis Umbilicus Arcuate line Plane of section in figure C Iliacus Rectus abdominis Iliopubic tract Rectus abdominis Rectus sheath, anterior layer Membranous layer, subcutaneous tissue Linea alba External oblique aponeurosis External oblique Internal oblique Transversus abdominis Preperitoneal Parietal Transversalis fat peritoneum fascia Rectus sheath, Transversus Internal posterior layer abdominis oblique aponeurosis aponeurosis BSection through the abdominal wall superior to the arcuate line. Internal oblique aponeurosis External oblique aponeurosis Transversus abdominis aponeurosis Rectus sheath, anterior layer Linea alba Transversalis fascia CSection through the abdominal wall inferior to the arcuate line. 146 Skin Fatty layer Parietal peritoneum Membranous layer Subcutaneous tissue Fig. 13.6 Muscles of the posterior abdominal wall Internal intercostals Transversus thoracis Caval opening Central tendon Body of sternum Diaphragm, costal part Aortic hiatus T8 vertebral body Esophageal hiatus T10 vertebral body T12 vertebral body Costal arch Transversus abdominis Rectus sheath, posterior layer Iliac crest L5 vertebral body 13 Abdominal Wall Manubrium Caval opening Esophageal hiatus Right crus Median arcuate lig. Lateral arcuate lig. Medial arcuate lig. Quadratus lumborum Psoas minor Central tendon Diaphragm, costal part Diaphragm, lumbar part, and left crus Aortic hiatus Transversus abdominis Psoas major Iliacus Psoas major Iliacus Piriformis Obturator internus Pubic symphysis Sacrospinous lig. Iliopsoas Gluteus maximus A Midsagittal section with diagraphm in intermediate position. B Coronal section with diaphragm in intermediate position. Central tendon Inferior vena cava Median arcuate lig. Right crus Esophagus Crural sling Aorta Left crus Clinical box 13.1 Diaphragmatic hernias C Apertures of the diaphragm with vessels transected. Anterior view. The caval opening is located to the right of the midline, those for the esophagus and aorta are to the left. Note that the crura of the diaphragm typically extend inferiorly as far as the L3 vertebra on the right and L2 vertebra on the left. In diaphragmatic hernias, abdominal viscera prolapse into the thorax through a congenital or acquired opening in the diaphragm. By far the most common herniation site is the esophageal hiatus, accounting for 90% of cases. “Sliding” hernias, which account for 85% of these hiatal hernias, occur when the distal end of the esophagus and the cardia of the stomach slide upward into the thorax through the esophageal hiatus. 147 Abdomen Abdominal Wall Muscle Facts Fig. 13.7 Anterior abdominal wall muscles Anterior view. Fig. 13.8 Anterolateral abdominal wall muscles Fig. 13.9 Posterior abdominal wall muscles Anterior view. Anterior view. The psoas major and iliacus are together known as the iliopsoas inferiorly. ⑧ D A G F Linea alba ⑦ ⑥ S A External oblique. Table 13.1 B Internal oblique. C Transversus abdominis. Abdominal wall muscles Muscle Origin Insertion Innervation Action ① Rectus abdominis Lateral head: Crest of pubis to pubic tubercle Medial head: Anterior region of pubic symphysis Cartilages of 5th to 7th ribs, xiphoid process of sternum Intercostal nn. (T5– Flexes trunk, compresses abdomen, stabilizes T11) , subcostal n. pelvis (T12) ② Pyramidalis Pubis (anterior to rectus abdominis) Linea alba (runs within the rectus sheath) Subcostal n. (T12) Linea alba, pubic tubercle, anterior iliac crest Intercostal nn. (T7–T11) , subcostal n. (T12) Anterior abdominal wall muscles Tenses linea alba Anterolateral abdominal wall muscles ③ External oblique 5th to 12th ribs (outer surface) ④ Internal oblique Thoracolumbar fascia (deep layer), iliac crest (intermediate line), anterior superior iliac spine, iliopsoas fascia ⑤ Transversus abdominis 7th to 12th costal cartilages (inner surfaces), thoracolumbar fascia (deep layer), iliac crest, anterior superior iliac spine (inner lip), iliopsoas fascia 10th to 12th ribs (lower borders), linea alba (anterior and posterior Intercostal layers) nn. (T7–T11) , subcostal n. (T12) iliohypogastric n., ilioinguinal n. Linea alba, pubic crest Unilateral: Flexes trunk to same side, rotates trunk to opposite side (external oblique) or same side (internal oblique) Bilateral: Flexes trunk, compresses abdomen, stabilizes pelvis Unilateral: Rotates trunk to same side Bilateral: Compresses abdomen Posterior abdominal wall muscles Psoas minor* (see Fig. 31.19) ⑥ Psoas Superficial layer T12, L1 vertebrae and intervertebral disk (lateral surfaces) T12–L4 vertebral bodies and associated intervertebral disks (lateral surfaces) major Deep layer ⑦ Iliacus Iliac fossa ⑧ Quadratus Iliac crest and iliolumbar lig. (not shown) lumborum 148 L1–L5 (costal processes) Pectineal line, iliopubic ramus, iliac fascia; lowermost fibers may reach inguinal lig. Weak flexor of the trunk L1–L2 (L3) spinal nn. Femur (lesser trochanter), joint insertion as iliopsoas muscle Hip joint: Flexion and external rotation Lumbar spine (with femur fixed): Unilateral: Contraction flexes trunk laterally Bilateral: Contraction raises trunk from supine position Femoral n. (L2–L4) Unilateral: Flexes trunk to same side 12th rib, L1–L4 vertebrae (costal processes) * Approximately 50% of the population has this muscle. For the diaphragm see pp. 64–65. Subcostal n. (T12), L1–L4 spinal nn. Bilateral: Bearing down and expiration, stabilizes 12th rib Fig. 13.10 Anterior, anterolateral, and posterior abdominal wall muscles 5th rib Anterior view. External oblique 5th rib Linea alba Xiphoid process External oblique aponeurosis Umbilical ring 13 Abdominal Wall Xiphoid process Outer lip of iliac crest Linea alba Quadratus lumborum Superficial inguinal ring Tendinous intersections Psoas major Iliac crest Anterior superior iliac spine Inguinal lig. B External oblique. Iliac fossa Rectus abdominis Iliacus Xiphoid process Inguinal lig. 10th rib Linea alba Internal oblique aponeurosis Iliopsoas Internal oblique Pubic tubercle Iliac crest, intermediate line Anterior superior iliac spine Lesser trochanter Pubic symphysis Inguinal lig. Pyramidalis A Anterior and posterior muscles. Pubic symphysis C Internal oblique. Fig. 13.11 Anterior and lateral abdominal wall muscles as a functional unit Sternum Body of sternum Xiphoid process Linea alba Linea alba Rectus sheath, posterior layer Transversus abdominis Arcuate line External oblique Rectus sheath, anterior layer Internal oblique Transversus abdominis Transversus abdominis aponeurosis Iliac crest Anterior superior iliac spine Inguinal lig. Pubic symphysis Rectus abdominis DTransversus abdominis. 149 Abdomen Inguinal Region & Canal The inguinal region is the junction of the anterior abdominal wall and the anterior thigh. The inguinal canal in the male is an important site for the passage of structures into and out of the abdominal cavity (e.g., components of the spermatic cord). External oblique Internal oblique Transversus abdominis Rectus abdominis Linea alba Fig. 13.12 Inguinal region Rectus sheath Right side, anterior view. Iliopsoas Membranous layer, subcutaneous tissue Femoral n. Iliopectineal arch External oblique aponeurosis Inguinal lig. Ilioinguinal n. Genitofemoral n., genital br. Femoral a. and v. Reflected inguinal lig. Spermatic cord Lacunar lig. Pubic tubercle Superficial inguinal ring A Male. Lateral crus Intercrural fibers Medial crus Cremaster m. and cremasteric fascia Pectineus Plane of section in Table 13.2 External spermatic fascia Superficial inguinal ring Lateral crus External oblique aponeurosis Site of inguinal lig. Medial crus Genitofemoral n., genital br. A. of round lig. V. of round lig. B Female. 150 Clinical box 13.2 Intercrural fibers Fat pad Ilioinguinal n. Round lig. of uterus Gender differences of the inguinal canal The inguinal canal is an oblique pathway through the inferior part of the anterior abdominal wall. In the male, it represents the path through which the testis migrated from the posterior abdominal wall into the scrotum during the perinatal period. It’s traversed by the spermatic cord (see Table 13.4), which connects the testis to the rest of the genitourinary system. The female inguinal canal is smaller and contains only the round ligament with its neurovasculature. This ligament is a remnant of the distal portion of the embryonic gubernaculum, a structure originally present in both males and females but which regresses in the male with descent of the testes. Table 13.2 Structures of the inguinal canal Structures Formed by Roof Wall Posterior wall Floor ① External oblique aponeurosis ② Internal oblique m. ③ Transversus abdominis m. ④ Transversalis fascia ④ ⑤ ① Iliopubic tract Pectineal lig. Lacunar lig. Superior pubic ramus ⑤ Parietal peritoneum ⑥ Inguinal lig. (densely interwoven fibers of the lower external oblique aponeurosis and adjacent fascia lata of the thigh) Superficial inguinal ring Opening in external oblique aponeurosis; bounded by medial and lateral crus, intercrural fibers, and reflected inguinal lig. Deep inguinal ring Outpouching of the transversalis fascia lateral to the lateral umbilical fold (inferior epigastric vessels) Openings Membranous layer, subcutaneous tissue Ilioinguinal n. Spermatic cord ⑥ 13 Abdominal Wall Anterior wall ③ ② Pectineus Fascia lata Sagittal section through plane in Fig. 13.12A. Fig. 13.13 Dissection of the male inguinal region Right side, anterior view. External oblique aponeurosis Inguinal lig. Lateral crus Intercrural fibers Location of deep inguinal ring Fig. 13.14 Opening of the inguinal canal Right side, anterior view. External oblique aponeurosis Internal oblique Iliohypogastric n., anterior cutaneous br. Medial crus Superficial inguinal ring Spermatic cord Genitofemoral n., genital br. Ilioinguinal n. Superficial inguinal ring (cut open) A Superficial layer. Spermatic cord with cremaster m. and cremasteric fascia Internal oblique A Divided: External oblique aponeurosis. Spermatic cord with cremaster m. B Removed: External oblique aponeurosis. Transversus abdominis Inguinal lig. Transversalis fascia Internal oblique Transversus abdominis Inferior epigastric a. and v., interfoveolar lig. Deep inguinal ring Ilioinguinal n. Rectus abdominis Spermatic cord with internal spermatic fascia Hesselbach’s triangle Transversalis fascia Reflected inguinal lig. Femoral a. and v. Spermatic cord, internal spermatic fascia B Divided: Internal oblique and cremaster mm. C Removed: Internal oblique m. 151 Abdomen Inguinal Region & Inguinal Hernias Fig. 13.15 Sites of herniation through the anterior abdominal wall Diaphragm Coronal section, male, posterior ­(internal) view. Parietal peritoneum AThe three fossae of the anterior abdominal wall (circled) are sites of potential herniation through the wall. Transversalis fascia Rectus sheath, posterior layer Arcuate line Rectus abdominis Inferior epigastric a. and v. Deep circumflex iliac a. and v. Falciform lig. Round lig. of liver, paraumbilical veins Umbilicus Median umbilical fold Medial umbilical fold Lateral umbilical fold Lateral inguinal fossa (deep inguinal ring) Iliacus Psoas major External iliac a. and v. Ductus deferens Medial inguinal fossa (Hesselbach‘s triangle) Supravesical fossa Bladder Prostate BInternal hernial openings in the male inguinal region. Detail from A. Peritoneum and transversalis fascia have been removed to reveal the hernia openings. Color shading indicates openings for supravesical (green), indirect (teal) and direct (purple) hernias (see Table 13.3). Peritoneum Transversalis fascia Arcuate line Transversus abdominis Rectus abdominis Inferior epigastric a. and v. Iliopubic tract Femoral n. Iliopsoas Iliacus Psoas major Medial umbilical fold Lateral inguinal fossa (deep inguinal ring) Interfoveolar lig. Medial inguinal fossa (Hesselbachʼs triangle) Supravesical fossa Iliopectineal arch Testicular a. and v. Femoral ring External iliac a. and v. Pectineal lig. Ductus deferens 152 Right side, anterior view. Transversalis fascia Deep inguinal ring (lateral inguinal fossa) Lateral umbilical fold Transversus abdominis Medial inguinal fossa (Hesselbach's triangle) Internal oblique 13 Abdominal Wall Fig. 13.16 Schematic of the male inguinal canal and its relation to structures of the abdominal wall Medial umbilical fold (obliterated umbilical a.) External oblique aponeurosis Superficial investing fascia Rectus abdominis Subcutaneous tissue (fatty and membranous layers) Inferior epigastric a. and v. Superficial inguinal ring Scrotal skin with dartos m. and fascia Rectus sheath, anterior layer Cremaster m. and cremasteric fascia Pampiniform plexus, testicular a. and ductus deferens External spermatic fascia Internal spermatic fascia Epididymis Testis Scrotal cavity Table 13.3 Hernias of the inguinal region Superficial inguinal ring Most inguinal hernias occur in males. All are located above the inguinal ligament and, if large enough, protrude externally through the superficial ring. However, the internal site of origin, and therefore structure of the hernia sac (covering), differ among types. Femoral hernias, more common in women, originate at the femoral ring below the inguinal ligament and emerge at the saphenous opening in the thigh. Hernia type Site of origin Hernia sac Indirect inguinal (congenital or acquired) Lateral inguinal fossa (deep inguinal ring) lateral to inferior epigastric vessels Peritoneum, transversalis fascia, cremaster m. Direct inguinal (acquired) Medial inguinal fossa (Hesselbach’s triangle), medial to inferior epigastric vessels Peritoneum, transversalis fascia Femoral Femoral ring, inferior to inguinal lig. Cribiform fascia of saphenous opening A Indirect inguinal hernia B Direct inguinal hernia 153 Abdomen Scrotum & Spermatic Cord The coverings of the scrotum, testis, and spermatic cord are continuations of muscular and fascial layers of the anterior abdominal wall, as are those of the inguinal canal. Fig. 13.17 Scrotum and spermatic cord Anterior view. Superficial inguinal ring Femoral a. and v. Spermatic cord Fundiform lig. of the penis Superficial penile (Colles’) fascia Root of the penis Scrotal septum External spermatic fascia covering spermatic cord and testis Dartos m. and fascia Scrotal skin Gubernaculum A Structure and contents of the scrotum. Superficial inguinal ring Cremasteric fascia and cremaster m. External spermatic fascia Internal spermatic fascia Femoral a. and v. Testicular plexus Testicular a. Pampiniform plexus (testicular vv.) Epididymis Tunica vaginalis Parietal layer Ductus deferens External spermatic fascia Processus vaginalis (obliterated) Dartos m. Visceral layer Scrotum B Fascial and muscular layers of the spermatic cord have been opened to reveal its contents. 154 Contents of the spermatic cord Table 13.4 Contents External spermatic fascia ① Ilioinguinal n. Cremasteric muscle ② Cremasteric a. and v. ③ Genitofemoral n., genital br. Internal spermatic fascia ④ ⑧ ⑨ ⑥ ④ A. and v. of ductus deferens ⑤ Ductus deferens ⑥ Testicular a. ⑦ Processus vaginalis (obliterated) ⑧ Testicular (nerve) plexus ⑨ Pampiniform (venous) plexus Fig. 13.18 Testis and epididymis ⑦ ① ⑤ ③ External spermatic fascia Fibrous stroma Cremasteric fascia Cremaster m. Internal spermatic fascia ② Skin Left lateral view. 13 Abdominal Wall Surrounding layer Membranous layer, subcutaneous tissue Internal spermatic fascia External spermatic fascia Cremasteric fascia and cremaster m. Testicular a. Pampiniform plexus Testicular plexus Dartos fascia Tunica vaginalis, parietal layer Epididymis, body Epididymis, head Testis with tunica vaginalis, visceral layer Glans of penis Scrotum Table 13.5 Septum 6b Cavity of tunica vaginalis 6a Lobule Covering layer Scrotal septum ③ Mediastinum testis with rete testis ④ Epididymis, head Tunica albuginea Testicular a. Ductus deferens Transverse section through right testis, superior view. ⑤ Pampiniform plexus Derived from ① Scrotal skin Abdominal skin ② Dartos m. and fascia Membranous layer, subcutaneous tissue ③ External spermatic fascia External oblique aponeurosis and superficial investing fascia ④ Cremaster m. and cremasteric fascia Internal oblique m. ⑤ Internal spermatic fascia Transversalis fascia 6a Tunica vaginalis, parietal layer 6b Tunica vaginalis, visceral layer ① ② Coverings of the testis Peritoneum * The transversus abdominis has no contribution to the spermatic cord or covering of the testis. 155 14 Abdominal Cavity & Spaces Abdomen Divisions of the Abdominopelvic Cavity Fig. 14.1 Organs of the abdominopelvic cavity Midsagittal section, male, viewed from the left. Sternum Liver Esophagus Liver, bare area Omental foramen Hepatogastric lig. (lesser omentum) Omental bursa (lesser sac) Pancreas, neck Stomach Middle colic a. Transverse mesocolon Celiac trunk Splenic a. and v. Left renal a. Superior mesenteric a. Left renal v. Pancreas, uncinate process Abdominal aorta Transverse colon Duodenum, horizontal part Greater omentum Mesentery Jejunum and ileum L5 vertebra Rectus abdominis Urinary bladder Ductus deferens, ampulla Bulbospongiosus Left common iliac a. and v. Rectovesical pouch Rectum Prostate Deep transverse perineal Scrotum, septum Clinical box 14.1 Acute abdominal pain Acute abdominal pain (“acute abdomen”) may be so severe that the abdominal wall becomes extremely sensitive to touch (“guarding”) and the intestines stop functioning. Causes include organ inflammation such 156 as appendicitis, perforation due to a gastric ulcer (see p. 167), or organ blockage by a stone, tumor, etc. In women, gynecological processes or ectopic pregnancies may produce severe abdominal pain. Fig. 14.2 Divisions of the pelvic and abdominal cavities 14 Abdominal Cavity & Spaces Each column of diagrams shows a midsagittal section viewed from the left side, as well as two axial sections, one at the L1 level and the other at the lower part of the sacrum, both viewed from below. Omental bursa Linea terminalis Rectovesical pouch A D G B E C F A–C Topography of body cavities: abdominal cavity and pelvic cavity (imaginary line separating the two cavities is the linea terminalis). Omental bursa Rectovesical pouch D–F Serous cavities (peritoneal spaces): abdominal peritoneal cavity and pelvic peritoneal cavity. H I Retroperitoneal space Subperitoneal space G–I Connective tissue spaces (extraperitoneal spaces): retroperitoneal space and subperitoneal space; serous cavities and extraperitoneal spaces are separated by peritoneum. 157 Abdomen Peritoneum, Mesenteries & Omenta Organs in the abdominopelvic cavity are classified by the presence of surrounding peritoneum (the serous membrane lining the cavity) and a mesentery (a double layer of peritoneum that connects the organ to the abdominal wall) (see Table 14.1). Fig. 14.3 Peritoneal cavity Bare area of the liver Lesser omentum Omental bursa Parietal peritoneum Transverse mesocolon Mesentery (of the small intestine) Parietal peritoneum Greater omentum Visceral peritoneum Rectovesical space A Midsagittal section through the male abdominopelvic cavity, viewed from the left. The peritoneum is shown in red. Clinical box 14.2 Peritonitis and ascites Bacterial contamination of the perito­neum following surgery or rupture of an inflamed organ (duode­num, gallbladder, appendix) results in peritonitis, inflammation of the peritoneum. It is accompanied by severe abdominal pain, tenderness, nausea, and fever and can be fatal when generalized throughout the peritoneal cavity. It often results in ascites, the accumulation of excess peritoneal fluid due to a change in concen­tration gradients that 158 results in loss of capillary fluid. Ascites can also accompany other pathologic conditions, such as metastatic liver cancer and portal hypertension. In these cases, many liters of ascitic fluid can accumulate in the peritoneal cavity. The fluid is aspirated by paracentesis. The needle is carefully inserted through the abdominal wall so as to avoid the urinary bladder and inferior epigastric vessels. Fig. 14.5 Relationship of an intraperitoneal organ to the mesentery and peritoneum Arrows indicate blood vessels in the mesentery. Transverse section, superior view (See Table 14.2). Mesentery Intraperitoneal organ (e.g., jejunum) Parietal peritoneum Visceral peritoneum Parietal layer Mesentery Peritoneal cavity Secondarily retroperitoneal organ (e.g., ascending colon) Extraperitoneal or primarily retroperitoneal organ (e.g., kidney) Abdominal aorta Visceral layer Peritoneum Retroperitoneal space Intraperitoneal organ Lumbar spine Fig. 14.6 Structure of the greater and lesser omenta and their relation to the omental bursa Liver Lesser omentum Omental bursa Pancreas Stomach Duodenum Gastrocolic lig. Transverse mesocolon Transverse colon Mesentery (of the small intestine) Greater omentum Mesenteries and omenta Table 14.1 Sagittal section, left lateral view. Table 14.2 Peritoneal cavity 14 Abdominal Cavity & Spaces Fig. 14.4 Schematic showing peritoneal relations of intraperitoneal and extraperitoneal (primary and secondary retroperitoneal) organs of the abdomen Mesenteries Mesentery (of the small intestine) Transverse mesocolon Sigmoid mesocolon Mesoappendix Omenta Lesser omentum Greater omentum Reflections of the peritoneum that connect organs to the body wall or to another organ allow normal mobility of the gastrointestinal tract while preventing excessive movement. A mesentery is a double layer of peritoneum that connects intraperitoneal organs to the posterior abdominal wall and transmits nerves and vessels. An omentum is a double layer of peritoneum that connects the stomach and duodenum to another organ or to the posterior abdominal wall. Organs of the abdominopelvic cavity classified by their relationship to the peritoneum Location Organs Intraperitoneal organs: These organs have a mesentery and are completely covered by the peritoneum. Abdominal peritoneal • Stomach • Gallbladder • Small intestine (jejunum, ileum, some of • Cecum with vermiform appendix (portions of variable the superior part of the duodenum) size may be retroperitoneal) • Spleen • Large intestine (transverse and sigmoid colons) • Liver Pelvic peritoneal • Uterus (fundus and body) • Ovaries • Uterine tubes Extraperitoneal organs: These organs either have no mesentery or lost it during development. Retroperitoneal Primarily • Kidneys and ureters Secondarily • Duodenum (descending, horizontal, and ascending) • Pancreas Infraperitoneal/subperitoneal • Urinary bladder • Distal ureters • Prostate • Suprarenal glands • Seminal glands • Uterine cervix • Uterine cervix • Ascending and descending colon and cecum • Rectum (upper 2/3) • Vagina • Rectum (lower 1/3) 159 Abdomen Mesenteries & Peritoneal Recesses The peritoneal cavity is divided into the large greater sac and small omental bursa (lesser sac). The greater omentum is an apron-like fold of peri­toneum suspended from the greater curvature of the stomach and covering the anterior surface of the transverse colon. The attach- ment of the transverse mesocolon on the anterior surface of the descending part of the duodenum and the pancreas divides the peritoneal cavity into a supracolic compartment (liver, gallbladder, and stomach) and an infracolic compartment (intestines). Fig. 14.7 Dissection of the peritoneal cavity Falciform lig. of liver Liver, left lobe Round lig. of liver Anterior view. Stomach Liver, right lobe Left colic flexure Gallbladder Transverse colon Ascending colon Greater omentum Tenia coli Ileum Lateral umbilical fold (with inferior epigastric a. and v.) Rectus abdominis Medial umbilical fold (with obliterated umbilical a.) Arcuate Median umbilical fold line (with obliterated urachus) A Greater sac. Retracted: Abdominal wall. Greater omentum (reflected superiorly) Transverse colon Transverse mesocolon with middle colic a. and v. Ascending colon Tenia coli Ileum B Infracolic compartment, the portion of the peritoneal cavity below the attachment of the transverse mesocolon. Reflected: Greater omentum and transverse colon. 160 Parietal peritoneum Jejunum (covered by visceral peritoneum) CMesentery (of the small intestine). Reflected: Greater omentum, transverse colon, small intestine. 14 Abdominal Cavity & Spaces Greater omentum Transverse colon Root of mesentery Convoluted small intestine Ascending colon Superior iliocecal recess Cecum Greater omentum (reflected superiorly) Left colic flexure Superior duodenal recess Mesentery, root Inferior duodenal recess Descending colon Sigmoid colon Sigmoid mesocolon Inferior iliocecal recess Mesoappendix Intersigmoidal recess Appendix Retrocecal recess DMesenteries and mesenteric recesses in the infracolic compartment. Reflected: Greater omentum, transverse colon, small intestines, and sigmoid colon. 161 Abdomen Lesser Omentum & Omental Bursa The omental bursa, or lesser sac, is the portion of the peritoneal cavity behind the stomach and the lesser omentum (a double-layered peritoneal structure connecting the lesser curvature of the stomach Fig. 14.8 The lesser omentum and the proximal part of the duodenum to the liver). The omental bursa communicates with the greater sac via the omental (epiploic) foramen, located posterior to the free edge of the lesser omentum. Stomach Gallbladder Anterior view with liver retracted superiorly. The arrow points to the omental foramen, the opening into the omental bursa, posterior to the lesser omentum. Diaphragm Hepatogastric lig. Hepatoduodenal lig. Lesser omentum Duodenum Greater omentum Fig. 14.9 Omental bursa in situ Anterior view. Divided: Gastrocolic ligament. Retracted: Liver. Reflected: Stomach. Gallbladder Vestibule of omental bursa Omental foramen Common hepatic a. Liver, right lobe Duodenum, descending part Right kidney Right colic flexure Ascending colon Greater omentum 162 Stomach, greater curvature Gastrocolic lig. Stomach, posterior surface Gastrosplenic lig. Left gastric a. Left suprarenal gland Left kidney, superior pole Splenic a. Spleen Celiac trunk Phrenicocolic lig. Pancreas Transverse mesocolon Middle colic a. and v. Gastrocolic lig. Transverse colon Descending colon Fig. 14.10 Location of the omental bursa Liver Transverse section, inferior view. Pancreas Omental bursa 14 Abdominal Cavity & Spaces Stomach Splenic recess of omental bursa Spleen Inferior Abdominal Left vena cava aorta kidney Fig. 14.11 Boundaries and walls of the omental bursa (lesser sac) Anterior view. Liver, caudate lobe Gallbladder Hepatoduodenal lig. (lesser omentum) Liver, right lobe Liver, left lobe Cardiac orifice Spleen Duodenum Pancreas Greater omentum Gastrocolic lig. (cut) Diaphragm, hepatic surface Inferior vena cava Transverse colon Splenic recess of omental bursa Superior recess of omental bursa Duodenum Inferior recess of omental bursa Transverse mesocolon A Boundaries of the omental bursa (lesser sac). Table 14.3 Vestibule of omental bursa Diaphragm Pancreas Hepatoduodenal lig. (lesser omentum, cut) B Posterior wall of the omental bursa (lesser sac). Boundaries of the omental bursa Direction Boundary Recess Anterior Lesser omentum, gastrocolic lig. — Inferior Transverse mesocolon Inferior recess Superior Liver (with caudate lobe) Superior recess Posterior Pancreas, aorta (abdominal part), celiac trunk, splenic a. and v., gastrosplenic fold, left suprarenal gland, left kidney (superior pole) — Liver, duodenal bulb — Posterior Inferior vena cava, diaphragm (right crus) Splenic recess Superior Liver (caudate lobe) Right Left Spleen Spleen, gastrosplenic lig. Table 14.4 Boundaries of the omental foramen The communication between the greater sac and lesser sac (omental bursa) is the omental (epiploic) foramen (see arrow in Fig. 14.9). Direction Boundary Anterior Hepatoduodenal lig. with the portal v., proper hepatic a., and bile duct Inferior Duodenum (superior part) 163 Abdomen Mesenteries & Posterior Abdominal Wall Fig. 14.12 Mesenteric attachments of intraperitoneal organs Anterior view. Removed: Stomach, jejunum and ileum, and transverse and sigmoid colons. Retracted: Liver. Liver, right lobe Round lig. of liver Hepatogastric lig. (lesser Liver, omentum, cut) left lobe Cardiac orifice Superior border Spleen Gastric surface Gallbladder Hepatoduodenal lig. (lesser omentum) Omental foramen Gastrosplenic lig. Pancreas Duodenum, superior part Stomach, pyloric part Transverse mesocolon, root Left colic flexure Greater omentum (cut) Transverse colon Right colic flexure Duodenojejunal flexure Transverse colon Duodenum, horizontal part Mesentery (cut) Descending colon Tenia coli Transversus abdominis, internal and external oblique Ascending colon Terminal ileum Sigmoid mesocolon (cut) Cecum Rectum Lateral umbilical fold (with inferior epigastric a. and v.) Rectus abdominis Medial umbilical fold (with obliterated umbilical a.) Median umbilical fold (with obliterated urachus) Transverse mesocolon L4 Mesentery Sigmoid mesocolon Fig. 14.13 Location of mesenteric sites of connection to the abdominal wall 164 Fig. 14.14 Posterior wall of the peritoneal cavity Parietal Diaphragm, Hepatic Inferior Cardiac orifice peritoneum hepatic surface vv. vena cava of stomach Left suprarenal gland Gastrosplenic lig. Splenic a. and v. Hepatoduodenal lig. (with portal v., hepatic a., and bile duct) Right kidney Pancreas, body and tail Left kidney Superior part Descending part Pancreas, head Duodenum Left colic a. and v. Descending colon (site of attachment) Superior mesenteric a. and v. Inferior mesenteric a. Horizontal part Ascending part Abdominal aorta Duodenum 14 Abdominal Cavity & Spaces Right suprarenal gland Anterior view. Removed: All intraperitoneal organs. Revealed: Structures of the retroperitoneum (see Table 14.2 and p. 250). Transversus abdominis, internal and external oblique Paracolic gutter Parietal peritoneum Mesenteric root Right common iliac a. and v. Ascending colon (site of attachment) Mesoappendix Sigmoid mesocolon Left ureter Right ureter External iliac a. Rectum Fig. 14.15 Drainage spaces and recesses within the peritoneal cavity Anterior view. Subhepatic recess Subphrenic recess Hepatic surface of diaphragm Left paracolic gutter Inferior vena cava Transverse mesocolon (root) Hepatoduodenal ligament Spleen Right kidney Left kidney Duodenum Hepatorenal recess Superior duodenal recess Site of attachment of ascending colon Inferior duodenal recess Mesentery (root) Right paracolic gutter Site of attachment of descending colon Superior ileocecal recess Left paracolic gutter Sigmoid mesocolon (root) Inferior ileocecal recess Right infracolic space Left infracolic space A Anterior view with the greater omentum and small intestine removed; preferred metastatic sites (see blue stars). Retrocecal recess Rectovesical pouch Intersigmoid recess B Posterior wall of the peritoneal cavity, anterior view. The mesenteric roots and sites of organ attachment create partially bounded spaces (recesses or sulci) where peritoneal fluid can flow freely. 165 15 Internal Organs Abdomen Stomach Fig. 15.1 Stomach: Location RUQ LUQ Fig. 15.2 Relations of the stomach Lesser omentum (hepatogastric lig.) Stomach Pancreas Transpyloric plane Omental bursa Liver A Anterior view. Left kidney Phrenic surface Suprarenal surface Splenic surface Renal surface Fundus Anterior view. Phrenic surface Epigastric surface B Transverse section, inferior view. Fig. 15.3 Stomach Hepatic surface Spleen Inferior Abdominal vena cava aorta A Anterior view. Esophagus Pancreatic surface Esophagus Colomesocolic surface Cardia B Posterior view. Lesser curvature Duodenum Hepatic surface Greater curvature Pyloric Angular canal notch Body Endoscopic light source Fundus Esophagus, adventitia Esophagus, muscular coat, longitudinal layer Pyloric antrum A Anterior wall. Esophagus Duodenum, superior part Pyloric sphincter Cardia Outer longitudinal layer Middle circular layer Inner oblique layer Duodenum Pyloric sphincter Angular notch Pyloric orifice C Interior. Removed: Anterior wall. 166 Body with longitudinal rugal folds Muscular coat Rugal folds B Muscular layers. Removed: Serosa and subserosa. Windowed: Muscular coat. The stomach, an intraperitoneal organ, resides primarily in the left ­upper quadrant. Double layers of peritoneum extend superiorly from its Anterior view of the opened upper abdomen. Arrow indicates the omental foramen. Liver, right lobe Falciform lig. of liver Liver, left lobe Esophagus Parietal peritoneum Diaphragm Stomach, fundus Stomach, cardia Hepatoesophageal lig. Gallbladder Hepatoduodenal lig. 15 Internal Organs Fig. 15.4 Stomach in situ Round lig. of liver lesser curvature as the lesser omentum and inferiorly from its greater curvature as the greater omentum. Stomach, body Lesser omentum Spleen Lesser curvature Hepatogastric lig. Right kidney Greater curvature Right colic flexure Descending colon Transversus abdominis, internal and external oblique Ascending colon Duodenum Pyloric canal Pyloric antrum Greater omentum Clinical box 15.1 Gastritis and gastric ulcers Gastritis and gastric ulcers, the two most common diseases of the stomach, are associated with increased acid production and are caused by alcohol, drugs such as aspirin, and the bacterium Helicobacter pylori. Symptoms include lessened appetite, pain, and even bleeding, which manifests as black stool or dark brown material, often described as resembling “coffee grounds,” in vomit. Gastritis is limited to the inner surface of the stomach, whereas gastric ulcers extend into the stomach wall. In these endoscopic images, the gastric ulcer in C is covered with fibrin and shows hematin spots. Gastric ulcer Gastric antrum Rugal folds A Body of normal stomach. B Normal pyloric antrum. C Gastric ulcer. 167 Abdomen Duodenum The small intestine consists of the duodenum, jejunum, and ileum. The duodenum is primarily retroperitoneal and is divided into four parts: superior, descending, horizontal, and ascending. Fig. 15.6 Parts of the duodenum Fig. 15.5 Duodenum: Location Anterior view. Anterior view. RUQ LUQ Esophagus Inferior vena cava Diaphragm, right crus Duodenal bulb Superior (1st) part Duodenojejunal flexure Duodenum Diaphragm, left crus Celiac trunk Superior duodenal flexure Jejunum and ileum Suspensory lig. of duodenum Descending (2nd) part Superior mesenteric a. Jejunum Inferior duodenal flexure Ascending (4th) part Horizontal (3rd) part Fig. 15.7 Duodenum Anterior view with the anterior wall opened. Pyloric orifice Bile duct Pyloric sphincter Duodenum, superior part Circular folds (valves of Kerckring) Accessory pancreatic duct Pancreas Minor duodenal papilla Duodenum, descending part Duodenojejunal flexure Main pancreatic duct Major duodenal papilla Muscular coat 168 Superior mesenteric a. and v. Longitudinal layer Circular layer Jejunum Submucosa Duodenum, horizontal part Fig. 15.8 Duodenum in situ Parietal peritoneum Inferior vena cava Hepatic vv. Common hepatic a. Esophagus Phrenicosplenic lig. Diaphragm Spleen Left gastric a. Hepatic surface of diaphragm Hepatoduodenal lig. (with portal triad) Left suprarenal gland Right suprarenal gland Abdominal aorta Pancreas 15 Internal Organs Anterior view. Removed: Stomach, liver, small intestine, and large ­portions of the transverse colon. Thinned: Retroperitoneal fat and ­connective tissue. Splenic a. Right kidney Left colic flexure Duodenum, superior part Left kidney Superior duodenal recess Right colic flexure Jejunum Transverse colon Superior mesenteric a. and v. Ascending colon Descending colon Inferior duodenal recess Duodenum, descending part Right colic a. Root of mesentery Duodenum, horizontal part Duodenum, ascending part Left colic a. and v. Clinical box 15.2 Endoscopy of the papillary region Two important ducts end at a common exit site in the descending portion of the duodenum: the common bile duct and the pancreatic duct (see Fig. 15.27). These ducts may be examined by X-ray through endoscopic retrograde cholangiopancreatography (ERCP), in which dye is injected endoscopically into the duodenal papilla. Duodenal diverticula (generally harmless outpouchings) may complicate the procedure. Stomach Circular folds Duodenal papilla A Endoscopic appearance. Duodenal diverticula B Radiograph. 169 Abdomen Jejunum & Ileum Fig. 15.9 Jejunum and ileum: Location Anterior view. The intraperitoneal jejunum and ileum are enclosed by the mesentery proper. RUQ Fig. 15.10 Mucosal appearance of the jejunum and ileum Macroscopic views of the longitudinally opened small intestine. Lymphatic follicles (Peyer’s patches) LUQ Duodenojejunal flexure Circular folds Jejunum and ileum RLQ LLQ Rectum Fig. 15.11 Jejunum and ileum in situ Anterior view. Reflected: Transverse colon. A Jejunum. Greater omentum Epiploic (reflected superiorly) appendices B Ileum. Tenia coli Transverse colon Round lig. of liver Transverse mesocolon (with middle colic a. and v.) Jejunum Ascending colon Tenia coli Transversus abdominis, internal and external oblique Cecum Ileum Lateral umbilical fold (with inferior epigastric a. and v.) Rectus abdominis Medial umbilical fold (with obliterated umbilical a.) Median umbilical fold Arcuate (with obliterated urachus) line 170 Clinical box 15.3 15 Internal Organs Crohn’s disease Crohn’s disease, a chronic inflammation of the digestive tract, occurs most often in the terminal ileum (30% of cases). Patients are generally young and suffer from abdominal pain, nausea, elevated body temperature, and diarrhea. Initially, these symptoms can be confused with appendicitis. Complications of the chronic inflammation in Crohn’s disease often lead to fistula formation (seen here in figure B as an abnormal passage between two gastrointestinal regions). A MRI showing thickened wall of terminal ileum. (arrow). Fig. 15.12 Mesentery of the small intestine Liver, right lobe Anterior view. Removed: Stomach, jejunum, and ileum. Reflected: Liver. Round lig. of liver Hepatogastric lig. B Double-contrast radiograph, showing ileorectal fistula (arrow). Liver, left lobe Esophagus Gallbladder Lesser omentum, hepatoduodenal lig. Omental foramen Duodenum, superior part Spleen Gastrosplenic lig. Pancreas Transverse mesocolon, root Stomach, pyloric part Left colic flexure Greater omentum Transverse colon Right colic flexure Duodenojejunal flexure Transverse colon Duodenum, horizontal part Mesentery (cut edge) Descending colon Tenia coli Ascending colon Terminal ileum Cecum Sigmoid mesocolon (cut edge) Rectum 171 Abdomen Cecum, Appendix & Colon The ascending and descending colon are normally secondarily retroperitoneal, but are sometimes suspended by a short mesentery from the posterior abdominal wall. Note: In the clinical setting, the left colic flexure is often referred to as the splenic flexure and the right colic flexure, as the hepatic flexure. Fig. 15.13 Large intestine: Location RUQ Fig. 15.14 Ileocecal orifice Anterior view of longitudinal coronal section. LUQ Anterior view. Left colic flexure Right colic flexure Transverse colon Ascending colon Inner circular layer Outer longitudinal layer Ascending colon Ileal papilla, ileocolic labrum Descending colon Superior lip Inferior lip Sigmoid colon Cecum RLQ Rectum Fig. 15.15 Large intestine Ileocecal orifice LLQ Greater omentum (cut) Anterior view. Haustra Left colic (splenic) flexure Transverse mesocolon Right colic (hepatic) flexure Descending colon Tenia coli Ascending colon Transverse colon Mesentery (with anterior cecal a.) Ileocecal orifice Ileum, terminal part Tenia coli Tenia coli Haustra Tenia coli Sigmoid mesocolon Semilunar folds Iliocecal labrum, superior and inferior lips Cecum Epiploic appendices Vermiform appendix (with orifice) Mesoappendix (with appendicular a.) Rectum (with peritoneal reflection) 172 Muscular coat Sigmoid colon Fig. 15.16 Large intestine in situ Anterior view. Reflected: Transverse colon and greater omentum. Removed: Intraperitoneal small intestine. Transverse colon Left colic (splenic) flexure Transverse mesocolon 15 Internal Organs Greater omentum Duodenojejunal flexure Right colic (hepatic) flexure Descending colon Mesentery (cut) Sigmoid mesocolon Ascending colon Sigmoid colon Terminal ileum Cecum Rectum Rectus abdominis Clinical box 15.4 Clinical box 15.5 Colitis Ulcerative colitis is a chronic inflammation of the large intestine, often starting in the rectum. Typical symptoms include diarrhea (sometimes with blood), pain, weight loss, and inflammation of other organs. Patients are also at higher risk for colorectal carcinomas. A C olonoscopy of ulcerative colitis. B Early-phase colitis. Doublecontrast radiograph, anterior view. Colon carcinoma Malignant tumors of the colon and rectum are among the most frequent solid tumors. More than 90% occur in patients over the age of 50. In early stages, the tumor may be asymptomatic; later symptoms include loss of appetite, changes in bowel movements, and weight loss. Blood in the stools is particularly incriminating, necessitating a thorough examination. Hemorrhoids are not a sufficient explanation for blood in stools unless all other tests (including a colonoscopy) are negative. Colonoscopy of colon carcinoma. The tumor (black arrows) partially blocks the ­lumen of the colon. 173 Abdomen Liver: Overview Fig. 15.17 Liver: Location Spleen RUQ LUQ Stomach Liver Spleen Duodenum Transverse colon Descending colon Ascending colon Small intestine LUQ RUQ Left kidney and suprarenal gland Liver Right kidney and suprarenal gland Pancreas Ascending colon Posterior view. B A Anterior view. Fig. 15.18 Relations of the liver Lesser omentum Visceral (inferior) surface, inferior view. Stomach Pancreas Omental bursa, vestibule Omental bursa, splenic recess Liver Suprarenal impression Spleen Renal impression Inferior Abdominal vena cava aorta Left kidney Transverse section, inferior view. C Gastric impression Fig. 15.19 Liver in situ Diaphragmatic pleura Anterior view. The liver is intraperitoneal except for its “bare area” (see Fig. 15.21); its mesenteries include the falciform, coronary, and triangular ligaments (see Fig. 15.22). Diaphragm Esophagus Duodenal impression Aorta Colic impression Fibrous pericardium Mediastinal pleura Falciform lig. Liver, right lobe Liver, left lobe Stomach Gallbladder 174 Round lig. of liver Transversus abdominis, internal and external oblique Transverse colon Ascending colon Greater omentum Fig. 15.20 Liver in situ: Inferior surface The liver is retracted to show the gallbladder on its inferior surface. Liver, right lobe Falciform lig. of liver Liver, left lobe Lesser omentum Hepatoduodenal lig. Stomach, body 15 Internal Organs Gallbladder Hepatogastric lig. Right kidney Right colic flexure Duodenum Fig. 15.21 Attachment of liver to diaphragm Left triangular lig. Parietal peritoneum Bare area Inferior vena cava Abdominal aorta Coronary lig. Hepatic surface of diaphragm (no parietal peritoneum) Right suprarenal gland Right triangular lig. A Diaphragmatic surface of the liver, ­posterior view. Right kidney Stomach Spleen Hepatoduodenal lig. Pancreas Duodenum B Hepatic surface of the diaphragm, anterior view. Clinical box 15.6 Hepatic cirrhosis Hepatic cirrhosis is a condition leading to irreversible fibrosis of the liver parenchyma. Alcohol abuse is the leading cause (70% of cases) followed by hepatitis B. Portal hypertension with the development of collateral vessels is a common result arising in approximately 30% of cases. AT2W sequence. (Reproduced from Krombach GA, Mahnken AH. Body ­Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) Changes associated with advanced hepatic cirrhosis. All three sequences show multiple regenerating nodules in the liver, creating a nodular surface contour. Only the caudate lobe (B, arrow) is less affected by the changes and still shows a relatively normal signal. B T1W sequence. (Reproduced from Krombach GA, Mahnken AH. Body ­Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) C Fat-suppressed T1W sequence. (Reproduced from Krombach GA, Mahnken AH. Body ­Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) 175 Abdomen Liver: Lobes & Segments Fig. 15.22 Surfaces of the liver divides the liver into right and left anatomical lobes. The round ligament of the liver is found in the free edge of the falciform ligament and is the obliterated umbilical vein, which once extended from the umbilicus to the liver. The liver is divided into four lobes by its ligaments: right, left, caudate, and quadrate. The falciform ligament, a double layer of parietal peritoneum that reflects off the anterior abdominal wall and extends to the liver, spreading out over its surface as visceral peritoneum, Bare area (diaphragmatic surface of liver) Coronary lig. Right triangular lig. Left triangular lig. Fibrous appendix of liver Left lobe, diaphragmatic surface Right lobe, diaphragmatic surface Falciform lig. Round lig. of liver (ligamentum teres hepatis) Inferior border Gallbladder, fundus A Anterior view. Caudate lobe Fibrous appendix of liver Inferior vena cava Lig. of vena cava Bare area Caudate process Coronary lig. Right lobe, visceral surface Left lobe, visceral surface Portal v. Left hepatic duct Right hepatic a. Left hepatic a. Right hepatic duct Proper hepatic a. Round lig. of liver (ligamentum teres hepatis) B Inferior view. 176 Cystic a. Quadrate lobe Bile duct Cystic duct Gallbladder Left and intermediate Groove for hepatic vv. inferior vena cava Left triangular lig. Right hepatic v. 15 Internal Organs Coronary lig. Fibrous appendix of liver Caudate lobe Bare area Ligamentum venosum Left lobe, visceral surface Caudate process Portal v. Right hepatic duct Left hepatic a. Right triangular lig. Round lig. of liver Branch of cystic a. Cystic duct Proper hepatic a. Bile duct Quadrate lobe Right hepatic a. Gallbladder C Posterior view. Right lobe, visceral surface IV II VIII Fig. 15.23 Segmentation of the liver The liver is divided into functional divisions, which are further divided into segments (see Table 15.1). Each segment is served by tertiary branches of the hepatic artery, the portal vein, and the common hepatic duct, which together make up the portal triad. VII III VI Round lig. of liver V Fibrous appendix A Diaphragmatic surface, anterior view. I VII Inferior vena cava II VI III V B Visceral surface, inferior view. Table 15.1 Branches of hepatic vv. Branches of portal v. Branches of proper hepatic a. Branches of hepatic duct Part Left part Round lig. of liver IV Gallbladder Hepatic segments Division Segment Posterior part I Caudate lobe II Left posterolateral III Left anterolateral IV Left medial V Right anteromedial Left lateral division Left medial division Right medial division Right part Right lateral division VI Right anterolateral VII Right posterolateral VIII Right posteromedial 177 Abdomen Gallbladder & Bile Ducts Fig. 15.24 Gallbladder: Location Fig. 15.25 Hepatic bile ducts: Location Projection onto surface of the liver, anterior view. Right duct of caudate lobe RUQ Right hepatic duct Cystic duct Gallbladder Left hepatic duct Right hepatic duct Common hepatic duct Common hepatic duct Bile duct Left duct of caudate lobe Liver, left lobe Cystic duct Liver, right lobe Left hepatic duct A Anterior view. Bile duct Bare area Liver, caudate lobe Inferior vena cava Portal v. Liver, left lobe Right hepatic duct Left hepatic duct Common hepatic duct Bile duct Liver, quadrate lobe Cystic duct Gallbladder B Inferior view. Fig. 15.26 Biliary sphincter system Fig. 15.27 Extrahepatic bile ducts Anterior view. Opened: Gallbladder and duodenum. Sphincter of bile duct Duodenum wall Hepatopancreatic ampulla Gallbladder Sphincter of pancreatic duct Left hepatic duct Cystic duct Common hepatic duct Neck Sphincter of hepatopancreatic ampulla A Sphincters of the pancreatic and bile ducts. Right hepatic duct Infundibulum Gallbladder Duodenum, superior part Body Bile duct Bile duct Fundus Sphincter of hepatopancreatic ampulla Longitudinal slips of duodenal muscle on bile duct Pancreatic duct B Sphincter system in the duodenal wall. 178 Minor duodenal papilla Accessory pancreatic duct Pancreatic duct Major duodenal papilla Duodenum, descending part Duodenum, horizontal part Fig. 15.28 Biliary tract in situ Inferior vena cava Hepatic vv. Esophagus Abdominal aorta Spleen Liver, right lobe Left suprarenal gland Left hepatic duct Right hepatic duct 15 Internal Organs Anterior view. Removed: Stomach, small intestine, transverse colon, and large portions of the liver. The gallbladder is intraperitoneal, covered by visceral peritoneum where it is not attached to the liver. Celiac trunk Common hepatic duct Splenic a. Cystic duct Common hepatic a. Proper hepatic a. Gallbladder Left colic flexure Bile duct Pancreas Right colic flexure Left kidney Hepatopancreatic duct (opening on major duodenal papilla) Jejunum Duodenum, descending part Pancreatic duct Duodenum, ascending part Superior mesenteric a. and v. Clinical box 15.7 Obstruction of the bile duct Fig. 15.29 MR Cholangiopancreatography (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional ­Anatomy, Vol 2, 3rd ed. New York, NY: Thieme; 2007.) Right hepatic duct Left hepatic duct Cystic duct (spiral fold) Common hepatic duct Body of gallbladder Pancreatic duct Neck of gallbladder Common bile duct Duodenum As bile is stored and concentrated in the gallbladder, certain substances, such as cholesterol, may crystallize, resulting in the formation of gallstones. Migration of gallstones into the bile duct causes severe pain (colic). Gallstones may also block the pancreatic duct in the papillary regions, causing highly acute or even life-threatening pancreatitis. Gallstones Duodenal papilla Ultrasound appearance of two gallstones. Black arrows mark the echo-free area behind the stones. 179 Abdomen Pancreas & Spleen Fig. 15.30 Pancreas and spleen: Location RUQ Stomach LUQ Omental bursa, splenic recess Pancreas 10th rib Splenorenal lig. Spleen Liver Spleen Pancreas Gastrosplenic lig. Lesser omentum (hepatogastric lig.) Inferior vena cava B Left lateral view. A Anterior view. Duodenum, superior part Accessory pancreatic duct Pancreas, neck Pancreatic duct Abdominal aorta Left kidney C Transverse section through L1 vertebra, inferior view. Fig. 15.31 Pancreas Anterior view with dissection of the pancreatic duct. Pancreas, body Duodenum, descending part Pancreas, tail Superior mesenteric a. and v. Jejunum Pancreatic duct Duodenum, Pancreas, horizontal part head Pancreas, uncinate process Fig. 15.32 Spleen Duodenum, ascending part Posterior extremity Posterior extremity Superior border Gastric surface Hilum Superior border Splenic a. Splenic v. Renal surface Inferior border A Costal surface. 180 Anterior extremity Diaphragmatic surface Inferior border Colic surface B Visceral surface. Anterior extremity Fig. 15.33 Pancreas and spleen in situ Parietal peritoneum Inferior vena cava Hepatic vv. Left Common Celiac hepatic a. gastric a. trunk Diaphragm Left suprarenal gland Superior border Gastric surface Spleen Hepatic surface of diaphragm Right suprarenal gland 15 Internal Organs Anterior view. Removed: Liver, stomach, small intestine, and large intestine. The pancreas is retroperitoneal, whereas the spleen is intraperitoneal. Splenic a. and v. Hepatoduodenal lig. Pancreas, tail Right kidney Left colic flexure Pancreas, body Transverse mesocolon, root Duodenum, superior part Pancreas, head Left kidney Jejunum Duodenum, descending part Descending colon Left colic a. and v. Duodenum, horizontal part Fig. 15.34 Pancreas and spleen: Transverse section Superior view. Section through L1 vertebra. Inferior vena cava Pancreas, head Mesentery (root) Pancreas, uncinate process Spinal cord (in vertebral L1 canal) vertebra Duodenum, Superior mesenteric ascending part a. and v. Abdominal aorta Splenic a. and v. Right kidney Left kidney and perirenal fat Spleen Parietal peritoneum cut edge Pancreas, tail Right (hepatic) colic flexure Gastrosplenic lig. Omental (epiploic) foramen Duodenum Transverse colon Stomach Portal vein Bile duct Proper hepatic a. Portal triad Lesser omentum (hepatoduodenal and hepatogastric ligs.) Omental bursa (lesser sac) Greater omentum Visceral peritoneum (cut edge) 181 Abdomen Kidneys & Suprarenal Glands (I) Fig. 15.35 Kidneys and suprarenal glands: Location RUQ LUQ 12th rib Right suprarenal gland Subcostal n. Right kidney Iliohypogastric n. Right kidney Left ureter Ilioinguinal n. Iliac crest Urinary bladder B Posterior view. Right side windowed. A Anterior view. Right suprarenal gland Left suprarenal gland Fig. 15.36 Relations of the kidneys: areas of organ contact. Gastric surface Anterior view. Splenic surface Hepatic surface Pancreatic surface Right renal hilum Descending colic surface Right colic flexure surface Fig. 15.37 Right kidney in the renal bed Duodenal surface Right lung Right ureter Left ureter Left renal hilum Diaphragm Perirenal fat capsule Right suprarenal gland Right kidney Renal hilum Renal fibrous capsule Liver Hepatorenal recess Abdominal Inferior aorta vena cava Parietal peritoneum Renal fascia, anterior layer Renal fascia, anterior layer Parietal peritoneum Liver Duodenum Right kidney Fat capsule Renal fascia, posterior layer Iliac crest Renal fascia, posterior layer Transverse colon L 1 vertebra ASagittal section at approximately the level of the renal hilum, viewed from the right side. 182 BTransverse section through the abdomen at approximately the L1/L2 level, viewed from above. Fig. 15.38 Kidneys and suprarenal glands in the retroperitoneum Inferior Proper Portal v. Hepatic vv. vena cava Esophagus hepatic a. Splenic fossa Costodiaphragmatic recess Hepatoduodenal lig. Left gastric a. Right suprarenal gland Left suprarenal gland Hepatic ducts 15 Internal Organs Anterior view. Both the kidneys and ­suprarenal glands are retroperitoneal. Diaphragm, hepatic surface Splenic a. Right kidney Pancreas Duodenum, superior part Transverse mesocolon, root Parietal peritoneum Left renal a. and v. Left kidney Attachment of descending colon Superior mesenteric a. and v. Attachment of ascending colon Duodenum, horizontal part Mesentery, root Abdominal aorta Duodenum, ascending part Left colic a. and v. A Removed: Intraperitoneal organs, along with portions of the ascending and descending colon. Diaphragm Inferior vena cava Esophagus Right superior suprarenal a. Left superior suprarenal a. Abdominal aorta Left suprarenal gland Right suprarenal gland Celiac trunk Left middle and inferior suprarenal aa. Right suprarenal v. Superior mesenteric a. Left suprarenal v. Right inferior suprarenal a. Left renal a. and v. Right renal a. and v. Left ovarian/testicular a. and v. Right kidney Left ureter Perirenal fat capsule Right ureter Iliohypogastric n. Right ovarian/ testicular a. and v. Ilioinguinal n. Inferior mesenteric a. B Removed: Peritoneum, spleen and gastro­intestinal organs, along with fat capsule (left side) Retracted: Esophagus 183 Abdomen Kidneys & Suprarenal Glands (II) Fig. 15.39 Kidney: Structure Right kidney with suprarenal gland. Pararenal fat pad Right suprarenal gland Right suprarenal gland Superior suprarenal aa. Superior pole Middle suprarenal a. Right suprarenal v. Anterior surface Inferior suprarenal a. Renal cortex Medial border Fibrous capsule Right renal a. and v. Lateral border Renal hilum Renal hilum Renal pelvis Posterior surface Right ureter Inferior pole B Posterior view. Anterior view. A Renal cortex Renal pyramid Renal papilla Minor calyx Major calyx Renal a. and v. Renal pelvis Ureter C Posterior view with upper half partially removed. 184 Renal medulla Medullary rays Arcuate a. and v. Interlobar a. and v. Renal column Fibrous capsule Renal papilla Renal cortex Major calyx Segmental aa. and v v. Renal sinus Renal a. and v. Renal pelvis Ureter DPosterior view, midsagittal section. Medullary rays Renal pyramid Fibrous capsule Renal column Minor calyx Fig. 15.40 Right kidney and suprarenal gland Anterior view. Removed: Perirenal fat capsule. Retracted: Inferior vena cava. Inferior vena cava Inferior phrenic a. and v. Suprarenal v. Superior suprarenal aa. Middle suprarenal a. 15 Internal Organs Diaphragm Celiac trunk Right suprarenal gland Abdominal aorta Inferior suprarenal a. Superior mesenteric a. Subcostal n. (12th intercostal n.) Left renal v. Right kidney Right renal a. and v. Right ureter Iliohypogastric n. Right testicular/ ovarian a. and v. Ilioinguinal n. Fig. 15.41 Left kidney and suprarenal gland Anterior view. Removed: Perirenal fat capsule. Retracted: Pancreas. Esophagus Superior suprarenal aa. Left suprarenal gland Inferior phrenic v. Inferior vena cava Diaphragm Inferior phrenic a. Anastomosis between inferior phrenic v. and suprarenal v. Abdominal aorta Portal v. Left gastric a. Middle suprarenal a. Proper hepatic a. Left suprarenal v. Common hepatic a. Subcostal n. Bile duct Pancreas, tail Splenic a. and v. Inferior suprarenal a. Left renal a. and v. Pancreas, neck Superior mesenteric a. and v. Left kidney Transversus abdominis, internal and external oblique Duodenum Left testicular/ ovarian a. and v. Genitofemoral n. Left ureter Ilioinguinal n. Iliohypogastric n. 185 16 Neurovasculature Abdomen Arteries of the Abdominal Wall & Organs Fig 16.1 Arteries of the ­abdominal wall In addition to thoracic and abdominal aortic branches, the abdominal wall is supplied by branches of the subclavian, external iliac and femoral arteries. Numerous potential anastomoses exist between these vessels, which allows the potential for blood to bypass the abdominal aorta. Superior thoracic a. Subclavian a. Axillary a. Lateral thoracic a. Subclavian artery Internal thoracic a. Aortic arch Internal thoracic a. Posterior intercostal aa. Anterior intercostal aa. Thoraco­ dorsal a. Superior epigastric a. Inferior epigastric a. Superficial epigastric a. Thoracic aorta Musculophrenic a. Deep circumflex iliac a. External iliac a. Abdominal aorta Superficial circumflex iliac a. Femoral a. A Anterior view. Superior epigastric a. Subcostal a. 1st–4th lumbar aa. Fig. 16.2 Abdominal aorta and major branches Inferior epigastric a. Anterior view. The abdominal aorta extends from T12 to its bifurcation at L4. It gives off visceral branches to the kidneys, suprarenal glands, gonads, and organs of the gas­ trointestinal system, and parietal branches to the body wall. External iliac a. Femoral a. Superior mesenteric a. (L1) Renal aa. (L1/L2) Inferior mesenteric a. (L3) Left common iliac a. Aortic bifurcation (L4) Right inferior phrenic a. Celiac trunk Left inferior phrenic a. Right superior suprarenal a. Left superior suprarenal a. Common hepatic a. Left gastric a. Table 16.1 Branches of the abdominal aorta The abdominal aorta gives rise to three major unpaired trunks (bold) and the unpaired median sacral artery, as well as six paired branches. Branch from abdominal aorta Branches Inferior phrenic aa. (paired) Superior suprarenal aa. Splenic a. Right gastric a. Left middle suprarenal a. Proper hepatic a. Gastroduodenal a. Left inferior suprarenal a. Superior mesenteric a. Left gastric a. Splenic a. Celiac trunk Left renal a. Common hepatic a. Proper hepatic a. Right gastric a. Gastroduodenal a. Middle suprarenal aa. (paired) Right lumbar a. Left testicular/ ovarian a. Inferior mesenteric a. Superior mesenteric a. Renal aa. (paired) Inferior suprarenal aa. Lumbar aa. (1st through 4th, paired) Left common iliac a. Right common illiac a. Testicular/ovarian aa. (paired) Inferior mesenteric a. Common iliac aa. (paired) Median sacral a. 186 B Lateral view. Celiac trunk (T12) Median sacral a. External iliac a. Internal iliac a. Common hepatic a. Fig. 16.3 Celiac trunk Abdominal aorta Celiac trunk Splenic a. Splenic a. with pancreatic brs. Left gastric a. Common hepatic a. Proper hepatic a. Left gastric a. Gastroduodenal a. A. of pan­ creatic tail Gastro­ duodenal a. Great pancreatic a. Left gastro­ Posterior superior pancreatico­ omental a. duodenal a. Pancreatic Anterior superior brs. pancreatico­ Right gastro­ duodenal a. omental a. Right gastric a. Anterior/posterior superior pancreatico­ duodenal a. Duodenal br. Inferior pancreatico­ duodenal a. Superior mesenteric a. A Celiac trunk distribution. Inferior pancreatic a. Dorsal pancreatic a. Inferior pancreatico­ duodenal a., anterior br. Superior mesenteric a. Arterial supply to the pancreas B Fig. 16.5 Inferior mesenteric artery Fig. 16.4 Superior mesenteric artery Inferior pancreatico­ duodenal a. 16 Neurovasculature Abdominal aorta Celiac trunk Inferior mesenteric a. Left colic aa. Left colic flexure Superior mesenteric a. Left colic flexure Middle colic a. Right colic a. Ileocolic a. Jejunal and ileal aa. Appendicular a. Fig. 16.6 Abdominal arterial anastomoses Three major anastomoses provide overlap in the arterial supply to abdominal areas to ensure adequate blood flow. Between the: 1–celiac trunk and the superior mesenteric artery via the pan­ creaticoduodenal arteries. 2–superior and inferior mesenteric arteries via the middle and left colic arteries. 3–inferior mesenteric and the internal iliac arteries via the superior and middle or inferior rectal arteries. Superior rectal a. Celiac trunk supplies: Esophagus Stomach Duodenum Liver Spleen Gallbladder Pancreas Superior mesenteric a. supplies: Pancreas Duodenum Jejunum Ileum Cecum Ascending and transverse colon Inferior mesenteric a. supplies: Transverse, descending and sigmoid colon Rectum Anal canal Sigmoid aa. Pancreatico­ duodenal aa. 1 Middle colic a. 2 Left colic a. 3 Superior rectal a. Middle/inferior rectal a. Internal iliac a. supplies: reproductive organs 187 Abdomen Abdominal Aorta & Renal Arteries Fig. 16.7 Abdominal aorta Anterior view of the female abdomen. Removed: All organs except the left kidney and suprarenal gland. The abdominal aorta is the distal continuation of the thoracic aorta (see p. 80). It enters the abdomen at the T12 level through the aortic hiatus and courses anterior to the vertebral bodies to the left of the midline before bifurcating into the common iliac arteries at L4. Esophagus Inferior vena cava Left superior suprarenal aa. Left inferior phrenic a. Aortic hiatus (median arcuate lig.) Left middle suprarenal a. Celiac trunk Left inferior suprarenal a. Superior mesenteric a. Left renal a. Left 1st lumbar a. Abdominal aorta Inferior mesenteric a. Left ovarian a. (testicular a. in males) Right common iliac a. Left ureter Median sacral a. Left iliolumbar a. Right internal iliac a. Left superior gluteal a. Right external iliac a. Left lateral sacral a. Right umbilical a. Sacral plexus Right obturator a. Left deep circumflex iliac a. Right inferior vesical a. Left inferior epigastric a. Right superior vesical a. Femoral a. and v. Uterine a. Obturator branch of right inferior epigastric a. 188 Right middle rectal a. Right inferior gluteal a. Right internal pudendal a. Fig. 16.8 Renal arteries Medullary (renal) pyramid Arcuate a. (at base of medullary pyramids) Minor calyx Major calyx Superior segmental a. Anterior superior segmental a. Capsular brs. 16 Neurovasculature Left kidney, anterior view. The renal arteries arise at approximately L1/L2. Each artery divides into an anterior and a posterior branch. The anterior Interlobar a. branch further divides into four seg­ (between the mental arteries (circled). medullary pyramids) Interlobular a. Inferior suprarenal a. Fibrous capsule Left renal a., main trunk Branch of posterior segmental a. Left renal a., anterior br. Anterior inferior segmental a. Left renal a., posterior br. Renal pelvis Inferior segmental a. Ureteral brs. Left ureter Clinical box 16.1 Clinical box 16.2 Variants of the renal artery Anterior view of the right kidney. As the kidneys ascend from their site of origin in the pelvis to the lumbar region, new renal arteries are formed as older ones regress. Commonly some fail to regress, resulting in multiple arteries to one or both kidneys. Abdominal aorta Aberrant right renal a. Abdominal aorta Renal hypertension The kidney is an important blood pressure sensor and regulator. Stenosis (narrowing) of the renal artery reduces blood flow through the kidney and stimulates increased production of renin, an enzyme that cleaves angiotensinogen to form angiotensin I. Subsequent cleavage yields angiotensin II, which induces vasoconstriction and an increase in blood pressure. Renal hypertension should be excluded (or confirmed) when diagnosing high blood pressure. Accessory renal a. behind inferior vena cava Accessory renal a. in front of inferior vena cava Inferior vena cava A Accessory renal arteries pass from the aorta to the renal h ­ ilum. Note: one of the ­accessory arteries is passing anterior to the inferior vena cava. Inferior vena cava B Aberrant renal arteries do not enter the kidney at the hilum. Stenosis of the right renal artery (arrow), visible via arteriography. 189 Abdomen Celiac Trunk Fig. 16.9 Celiac trunk: Stomach, liver, and gallbladder Anterior view. Opened: Lesser omentum. Incised: Greater omentum. The celiac trunk arises from the abdominal aorta at about the level of T12. It supplies the structures of the foregut, the proximal part of the alimentary canal and the spleen. The foregut consists of the esophagus (distal 1.25 cm), stomach, duodenum (proximal half), liver, gallbladder, and pancreas (superior portion). Abdominal aorta Left hepatic a. Right hepatic a. Inferior vena cava Left gastric a. Lesser omentum Liver Stomach Spleen Gallbladder Cystic a. Proper hepatic a. Portal v. Celiac trunk Common hepatic a. Bile duct Gastro­ duodenal a. Right gastric a. Posterior superior pancreatico­ duodenal a. Gastro­ duodenal a. Duodenum Anterior superior pancreaticoduodenal a. 190 Right gastro­ omental a. Splenic a. Pancreas Left gastro­ omental a. Greater omentum 16 Neurovasculature Fig. 16.10 Celiac trunk: Pancreas, duodenum, and spleen Anterior view. Removed: Stomach (body) and lesser omentum. Inferior vena cava Common hepatic a. Left gastric a. Celiac trunk Splenic a. Posterior gastric a. Short gastric aa. Cystic a. Proper hepatic a. Portal v. Right gastric a. Gastro­ duodenal a. Splenic v. Left gastro­ omental a. A. of pancre­ atic tail Supra­ duodenal a. (variant) Splenic a., pancreatic brs. Posterior superior pancreatico­ duodenal a. Great pancreatic a. Anterior superior pancreatico­ duodenal a. Inferior pancreatic a. Duodenal br. Right gastro­ omental a. Inferior pancreatico­ duodenal a. Posterior br. Anterior br. Superior mesenteric a. and v. Inferior pancreatico­ duodenal a. Dorsal pancreatic a. Transverse mesocolon, root Anastomosis between superior mesenteric a. and inferior pancreatic a. 191 Abdomen Superior & Inferior Mesenteric Arteries Fig. 16.11 Superior mesenteric artery Anterior view. Partially removed: Stomach, duodenum, and peritoneum. Reflected: Liver and gallbladder. Note: The middle colic artery has been truncated (see Fig. 16.12). The superior mesenteric artery arises from the aorta opposite L1. It supplies the structures of the midgut: the duodenum (distal half), jejunum and ileum, cecum and appendix, ascending colon, right colic flexure, and the proximal two thirds of the transverse colon. Portal v. Inferior vena cava Proper hepatic a. Right gastric a. Gastroduodenal a. Left gastric a. Common hepatic a. Splenic a. Left renal v. Right gastro­ omental a. Anterior superior pancreatico­ duodenal a. Inferior pancreatico­ duodenal a., anterior and posterior brs. Left renal a. Superior mesenteric a. Middle colic a. (cut) Jejunal aa. Right colic a. Marginal a. Ileocolic a. Ileal aa. Ileocolic a., colic br. Ileocolic a., ileal br. Posterior cecal a. Vasa recta Anterior cecal a. Clinical box 16.3 Mesenteric ischemia A decrease in blood flow to the intestine (ischemia) can result from occlusion of the superior mesenteric artery (SMA) by a thrombus or embolus (acute) or may be secondary to severe atherosclerosis (chronic). In the acute condition, the embolus can obstruct the SMA at its origin or, if small enough, may travel further to obstruct a more peripheral branch. Acute ischemia results in necrosis of the affected part of the intestine. Chronic ischemia is less 192 threatening since obstruction of the vessels occurs gradually, allowing the formation of collateral vessels that will supply the affected intestine. Because of the extensive anastomoses between intestinal arteries, chronic vascular ischemia is rare. Symptoms occur only if two of the three major vessels (celiac trunk or superior or inferior mesenteric arteries) are compromised. Fig. 16.12 Inferior mesenteric artery Anterior view. Removed: Jejunum and ileum. Reflected: Transverse colon. Greater omentum Transverse colon Marginal a. 16 Neurovasculature The inferior mesenteric artery arises from the aorta opposite L3. It supplies structures of the hindgut: the transverse colon (distal third), left colic flexure, descending and sigmoid colons, rectum, and anal canal (upper part). Left colic (splenic) flexure Middle colic a. Superior mesenteric a. (cut) Duodenum Right colic a. Abdominal aorta Descending colon Inferior vena cava Inferior mesenteric a. Ascending colon Marginal a. Left colic a. Right common iliac a. Aortic bifurcation Sigmoid aa. Ileocolic a. (cut) Ileocolic a., colic br. Superior rectal a. Ileocolic a., ileal br. Sigmoid colon Posterior cecal a. Anterior cecal a. Clinical box 16.4 Anatomoses between arteries of the large intestine Anastomoses between branches of the superior mesenteric and inferior mesenteric arteries can compensate for abnormally low blood flow in either of the arteries. Two of these anastomoses, although variable, are of significant value: Riolan’s arcade (arc of Riolan) – a connection between the middle colic artery and the left colic artery that arises close to their origins from the superior and inferior mesenteric arteries, respectively. Middle colic a. Superior mesenteric a. Left colic flexure Marginal a. (of Drummond) Arc of Riolan Inferior mesenteric a. Left colic a. Marginal artery (of Drummond) – a connection between all arteries of the colon that runs along the periphery of the mesentery close to the intestinal tube. 193 Abdomen Veins of the Abdominal Wall & Organs Fig 16.13 Veins of the abdominal wall Subclavian v. The abdominal wall is drained by veins that accompany the arteries and are tributaries of the azygos system and inferior vena cava. Additionally, a large thoracoepigastric vein connects the femoral and axillary veins. Axillary v. Cephalic v. Azygos v. Superior vena cava Areolar venous plexus Internal thoracic v. Posterior intercostal vv. Anterior intercostal vv. Superior epigastric v. Musculophrenic v. Thoracoepigastric v. Periumbilical vv. Superficial epigastric v. A Anterior view. External pu­ dendal vv. Great saphe­ nous v. Superficial circumflex iliac v. Inferior vena cava Subcostal v. Femoral v. Lumbar vv. Fig. 16.14 Inferior vena cava Anterior view. The inferior vena cava arises at L5 with the convergence of the common iliac veins. It ascends along the right side of the vertebral column, passes through the caval opening in the diaphragm at T8 and terminates in the thorax in the right atrium of the heart. Inferior epigastric v. External iliac v. Femoral v. B Lateral view. Inferior vena cava L4 vertebra Abdominal aorta Common iliac vv. Table 16.2 1R 1L ② 3R Tributaries of the inferior vena cava Inferior phrenic vv. (paired) Hepatic vv. (3) 3L Azygos v. Suprarenal vv. (the right vein is a direct tributary) 1R 4R 4L Renal vv. (paired) 5R 5L Testicular/ovarian vv. (the right vein is a direct tributary) 6R 6L Ascending lumbar vv. (paired), not direct tributaries 3R 7R 7L Lumbar vv. 4R 8R 8L Common iliac vv. (paired) ⑨ Median sacral v. Inferior vena cava Hemiazygos v. 1L ② 3L 4L 5L 7R 6L 5R 7L 6R 8R 194 8L ⑨ Fig. 16.15 Portal vein From hepatic vv. within the liver to IVC Left gastric v. (with esophageal vv.) Right gastric v. Short gastric vv. Splenic v. Cystic v. Pancreatic vv. Portal v. Splenic v. Portal v. Posterior superior pancreatico­ duodenal v. Inferior mesen­ teric v. L4 Superior mesen­ teric v. Left gastro­ omental v. 16 Neurovasculature The portal vein (see p. 198) drains venous blood from the abdominopelvic organs sup­ plied by the celiac trunk and superior and inferior mesenteric arteries. Right gastro­ omental v. Inferior pancreatico­ duodenal v. Inferior mesenteric v. Superior mesenteric v. A Location, anterior view. Middle colic v. Left colic v. Right colic v. Ileocolic v. Sigmoid vv. Appendicular v. Subclavian v. Right Left Esophageal gastric v. gastric v. vv. Azygos/ hemi­ azygos v. Superior vena cava A Ileal Jejunal vv. vv. Superior rectal v. B Portal vein distribution. Clinical box 16.5 Internal thoracic v. Portal v. Inferior vena cava Paraumbilical vv. Superior epigastric v. S Common iliac v. Superior mesenteric v. Periumbilical vv. S Inferior mesenteric v. D Colic vv. F Superior rectal v. Inferior epigastric v. Ascending lumbar v. D Colic vv. Middle/inferior rectal v. Cancer metastases Tumors in the region drained by the superior rectal vein may spread through the portal venous system to the capillary bed of the liver (hepatic metastasis). Tumors drained by the middle or inferior rectal veins may metastasize to the capillary bed of the lung (pulmonary metastasis) via the inferior vena cava and right heart. C Portocaval anastomotic collateral pathways between the portal and systemic systems. When the portal system is compromised, the portal vein can divert blood away from the liver back to its supplying veins, which return this nutrientrich blood to the heart via the venae cavae. The red arrows indicate the flow reversal in the (1) esophageal veins, (2) paraumbilical veins, (3) the colic veins, and (4) the middle and infe­ rior rectal veins. 195 Abdomen Inferior Vena Cava & Renal Veins Fig. 16.16 Inferior vena cava Anterior view of the female abdomen. Removed: All organs except the left kidney and suprarenal gland. The inferior vena cava courses along the right side of the vertebral bodies from its origin at L5 to the caval opening in the diaphragm at T8. Unlike the branches of the aorta, vis­ ceral and parietal drainages to the inferior vena cava are asymmetrical (note drainages of the suprarenal glands, gonads and azgygos veins). It communicates with the azygos system through lumbar veins and receives blood from the portal venous system via the hepatic veins. Hepatic vv. Left inferior phrenic v. Esophagus Inferior vena cava Celiac trunk Right suprarenal v. Left suprarenal v. Superior mesenteric a. Left renal a. and v. Left ovarian a. and v. Right renal v. Ureter Right ovarian a. and v. Abdominal aorta Left ascending lumbar v. Left 3rd lumbar v. Inferior mesenteric a. Left common iliac a. and v. Right common iliac v. Deep circumflex iliac a. and v. Left lateral sacral v. Right internal iliac v. Left superior gluteal v. Right external iliac v. Right obturator v. Median sacral a. and v. Right middle rectal v. Right inferior epigastric a. and v. Right internal pudendal v. Rectum (and rectal venous plexus) Uterine venous plexus Right inferior gluteal v. Vesical venous plexus Right uterine v. Right inferior vesical v. Femoral a. and v. 196 Vagina Urethra Fig. 16.17 Renal veins Anterior view. See p. 189 for the renal arteries in isolation. Removed: All organs except kidneys and suprarenal glands. Right inferior phrenic a. and v. Left superior suprarenal aa. Inferior vena cava 16 Neurovasculature Left inferior phrenic v. (anastomosis with left suprarenal v.) Left inferior phrenic a. Right superior suprarenal a. Celiac trunk Right suprarenal v. (typically opens directly into inferior vena cava) Left middle suprarenal a. Left suprarenal v. (typically opens into left renal v.) Right middle suprarenal a. Left inferior suprarenal a. Right inferior suprarenal a. Left renal a. and v. Right renal a. and v. Superior mesenteric a. Right testicular/ ovarian a. and v. Left testicular/ ovarian a. and v. Right ureter Abdominal aorta Ureteral branches (from testicular/ ovarian a. or common iliac a.) Inferior mesenteric a. Clinical box 16.6 Tributaries of the left renal vein On the right side, the suprarenal and testicular/ovarian veins drain directly into the inferior vena cava. The corresponding veins on the left side, however, drain into the left renal vein. (This is a remnant from early development when there were both right and left sided venae cave.) It is believed that this asymmetrical drainage pattern is the cause of the varicose dilations of the veins in the spermatic cord (varicoceles) that occur more commonly on the left side. Right inferior phrenic v. Inferior vena cava Right suprarenal v. Right renal v. Right testicular/ ovarian v. Left inferior phrenic v. Anastomosis Left suprarenal v. Left renal v. Left testicular/ ovarian v. 197 Abdomen Portal Vein Fig. 16.18 Portal vein: Stomach and duodenum Anterior view. Removed: Liver, lesser omentum, and peritoneum. Opened: Greater omentum. The portal vein is typically formed by the Common hepatic a. Inferior vena cava Hepatic vv. union of the superior mesenteric and the splenic veins posterior to the neck of the pancreas. Celiac trunk Esophageal vv. Left and right hepatic aa. Left gastric a. and v. Proper hepatic a. Short gastric vv. Portal v. Spleen Right kidney and supra­ renal gland Splenic a. and v. Gastro­ duodenal a. Posterior superior pancreatico­ duodenal a. Left gastro­ omental a. and v. Anterior superior pancreatico­ duodenal a. Splenic a. Pancreatico­ duodenal v. Greater omentum Inferior pancreatico­ duodenal a. 198 Middle colic v. Superior mesenteric a. and v. Right gastro­ omental a. and v. Right gastric a. and v. Fig. 16.19 Portal vein: Pancreas and spleen Anterior view. Partially removed: Liver, stomach, pancreas, and peritoneum. Short gastric vv. Inferior vena cava Left gastric a. and v. Left and right hepatic aa. 16 Neurovasculature Hepatic vv. Celiac trunk Proper hepatic a. Splenic a. and v. Portal v. Splenic v. Right gastric a. Inferior pancreatic a. Gastro­ duodenal a. Left gastro­ omental a. and v. Right gastric v. Left supra­ renal v. Posterior and anterior superior pancreatico­ duodenal aa. Left renal a. and v. Left ureter Pancreatico­ duodenal v. Inferior pancreatico­ duodenal a., anterior and posterior brs. Middle colic v. Superior mesenteric a. and v. Right gastro­ omental a. and v. Left ovarian/ testicular Inferior a. and v. Left ascending mesenteric v. lumbar v. Clinical box 16.7 Esophageal varices Upper esophageal veins drain into the azygos system, but the lower esophagus drains into the portal system via the left gastric veins. As a result of this portocaval anastomosis, venous varices (dilations, arrows) of the esophageal wall may develop in patients with portal hypertension. Severe acute hemorrhage is the greatest risk associated with this condition. 199 Abdomen Superior & Inferior Mesenteric Veins Fig. 16.20 Superior mesenteric vein Anterior view. Partially removed: Stomach, duodenum, and peritoneum. Removed: Pancreas, greater omentum, and transverse colon. Reflected: Liver and gallbladder. Displaced: Small intestine. The superior mesen­ teric vein receives tributaries from the entire small intestine as well as the cecum, appendix, ascending colon, and two thirds of the transverse colon. It normally lies to the right of the superior mesenteric artery then joins with the splenic vein posterior to the neck of the pancreas to form the portal vein. Left gastric a. and v. Proper hepatic a. Inferior vena cava Portal v. Splenic a. and v. Right gastric a. and v. Left renal a. Inferior mesenteric v. Gastro­ duodenal a. Right gastro­ omental a. and v. Middle colic a. and v. Pancreatico­ duodenal a. and vv. Superior mesenteric a. and v. Right colic a. and v. Inferior vena cava Jejunal aa. and vv. Ileocolic a. and v. Ileocolic a., colic br. Ileal aa. and vv. Cecal vv. Posterior cecal a., appendicular v. 200 Anterior cecal a. Ileocolic a., ileal br. Fig. 16.21 Inferior mesenteric vein Portal v. from the artery, and generally joins with the splenic vein posterior to the stomach and pancreas. Note that the ascending and descending colons may also be drained by lumbar veins in the retroperitoneum, which empty into the inferior vena cava, constituting a portocaval collateral pathway. Inferior vena cava Left gastric a. and v. 16 Neurovasculature Anterior view. Partially removed: Stomach, duodenum, and peritoneum. Removed: Pancreas, greater omentum, transverse colon, and small intestine. Reflected: Liver and gallbladder. The inferior mesenteric vein drains a smaller territory than the superior mesenteric vein. It receives tributaries from the distal transverse colon, descending and sigmoid colons and upper rectum. It ascends in the retroperitoneum, separate Proper hepatic a. Splenic a. and v. Right gastric a. and v. Left renal a. Gastro­ duodenal a. Inferior mesenteric v. Right gastro­ omental a. and v. Middle colic a. and v. Superior mesenteric a. and v. Right colic a. and v. Left colic a. and v. Ileocolic a. and v. Jejunal/ileal aa. and vv. (cut) Inferior mesenteric a. and v. Left common iliac a. and v. Sigmoid aa. and vv. Cecal vv. Posterior cecal a. Anterior cecal a. Superior rectal a. and v. 201 Abdomen Lymphatics of the Abdominal Wall & Organs Fig. 16.22 Lymphatic drainage of the anterior trunk wall Lymph from the skin of the trunk wall is collected mainly by the axil­ lary and superficial inguinal lymph nodes (arrows indicate direction of lymph flow). A curved line that lies between the umbilicus and costal arch defines the “watershed” zone between the two drainages. Lymph from the right upper quadrant (green) is drained by the right lymphatic duct. Lymph from the remainder of the body (blue) is drained by the thoracic duct. Cervical l.n. Axillary l.n. Parasternal l.n. “Watershed” Superficial inguinal l.n. Fig. 16.23 Lymphatic drainage of the internal organs See Table 16.3 for numbering. Lymph drainage from the abdomen, pelvis, and lower limb ultimately passes through the lumbar lymph nodes (clinically, the aortic nodes), which consist of the right lateral aortic (caval) and left lateral aortic nodes, the preaortic nodes, and the retroaortic nodes. Efferent lymph vessels from the lateral aortic, retroaortic, and inferior mesenteric nodes form the lumbar trunks. Those from the remaining preaortic nodes form the intestinal trunks. The lumbar and intestinal trunks terminate in the cisterna chyli. ① Inferior phrenic l.n. ② Celiac l.n. Preaortic l.n. Lumbar l.n. ③ Superior mesenteric l.n. ④ Inferior mesenteric l.n. ⑤ Left lateral aortic l.n. ⑥ Right lateral aortic (caval) l.n. Cisterna chyli Thoracic duct Parietal lymph nodes of the abdomen Table 16.3 ⑦ Retroaortic l.n. Intestinal trunk ⑧ Common iliac l.n. Right lumbar trunk ③ ⑥ Left lumbar trunk ② ② ⑤ ④ ⑧ Right common iliac l.n. ① ⑧ ③ Cisterna chyli Lumbar l.n. ⑦ ⑤ ⑥ ④ Left common iliac l.n. ⑧ 202 Lateral aortic l.n. Preaortic l.n. 16 Neurovasculature Splenic l.n. Left lumbar l.n. Hepatic l.n. Superior mesenteric l.n. Cystic l.n. Foraminal l.n. Juxta­intestinal l.n. Prececal l.n. Retrocecal l.n. Celiac l.n. Ileocolic l.n. Appendicular l.n. Right/left gastric l.n. Mesocolic l.n. Pyloric l.n. Right colic l.n. Supra­, sub­, and retropyloric l.n. Middle colic l.n. Right left gastroomental l.n. Superior/inferior pancreatic l.n. Superior/inferior pancreaticoduodenal l.n. Mesocolic l.n. Left colic l.n. Inferior mesenteric l.n. Sigmoid l.n. Superior rectal l.n. Fig. 16.24 Principal lymphatic pathways draining the digestive organs and spleen Lymph from the spleen and most digestive organs drains directly from regional lymph nodes or through intervening collecting nodes to the intestinal trunks, except for the descending and sigmoid colon and the upper part of the rectum, which are drained by the left lumbar trunk. The three large collecting nodes are: • Celiac lymph nodes collect lymph from the stomach, duodenum, pancreas, spleen, and liver. Topographically and at dissection they are often indistinguishable from the regional lymph nodes of the nearby upper abdominal organs. • Superior mesenteric lymph nodes collect lymph from the jejunum, ileum, ascending and transverse colon. • Inferior mesenteric lymph nodes collect lymph from the descending and sigmoid colon and rectum. These nodes drain principally through the intestinal trunks to the cisterna chyli, but there is an accessory drainage route by way of the left lumbar lymph nodes. Lymph from the pelvis also drains up into the inferior mesenteric and lateral aortic lymph nodes. A complete drainage pathway for lymph from the pelvis can be found on p. 276. 203 Abdomen Lymph Nodes of the Posterior Abdominal Wall Lymph nodes in the abdomen and pelvis may be classified as either pa­ rietal or visceral. The majority of the parietal lymph nodes are located on the posterior abdominal wall. Fig. 16.25 Parietal lymph nodes in the abdomen and pelvis Anterior view. Removed: All visceral structures except vessels. Inferior vena cava Esophagus Diaphragm Celiac l.n. Inferior phrenic l.n. Abdominal aorta Superior mesenteric l.n. Cisterna chyli Right lumbar trunk Retrocaval l.n. Intermediate lumbar l.n. Right lateral caval l.n. Common iliac a. Sacral l.n. Intestinal trunk Left lumbar trunk Retroaortic l.n. Left lateral aortic l.n. Inferior mesenteric l.n. Common iliac l.n. Internal iliac l.n. External iliac l.n. Inguinal lig. Intermediate lacunar l.n. Deep inguinal l.n. 204 Superficial inguinal l.n. (horizontal and vertical groups) 16 Neurovasculature Fig. 16.26 Lymph nodes of the kidneys, ureters, and ­suprarenal glands Anterior view. Inferior phrenic l.n. Retrocaval l.n. Left lateral aortic l.n. Right lateral caval l.n. Preaortic l.n. Intermediate lumbar l.n. Common iliac l.n. Promontory l.n. Fig. 16.27 Lymphatic drainage of the kidneys and gonads (with pelvic organs) Thoracic duct Right lumbar trunk Cisterna chyli Left lumbar trunk Right lumbar l.n. Left lumbar l.n. Lateral caval l.n. Lateral aortic l.n. Intermediate lumbar l.n. Precaval l.n. Preaortic l.n. Retrocaval l.n. Lacunar l.n. (lateral, medial, and intermediate) Deep inguinal l.n. Retroaortic l.n. External iliac l.n. Common iliac l.n. Internal iliac l.n. Obturator l.n. Subaortic l.n. Sacral l.n. Lateral, medial, and intermediate external iliac l.n. Promontory l.n. Superior and inferior gluteal l.n. Interiliac l.n. Lateral, medial, and intermediate common iliac l.n. Superficial inguinal l.n. Lower limb, uterus, and vagina 205 Abdomen Lymph Nodes of the Supracolic Organs Fig. 16.28 Lymph nodes of the stomach and liver Anterior view. Removed: Lesser omentum. Opened: Greater omentum. Arrows show direction of lymphatic drainage. Inferior vena cava Celiac l.n. Cardiac lymphatic ring Left gastric l.n. Splenic l.n. Hepatic l.n. Portal v. Left gastro­ omental l.n. Pancreatic l.n. Suprapyloric l.n. Subpyloric l.n. Right gastro­ omental l.n. Fig. 16.29 Lymphatic drainage of the liver and biliary tract Anterior view. In the region of the liver, the major lymph-producing organ, the important pathways are: • Liver and intrahepatic bile ducts: Most lymph drains inferiorly through the hepatic nodes to the celiac nodes and then to the intestinal trunk and cisterna chyli, but it may take a more direct route bypassing the celiac nodes. A small amount drains cranially through the inferior phrenic nodes to the lumbar trunk. It also can drain through the diaphragm to the superior phrenic nodes and on to the bronchomediastinal trunk. • Gallbladder: Lymph drains initially to the cystic node, then follows one of the pathways described above. • Common bile duct: Lymph drains through the pyloric nodes (supra-, sub-, and retropyloric) and the foraminal node to the celiac nodes, then to the intestinal trunk. 206 Diaphragm Inferior phrenic l.n. Superior phrenic l.n. Liver Hepatic l.n. Inferior vena cava Stomach Cystic l.n. Celiac trunk with celiac l.n. Gallbladder Pancreas Duodenum Pyloric l.n. Bile duct Fig. 16.30 Lymph nodes of the spleen, pancreas, and duodenum Anterior view. Removed: Stomach and colon. 16 Neurovasculature Left gastric l.n. Cystic l.n. Splenic l.n. Hepatic l.n. Celiac l.n. Suprapyloric l.n. Pancreatic l.n. (superior) Retropyloric l.n. Subpyloric l.n. Pancreatic l.n. (inferior) Superior mesenteric l.n. Pancreaticoduodenal l.n. Fig. 16.31 Lymphatic drainage of the stomach, liver, spleen, pancreas, and duodenum Thoracic duct Cisterna chyli Hepatic l.n. Intestinal trunks Splenic l.n. Cystic l.n. Foraminal l.n. Celiac l.n. Superior mesenteric l.n. Pancreatic l.n. (superior and inferior) Pancreaticoduodenal l.n. (superior and inferior) Gastric l.n. (right and left) Pyloric l.n. Supra­, sub­, and retropyloric l.n. Gastro­omental l.n. (right and left) 207 Abdomen Lymph Nodes of the Infracolic Organs Fig. 16.32 Lymph nodes of the jejunum and ileum Anterior view. Removed: Stomach, liver, pancreas, and colon. Abdominal aorta Celiac l.n. Thoracic duct with cisterna chyli Superior mesenteric l.n. Transverse colon Duodenum Ascending colon Jejunum Intermediate mesenteric l.n. Ileocolic l.n. Juxta­intestinal l.n. Ileum Fig. 16.33 Lymphatic drainage of the intestines Thoracic duct Left lumbar l.n. Left lumbar trunk Cisterna chyli Intestinal trunks Lateral aortic l.n. Preaortic l.n. Superior mesenteric l.n. Juxta­intestinal l.n. Inferior mesenteric l.n. Mesocolic l.n. Sigmoid l.n. Left colic l.n. Superior rectal l.n. Middle colic l.n. Right colic l.n. 208 Prececal l.n. Retrocecal l.n. Ileocolic l.n. Appendicular l.n. 16 Neurovasculature Fig. 16.34 Lymph nodes of the large intestine Anterior view. Reflected: Transverse colon and greater omentum. Epicolic l.n. Middle colic l.n. Right colic l.n. Superior mesenteric l.n. Left colic l.n. Paracolic l.n. Inferior mesenteric l.n. Ileocolic l.n. Intermediate colic l.n. Sigmoid l.n. Prececal l.n. Superior rectal l.n. Clinical box 16.8 Lymphatic drainage of the large intestine Regional lymphatic pathways in the large intestine have important clinical affects. • Upper rectum: Lymph drains initially to the superior rectal nodes then fol­ lows the pathway described above for the sigmoid colon. • Ascending colon, cecum, and transverse colon: Lymph drains initially to the right and middle colic nodes, then to the superior mesenteric nodes, and finally to the intestinal trunk. • Descending colon: Lymph drains initially to the regional left colic nodes, then to the inferior mesenteric nodes, then via the left lumbar nodes into the left lumbar trunk. • Sigmoid colon: Lymph drains initially to sigmoid nodes then follows the pathway described above for the descending colon. Thus, a malignant tumor undergoing lymphogenous spread must negotiate several lymph node groups (all of which should be removed in tumor resections) before the malignant cells can reach the intestinal trunk and thoracic duct and finally enter the bloodstream. This long route of lymphogenous spread improves the prospects for a cure. 209 Abdomen Nerves of the Abdominal Wall Fig. 16.35 Somatic nerves of the abdomen and pelvis Anterior view. The abdominal wall is innervated by somatic nerves that include the lower intercostal nerves and branches of the lumbar plexus. Intercostal nn. Intercostal nn. Subcostal n. Lumbar plexus Iliohypogastric n. Ilioinguinal n. Genitofemoral n. Obturator n. Sacral plexus Femoral n. Sciatic n. Fig. 16.36 Cutaneous innervation of the anterior trunk Anterior view. Fig. 16.37 Dermatomes of the anterior trunk Anterior view. C3 Supraclavicular nn. C4 T2 T3 C5 Intercostal nn., lateral cutaneous brs. Iliohypogastric n., lateral cutaneous br. Lateral femoral cutaneous n. Femoral n., anterior cutaneous brs. 210 Intercostal nn., anterior cutaneous brs. Iliohypogastric n., anterior cutaneous br. Genitofemoral n., femoral br. Ilioinguinal n. T4 C6 T1 T 10 L2 T 12 L3 L1 C8 S2 C7 L4 Fig. 16.38 Nerves of the lumbar plexus Anterior view. 16 Neurovasculature Inferior vena cava Lateral arcuate lig. Diaphragm, lumbar part Median arcuate lig. Subcostal n. Medial arcuate lig. Quadratus lumborum Sympathetic trunk Transversus abdominis Abdominal aorta Iliohypogastric n. Ilioinguinal n. Psoas major and minor Genital br. Iliacus Genitofe­ moral n. Femoral br. Iliohypogastric n., lateral cutaneous br. Femoral n. Lateral femoral cutaneous n. Iliohypogastric n., anterior cutaneous br. Ilioinguinal n. Genitofemoral n., femoral br. Genitofemoral n., genital br. Femoral n., anterior cutaneous br. Abdominal aorta Subcostal n. Genitofemoral n. Iliohypogastric n. A Lumbar plexus in situ. Removed: All visceral structures except vessels. Lumbar plexus Ilioinguinal n. Lateral femoral cutaneous n. Obturator n. Femoral n. Sympathetic trunk Inferior vena cava Common iliac a. Internal iliac a. External iliac a. Genitofe­ moral n. Femoral br. Genital br. Lumbar plexus, dissection. B Windowed: Psoas major and minor muscles. 211 Autonomic Innervation: Overview Sympathetic Parasympathetic Sympathetic Abdomen Head and neck Fig. 16.39 Sympathetic and parasympathetic nervous systems in the abdomen and pelvis Superior cervical ganglion Superior cervical ganglion Sympathetic trunk C8 T1 Superior cervical ganglion C8 Head and neck Sympathetic trunk Vagus n. T1 Sympathetic (prevertebral) ganglia T5 Celiac ganglionSympathetic trunk T1 Thoracic splanchnic nn. Dorsal Vagus n. vagal nucleus Sympathetic (prevertebral) ganglia Celiac ganglion Dorsal vagal nucleus Vagus n. Sympathetic Thoracic (prevertebral) splanchnic nn. ganglia T5 L1 Lumbar splanchnic nn. Dorsal vagal nucleus Parasympathetic Sympathetic C8 T5 Head and neck Parasympathetic Celiac ganglion L1 Lumbar splanchnic nn. Thoracic splanchnic nn. Sacral splanchnic nn. S2 Sacral splanchnic nn. L1 Lumbar **Inferior Superior and inferior splanchnic nn. hypogastric mesenteric ganglia {with intermesenteric plexus) plexus S2 S4 **Inferior Superior and inferior Pelvic splanchnic nn. hypogastric mesenteric ganglia {with intermesenteric plexus) Sympathetic plexus preganglionic fibers S4 Pelvic splanchnic nn. Sympathetic preganglionic fibers S2 Sympathetic postganglionic fibers Sympathetic postganglionic fibers Sacral **Minimal sympathetic preganglionic fibers traveling sympathetic preganglionic fibers traveling Parasympathetic preganglionic fibers splanchnic nn. the sacral splanchnic nerves will synapse**Minimal through in Parasympathetic preganglionic fibers through the sacral splanchnic nerves will synapsepostganglionic in S4 the ganglia located in the inferior hypogastric plexus Parasympathetic fibers the ganglia located in the inferior hypogastric plexus Parasympathetic postganglionic fibers **Inferior Superior and inferior hypogastric mesenteric ganglia Pelvic splanchnic nn. {with intermesenteric plexus) plexus Sympathetic preganglionic fibers Sympathetic postganglionic fibers **Minimal sympathetic preganglionic fibers traveling Parasympathetic preganglionic fibers through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus Parasympathetic postganglionic fibers Table 16.4 Effects of the autonomic nervous system in the abdomen and pelvis Organ (organ system) Gastrointestinal tract Parasympathetic effect Longitudinal and circular muscle fibers ↓ motility ↑ motility Sphincter muscles Contraction Relaxation Glands ↓ secretions ↑ secretions Splenic capsule Contraction Liver ↑ glycogenolysis/gluconeogenesis Pancreas Urinary bladder 212 Sympathetic effect No effect Endocrine pancreas ↓ insulin secretion Exocrine pancreas ↓ secretion ↑ secretion Detrusor vesicae Relaxation Contraction Functional bladder sphincter Contraction Inhibits contraction Seminal glands and ductus deferens Contraction (ejaculation) Uterus Contraction or relaxation, depending on hormonal status Arteries Vasoconstriction Vasodilation of the arteries of the penis and clitoris (erection) Suprarenal glands (medulla) Release of adrenalin No effect Urinary tract Vasoconstriction (↓ urine formation) Vasodilation Kidney No effect Ganglia Subplexus Distribution Celiac plexus Sympathetic trunk with lumbar ganglia Celiac ganglia Hepatic plexus • Liver, gallbladder Gastric plexus • Stomach Splenic plexus • Spleen Pancreatic plexus • Pancreas 16 Neurovasculature Autonomic plexuses in the abdomen and pelvis Table 16.5 Superior mesenteric plexus Superior mesenteric ganglion — • Pancreas (head) • Duodenum • Jejunum • Ileum • Cecum • Colon (to left colic flexure) • Ovary Suprarenal and renal plexus Aorticorenal ganglion Intermesenteric plexus Ureteral plexus • Suprarenal gland • Kidney • Proximal ureter Ovarian/testicular plexus — Lumbar splanchnics — • Ovary/testis Inferior mesenteric plexus Iliac plexus Inferior mesenteric ganglion Left colic plexus • Left colic flexure Superior rectal plexus • Descending and sigmoid colon • Upper rectum Superior hypogastric plexus — Hypogastric nn. • Pelvic viscera Inferior hypogastric plexus Sacral splanchnic Middle and inferior rectal plexus • Middle and lower rectum Prostatic plexus • Prostate • Seminal gland •B ulbourethral gland Deferential plexus • Ductus deferens • Epididymis Uterovaginal plexus • Uterus • Uterine tube Vesical plexus • Urinary bladder Ureteral plexus • Ureter (ascending from pelvis) Sacral ganglia Hypogastric nn. Pelvic ganglia Ganglion impar • Ejaculatory duct • Penis • Urethra • Vagina • Ovary Note: The two sacral sympathetic trunks converge and terminate in front of the coccyx in a small ganglion, the ganglion impar. 213 Abdomen Autonomic Innervation & Referred Pain Pain afferents from the viscera (visceral pain) and dermatomes (somatic pain) terminate at the same processing neurons in the posterior horn of the spinal cord. The convergence of these visceral and somatic affer­ ent fibers confuses the relationship between the pain’s origin and its Fig. 16.40 Autonomic innervation of the liver, gallbladder, and stomach perception. This phenomenon is called referred pain. The pain impulses from a particular internal organ are consistently projected to the same well-defined skin area. Thus,Posterior the area of skin that the pain is projected vagal trunk to provides crucial information regarding what organ is affected. Sympathetic trunk Posterior vagal trunk Anterior vagal trunk Right greater splanchnic n. Anterior vagal trunk Right greater splanchnic n. Gallbladder Left greater splanchnic n Hepatic br. of posterior vagal trunk Liver and gallbladder Celiac ganglia Stomach Celiac br. of anterior vagal trunk Left greater splanchnic n. Hepatic br. of posterior vagal trunk Sympathetic trunk Celiac ganglia Celiac br. of anterior vagal trunk BZones of referred pain from the liver, gallbladder, and stomach. Posterior gastric plexu Pyloric br. of anterior vagal trunk Posterior gastric plexus ASchematic of celiac plexus distribution to the liver, gallbladder, and stomach. Pyloric br. of anterior vagal trunk Hepatic plexus Hepatic br. of anterior vagal trunk Hepatic plexus Pyloric br. of posterior vagal trunk Hepatic br. of anterior vagal trunk Sympathetic preganglionic fibers Sympathetic postganglionic fibers Pyloric br. of posterior vagal trunk Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Symp trunk Posterior vagal trunk Sympathetic preganglionic fibers Sympathetic postganglionic fibers Fig. 16.41 Autonomic innervation of the pancreas, duodenum, and spleen Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Posterior vagal trunk Sympathetic trunk Anterior vagal trunk Celiac ganglia Anter vagal Left greater splanchnic n. Celiac ganglia Splenic plexus Brs. of celiac plexus to duodenum Splenic plexus Brs. of celiac plexus to duodenum BZones of referred pain from the pan­ creas. There are no zones associated with the duodenum and spleen. Brs. of superior mesenteric plexus to pancreas and duodenum Superior mesenteric ganglion Brs. of superior mesenteric plexus to pancreas and duodenum Sympathetic preganglionic fibers 214 Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Pancr plexu Superior mesente ganglion Pancreatic plexus ASchematic of celiac plexus distribution to the pancreas, ­duodenum, and spleen. Left g splan Sympathetic preganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Fig. 16.42 Autonomic innervation of the midgut and hindgut Sympathetic Sympathetic trunk trunk Posterior Posterior vagal trunk vagal trunk Celiac Celiac ganglia ganglia Superior Superior mesenteric mesenteric Small ganglion ganglion intestine Greater splanchnic n. Greater splanchnic n. (T5-T9) (T5-T9) Posterior vagal trunk Celiac ganglia Lesser splanchnic n. (T10-T11) Superior mesenteric ganglion Superior mesenteric plexus Least splanchnic n. (T12) Sacral splanchnic nn. Sacral splanchnic nn. (S1-S3) (S1-S3) Intermesenteric plexus Lumbar splanchnic n. (L1-L2) Inferior mesenteric ganglion Lumbar splanchnic n. (L3-L5) Inferior mesenteric plexus Superior rectal plexus Inferior rectal plexus Inferior hypogas Inferior hypogas plexus and plexus and pelvic ganglia* pelvic ganglia* Sympathetic preganglionic fibers Sympathetic preganglionic fibers Sympathetic postganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Parasympathetic postganglionic fibers Sacral splanchnic nn. (S1-S3) Inferior hypogastric plexus and pelvic ganglia** Inferior Inferior p p intestine. Pelvic splanchnic nn. Pelvic splanchnic nn. (S2-S4) (S2-S4) Superior hypogastric plexus Pelvic splanchnic nn. (S2-S4) Interm Interm p p Large intestine Lumbar splanchnic n. Inferior Lumbar splanchnic n. Inferior (L1-L2) mesenteric ganglion (L1-L2) mesenteric ganglion Lumbar splanchnic n. Lumbar splanchnic n. (L3-L5) BZones of referred pain Superior Superior (L3-L5) hypogastric plexus plexus from the small andhypogastric large Sympathetic trunk Greater splanchnic n. (T5-T9) 16 Neurovasculature Lesser splanchnic n. Lesser splanchnic n. (T10-T11) (T10-T11) Least splanchnic n. Least splanchnic n. (T12) (T12) Su Su me me p p Middle rectal plexus **Minimal sympathetic preganglionic fibers traveling **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus. the ganglia located in the inferior hypogastric plexus. ASchematic of superior mesenteric, Sympathetic preganglionic fibers inferior mesenteric, and inferior Sympathetic postganglionic fibers hypogastric ­plexuses distribution. Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in Fig.the16.43 innervation ganglia Autonomic located in the inferior hypogastric plexus. Sympathetic trunk of the kidneys and upper ureters Posterior vagal trunk Sympathetic trunk Lesser splanchnic n. (T10-T11) Posterior vagal trunk Aorticoren ganglion Lesser splanchnic n. (T10-T11) Kidney Least splanchnic n. (T12) Aorticorenal ganglion First lumbar splanchnic n. Least splanchnic n. (T12) BZones of referred pain from Renal the left kidney and bladder. First lumbar splanchnic n. ganglia Renal plexus ASchematic of renal and ureteral plexuses distribution. Urinary bladder Renal ganglia Sympathetic preganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Ureteral plexus Renal plexus Ureteral plexus Sympathetic preganglionic fibers Upper ureter Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers 215 Abdomen Innervation of the Foregut & Urinary Organs Fig. 16.44 Innervation of the foregut and spleen Anterior view. Removed: Lesser omentum, ascending colon, and parts of the transverse colon. Opened: Omental bursa. The anterior and poste­ rior vagal trunks each produce a celiac, hepatic, and pyloric branch, and a gastric plexus. See p. 214 for schematic. Posterior vagal trunk, celiac br. Anterior vagal trunk Anterior gastric plexus Anterior vagal trunk, hepatic br. Gastric plexus (on left gastric a.) Posterior vagal trunk, hepatic br. Splenic plexus Anterior vagal trunk, pyloric br. Left greater splanchnic n. Left lesser splanchnic n. Margin of hepatoduodenal lig. Celiac ganglia Hepatic plexus (on common hepatic a.) Brs. of gastric plexus (on gastro­ omental aa.) Pancreatic plexus (on pancreatico­ duodenal aa.) Superior mesenteric plexus (on superior mesenteric a.) Clinical box 16.9 Organization of the enteric plexus The enteric plexus is the portion of the autonomic nervous system that specifically serves all the organs of the gastrointestinal tract. Located within the wall of the digestive tube (intramural nervous system), it is subject to both sympathetic and parasympathetic influences. Congenital absence of the enteric plexus leads to severe disturbances of gastrointestinal transit (e.g., Hirschsprung disease). The enteric plexus has basically the same organization throughout the gastrointestinal tract, although there is an area in the wall of the lower rectum that is devoid of ganglion cells. Three subsystems are distinguished in the enteric plexus: • Submucosal plexus (Meissner’s plexus) • Myenteric plexus (Auerbach’s plexus) • Subserosal plexus 216 Muscularis externa, longitudinal layer Muscularis externa, circular layer Submucosa Serosa Mucosa Subserosal plexus Myenteric plexus Submucosal plexus 16 Neurovasculature Fig. 16.45 Innervation of the urinary organs Anterior view of the male abdomen and pelvis. Removed: Peritoneum, majority of stomach, and abdominal organs except kidneys, suprarenal glands, and bladder. See pp. 215 and 282 for schematic. Right greater splanchnic n. Posterior vagal trunk Right lesser splanchnic n. Anterior vagal trunk Celiac ganglion Suprarenal plexus Renal plexus Aorticorenal ganglia Superior mesen­ teric ganglion Intermesenteric plexus Sympathetic trunk, lumbar ganglia Ureteral plexus Inferior mesen­ teric ganglion Testicular plexus Inferior mesen­ teric plexus Iliac plexus Sympathetic trunk, sacral ganglia Right hypo­ gastric nn. Pelvic splanchnic nn. Vesical plexus Superior hypo­ gastric plexus Left hypo­ gastric n. 1st sacral n., anterior ramus Inferior hypo­ gastric plexus Middle rectal plexus Prostatic plexus 217 Abdomen Innervation of the Intestines Fig. 16.46 Innervation of the small intestine Anterior view. Partially removed: Stomach, pancreas, and transverse colon (distal part). See p. 215 for schematic. Anterior vagal trunk, hepatic br. Right greater splanchnic n. Posterior vagal trunk Anterior vagal trunk Posterior vagal trunk, celiac br. Left greater splanchnic n. Hepatic plexus Anterior vagal trunk, pyloric br. Aorticorenal ganglion Superior mesen­ teric ganglion Testicular (ovarian) plexus Right colic a. (with autonomic plexus) Ileocolic a. (with autonomic plexus) 218 Celiac ganglia Splenic plexus Left lesser splanchnic n. Renal plexus Superior mesenteric plexus Jejunal and ileal aa. (with autonomic plexuses) 16 Neurovasculature Fig. 16.47 Innervation of the large intestine Anterior view. Removed: Small intestine. Reflected: Transverse and sigmoid colons. See p. 215 for schematic. Transverse colon Middle and right colic aa. (with autonomic plexuses) Intermesenteric plexus Ileocolic a. (with autonomic plexus) Left colic a. (with autonomic plexus) Descending colon Inferior mesen­ teric ganglion Inferior mesen­ teric plexus Ascending colon Superior hypo­ gastric plexus Right hypo­ gastric nn. Superior rectal a. (with autonomic plexus) Sigmoid aa. (with autonomic plexus) Inferior hypo­ gastric plexus, brs. to descending colon and sigmoid colon 219 17 Sectional & Radiographic Anatomy Abdomen Sectional Anatomy of the Abdomen Fig. 17.1 Transverse sections of the abdomen Inferior view. Parietal peritoneum Falciform lig. of liver Common hepatic a. Visceral peritoneum Liver, left lobe Liver, right lobe Diaphragm, costal part Gallbladder Splenic a. Portal v. Stomach Lumbar l.n. (preaortic) Inferior vena cava Abdominal aorta Left suprarenal gland Right suprarenal gland Left kidney Left colic flexure Diaphragm, costal part T12 vertebra Spleen Vertebral canal with spinal cord A Section through T12 vertebra. Internal thoracic Transverse a. and v. Duodenum colon Common bile duct Greater omentum Pyloric part Superior mesenteric a. and v. Anterior wall Gallbladder Liver, right lobe Posterior wall Inferior vena cava Intercostal v., a., and n. Omental bursa Intermediate lumbar l.n. Splenic v. Pancreas Right suprarenal gland Spleen Kidney (with right renal a.) Transverse colon Descending colon Abdominal L1 vertebra aorta 220 BSection through L1 vertebra. Stomach Spinal cord (in vertebral canal) Vertebral venous plexus Lateral lumbar l.n. Perirenal fat capsule Left kidney Left colic flexure Pancreas, Superior mesenteric a. and v. head Stomach, body Jejunal a. Celiac l.n. Duodenum, descending part Transverse mesocolon Gallbladder Jejunum 17 Sectional & Radiographic Anatomy Transverse colon Descending colon Duodenojejunal flexure Liver Right kidney C Section through L2 vertebra. Psoas major Inferior vena cava Spinal cord Abdominal aorta Ureter 221 Abdomen Radiographic Anatomy of the Abdomen (I) Fig. 17.2 CT of the abdomen: Transverse sections (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Jejunum Gallbladder Stomach (pylorus) Portal vein (right br.) Liver (right lobe) A B C Portal v. Inferior vena cava Right suprarenal gland A Transverse section through T12 vertebral level Abdominal aorta in aortic hiatus Descending colon Pancreas (body) Splenic a. Common hepatic a. Spleen Splenic a. and v. Diaphragm (lumbar part, left crus) Transverse colon Duodenum Pancreas (head) Portal v. (confluence) Jejunum Splenic v. Pancreas (tail) Right hepatic v. Inferior vena cava Celiac trunk Abdominal aorta Right suprarenal gland and (superior) suprarenal a. Left lung (costodiaphragmatic recess) B Transverse section through L1 vertebral level Liver (right lobe) Duodenum (descending part) Right renal a. and v. Abdominal aorta Right kidney (renal pyramid, medulla) Psoas major muscle C Transverse section through L2 vertebral level 222 Left kidney (superior pole) Superior mesenteric a. and v. Pancreas (head) Descending colon Duodenum (ascending part) Inferior mesenteric v. Left renal v. Left kidney (hilum) Inferior vena cava Ileocolic a. and v. D E F Liver (right lobe) Duodenum (horizontal part) Right kidney (pelvis) Inferior vena cava Root of mesentery Superior mesenteric a. and v. Jejunum Posterior paracolic space Abdominal aorta Psoas major muscle Quadratus lumborum muscle DTransverse section through L3 vertebral level Posterior pararenal space Spinal canal with cauda equina 17 Sectional & Radiographic Anatomy Small intestine Umbilicus Right testicular a. and v. Rectus abdominis muscle External oblique muscle Internal oblique muscle Transverse abdominis muscle Right kidney (renal pyramid, medulla) Abdominal aorta Inferior vena cava Right ureter E Transverse section through L4 vertebral level Small intestine Ascending colon Anterior superior iliac crest Iliacus muscle Wing of ilium (superior border) Gluteus medius muscle F Transverse section through L5 vertebral level Lumbar plexus Descending colon Common iliac arteries Psoas major muscle Inferior vena cava (confluence) 223 Abdomen Radiographic Anatomy of the Abdomen (II) Fig. 17.3 CT of the abdomen: Sagittal section through the aorta (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Heart Liver (left lobe) Stomach Pancreas Celiac trunk Transverse colon Superior mesenteric a. Jejunum Right renal v. Lumbar vertebral body (L2) Abdominal aorta Duodenum (horizontal part) Promontory of sacrum Rectum Urinary bladder Fig. 17.4 CT of the Abdomen: Coronal section through the kidneys (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Stomach (fundus) Liver (right lobe) Inferior vena cava Right kidney, superior pole, and right renal a. Renal pelvis Psoas muscle Spleen with splenic a. and v. Pancreas (tail) Left renal v. and a. Left kidney (renal cortex) Inferior mesenteric v. Iliacus muscle Gluteus medius muscle Fig. 17.5 Radiograph of intravenous pylegram 12th rib Anterior view. Common iliac a. and v. (left) Major calyces Renal pelvis Right ureter Inferior pole of left kidney Distal ureter Urinary bladder 224 Fig. 17.6 Radiographs of double contrast barium enema. Anterior view. Jejunum Left colic flexure Right colic flexure Transverse colon Colonic haustra Ascending colon Descending colon 17 Sectional & Radiographic Anatomy Circular folds Sacrum Cecum Ilium Sigmoid colon Ileum A Small intestine. (Reproduced courtesy of Universitätsmedizin Mainz, Klinik und Poliklinik für Diagnostische und Interventionelle Radiologie.) B Large intestine. (Reproduced courtesy of Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig Holstein, Campus Kiel: Prof. Dr. Med. S. Müller-Huelsbeck.) Fig. 17.7 MRI of the intestines Coronal view. Sectional imaging modalities like CT and MR have mostly replaced conventional radiographs in the evaluation of gastrointestinal disease. (Reproduced from Krombach GA, Mahnken AH. Body Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) TC TC TC * AC DC BB A Jejunum (arrow) B Ileum (arrow), transverse colon (TC), urinary bladder (B) C Ascending colon (AC), descending colon (DC), transverse colon (TC), * small bowel and mesenteric structures. 225 Pelvis & Perineum 22 Neurovasculature 18 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 19 Bones, Ligaments & Muscles Pelvic Girdle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female & Male Pelvis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female & Male Pelvic Measurements . . . . . . . . . . . . . . . . . . . Pelvic Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Pelvic Floor & Perineum . . . . . . . . . . . . . . . . . Pelvic Floor & Perineal Muscle Facts. . . . . . . . . . . . . . . . . . . . 230 232 234 236 238 240 20 Spaces 268 270 272 274 276 278 280 282 284 23 Sectional & Radiographic Anatomy Contents of the Pelvis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Peritoneal Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244 Pelvis & Perineum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 21 Internal Organs Rectum & Anal Canal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ureters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Urinary Bladder & Urethra . . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the Genital Organs . . . . . . . . . . . . . . . . . . . . . . . Uterus & Ovaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments & Fascia of the Deep Pelvis . . . . . . . . . . . . . . . . . . Vagina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Female External Genitalia . . . . . . . . . . . . . . . . . . . . . . . . . . . . Penis, Testis & Epididymis . . . . . . . . . . . . . . . . . . . . . . . . . . . . Male Accessory Sex Glands. . . . . . . . . . . . . . . . . . . . . . . . . . . Overview of the Blood Supply to Pelvic Organs & Wall . . . . . Arteries & Veins of the Male Pelvis . . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Female Pelvis . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Rectum & External Genitalia . . . . . . . Lymphatics of the Pelvis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lymph Nodes of the Genitalia. . . . . . . . . . . . . . . . . . . . . . . . . Autonomic Innervation of the Genital Organs. . . . . . . . . . . . Autonomic Innervation of the Urinary Organs & Rectum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Male & Female Perineum . . . . . . . . 248 250 252 254 256 258 260 262 264 266 Sectional Anatomy of the Pelvis & Perineum. . . . . . . . . . . . . 286 Radiographic Anatomy of the Female Pelvis. . . . . . . . . . . . . 288 Radiographic Anatomy of the Male Pelvis . . . . . . . . . . . . . . . 290 18 Surface Anatomy Pelvis & Perineum Surface Anatomy Fig. 18.1 Palpable structures of the pelvis Anterior view. The structures are common to both male and female. See pp. 2–3 for structures of the back. Transumbilical plane (L3–4 disk) Anterior superior iliac spine (ASIS) Inguinal lig. Pubic symphysis Pubic tubercle A Bony prominences, female pelvis. Anterior superior iliac spine (ASIS) Superficial inguinal ring Sartorius Quadriceps femoris B Musculature, male pelvis. 228 The perineum is the inferiormost portion of the trunk, between the thighs and buttocks, extending from the pubis to the coccyx and superiorly to the inferior fascia of the pelvic diaphragm, including all of the structures of the anal and urogenital triangles (Fig. 18.2A). The bilateral boundaries of the perineum are the pubic symphysis, ischio­ pubic ramus, ischial tuberosity, sacrotuberous ligament, and coccyx. 18 Surface Anatomy Fig. 18.2 Regions of the female perineum Lithotomy position. Prepuce of clitoris Mons pubis Glans of clitoris Labium minus External urethral orifice Vagina (vaginal orifice) Ischiopubic ramus Posterior labial commissure Labium majus Urogenital triangle Ischial tuberosity Anal triangle Perineal region Perineal raphe Coccyx Ischial spine Anus Posterior commissure of vagina Sacrum A Perineal region. B Surgical gynecological perineum. Lateral crease of thigh Surgical gynecological perineum Anterior border of anus Fig. 18.3 Regions of the male perineum Lithotomy position. Pubic symphysis Scrotum Penis Glans of penis Perineal raphe Ischiopubic ramus Urogenital triangle Ischial tuberosity Anal triangle Perineal region Anus Coccyx Ischial spine A Perineal region. Surgical perineum Sacrum B Surgical perineum. Posterior border of root of scrotum Lateral crease of thigh Anterior border of anus 229 19 Bones, Ligaments & Muscles Pelvis & Perineum Pelvic Girdle The pelvis is the region of the body inferior to the abdomen and surrounded by the pelvic girdle, which is the two coxal (hip) bones and the sacrum that connect the vertebral column to the femur. The two coxal bones are connected to each other at the cartilaginous pubic symphysis and to the sacrum via the sacroiliac joints, creating the pelvic brim (red, Fig. 19.1). The stability of the pelvic girdle is necessary for the transfer of trunk loads to the lower limb, which occurs in normal gait. Fig. 19.1 Pelvic girdle Fig. 19.2 Coxal bone Anterosuperior view. The pelvic girdle consists of the two coxal bones and the sacrum. Sacroiliac joint Right side (male). Coxal bone Iliac crest Pubic symphysis Iliac fossa Iliac tuberosity Anterior superior iliac spine Auricular surface of ilium Arcuate line Sacrum Anterior inferior iliac spine Ischial spine Acetabular rim Pectineal line Acetabulum Iliac crest Iliac tuberosity Iliac fossa Posterior superior iliac spine Anterior superior iliac spine Auricular surface of ilium Posterior inferior iliac spine Anterior inferior iliac spine Arcuate line Ilium, body Superior pubic ramus Ischial spine Pectineal line Ischial tuberosity A Anterior view. Pubis, body Pubic tubercle Ischium, body Symphyseal surface Inferior pubic ramus 230 Obturator foramen Obturator foramen Ischial ramus Ischial tuberosity B Medial view. Symphyseal surface Fig. 19.3 Triradiate cartilage of the coxal bone Right coxal bone, lateral view. The coxal bone consists of the ilium, ischium, and pubis. Iliac crest Ilium Ilium, body Acetabulum Pubis, body Superior pubic ramus Ischial spine Ischium Triradiate cartilage Acetabulum Pubis Inferior pubic ramus Ischium, body 19 Bones, Ligaments & Muscles Iliac wing Ischial ramus Ischial tuberosity Obturator foramen A Junction of the triradiate cartilage. B Radiograph of a child’s acetabulum. Fig. 19.4 Coxal bone Right side (male), lateral view. Anterior gluteal line Iliac crest Posterior gluteal line Gluteal surface Anterior superior iliac spine Posterior superior iliac spine Inferior gluteal line Anterior inferior iliac spine Posterior inferior iliac spine Acetabular rim Greater sciatic notch Lunate surface Acetabular fossa Acetabulum Acetabular notch Ischial spine Lesser sciatic notch Pubic tubercle Obturator foramen Ischial tuberosity 231 Pelvis & Perineum Female & Male Pelvis Fig. 19.5 Female pelvis Pubic tubercle Sacroiliac joint Iliac crest Iliac fossa Sacrum Anterior superior iliac spine Anterior inferior iliac spine Superior and inferior pubic rami Acetabular margin Ischial spine Pubic symphysis Obturator foramen Coccyx Pubic arch A Anterior view. Ischial ramus Iliac crest Sacral canal Iliac wing Posterior superior iliac spine Median sacral crest Greater sciatic notch Posterior inferior iliac spine Superior pubic ramus Lesser sciatic notch Ischial tuberosity Ischial spine Inferior pubic ramus Sacroiliac joint Iliac tuberosity Sacral hiatus B Posterior view. Sacral canal Promontory Ala of sacrum Iliac crest Inner lip Iliac tubercle Intermediate line Outer lip Arcuate line Iliac fossa Coccyx Anterior superior and inferior iliac spines Ischial spine Pubic crest C Superior view. 232 Pubic tubercle Pectineal line (pecten pubis) Clinical box 19.1 Childbirth A non-optimal relation between the maternal pelvis and the fetal head may lead to complications during childbirth, potentially necessitating a caesarean section. Maternal causes include earlier pelvic trauma and innate malformations. Fetal causes include hydrocephalus (disturbed circulation of cerebrospinal fluid, leading to brain dilation and cranial expansion). Fig. 19.6 Male pelvis Sacrum Superior articular process Pelvic surface 19 Bones, Ligaments & Muscles Iliac crest Ala Promontory Anterior superior and inferior iliac spines Posterior inferior iliac spine Anterior sacral foramina Pectineal line (pecten pubis) Pubic tubercle Acetabulum Ischial spine Pubic symphysis Obturator foramen Pubic arch A Anterior view. Iliac crest Illiac tuberosity Superior articular process Gluteal surface Sacral canal Iliac tubercle Posterior superior and inferior iliac spines Median sacral crest Sacral hiatus Posterior sacral foramina Acetabular margin Ischial spine Pubis B Posterior view. Inner lip Iliac crest Intermediate line Median sacral crest Coccyx Ischial tuberosity Superior articular process Ala of sacrum Outer lip Iliac fossa Base of sacrum Arcuate line Ischial spine C Superior view. Anterior superior and inferior iliac spines Pectineal line Pubic (pecten pubis) symphysis Iliopubic eminence 233 Pelvis & Perineum Female & Male Pelvic Measurements The pelvic inlet, the superior aperture of the pelvis, is the boundary between the abdominal and pelvic cavities. It is defined by the plane that passes through its edge, the pelvic brim, which is the prominence of the sacrum, the arcuate and pectineal lines, and the upper margin of the pubic symphysis. Occasionally, the terms pelvic inlet and pelvic brim are used interchangeably. The pelvic outlet is the plane of the inferior aperture, passing through the pubic arch, the ischial tuberosities, the inferior margin of the sacrotuberous ligament, and the tip of the coccyx. Female Male Table 19.1 Gender-specific features of the pelvis Structure ♀ ♂ False pelvis Wide and shallow Narrow and deep Pelvic inlet Transversely oval Heart-shaped Pelvic outlet Roomy and round Narrow and oblong Ischial tuberosities Everted Inverted Pelvic cavity Roomy and shallow Narrow and deep Sacrum Short, wide, and flat Long, narrow, and convex Subpubic angle 90–100 degrees 70 degrees Pubic symphysis Subpubic angle A Male vs. female pelvis. B Female. C Male. Fig. 19.7 True and false pelvis The pelvis is the region of the body inferior to the abdomen, surrounded by the pelvic girdle. The false pelvis is immediately inferior to the abdominal cavity, between the iliac alae, and superior to the pelvic inlet. The true pelvis is the bony-walled space between the pelvic inlet and the pelvic outlet. It is bounded inferiorly by the pelvic diaphragm, also called the pelvic floor. Plane of pelvic inlet Plane of pelvic inlet Symphyseal surface Plane of pelvic outlet A Female. Midsagittal section, viewed from left side. 234 Coccyx Symphyseal surface Plane of pelvic outlet B Male. Midsagittal section, viewed from left side. Coccyx The true conjugate, the distance between the promontory and the most posterosuperior point of the pubic symphysis, is the narrowest AP (anteroposterior) diameter of the pelvic (birth) canal. This diameter is difficult to measure due to the viscera, so the diagonal conjugate, the distance between the promontory and the inferior border of the pubic symphysis, is used to estimate it. The linea terminalis is part of the border defining the pelvic inlet (pelvic brim). Diagonal conjugate True conjugate Linea terminalis Plane of pelvic inlet Plane of pelvic outlet ~60° 19 Bones, Ligaments & Muscles Fig. 19.8 Narrowest diameter of female pelvic canal ~15° Fig. 19.9 Pelvic inlet and outlet The measurements shown are applicable to both male and female. The transverse and oblique diameters of the female pelvic inlet are obstetrically important, as they are the measure of the diameter of the pelvic (birth) canal. The interspinous distance is the narrowest diameter of the pelvic outlet. Interspinous diameter Right oblique diameter Transtubercular distance Left oblique diameter Transverse diameter of pelvic inlet plane Interspinous distance Linea terminalis Pelvic inlet plane Pelvic inlet plane A Female pelvis, superior view. Pelvic inlet outlined in red. Pubic symphysis B Male pelvis, superior view. Pelvic inlet outlined in red. Superior pubic ramus Superior pubic ramus Inferior pubic ramus Pubic symphysis Ischial ramus Ischial tuberosity Coccyx Coccyx C Female pelvis, inferior view. Pelvic outlet outlined in red. DMale pelvis, inferior view. Pelvic outlet outlined in red. 235 Pelvis & Perineum Pelvic Ligaments Fig. 19.10 Ligaments of the pelvis Sacral promontory Male pelvis. Anterior longitudinal lig. Iliolumbar lig. Anterior sacroiliac ligs. Sacrotuberous lig. Anterior superior iliac spine Inguinal lig. Anterior inferior iliac spine Sacrospinous lig. Coccyx Ischial spine Pectineal lig. Pubic symphysis Pubic tubercle Obturator membrane A Anterosuperior view. L4 spinous process Iliac crest Iliolumbar lig. Iliac tubercle Ilium, gluteal surface Posterior superior iliac spine Short posterior sacroliac ligs. Posterior sacroiliac ligs. B Posterior view. On the right, the superficial part of the posterior sacroiliac ligament has been removed to reveal long and short posterior sacroiliac ligaments which blend with the deeper interosseous sacroiliac ligament. 236 Posterior inferior iliac spine Greater sciatic foramen Long posterior sacroiliac lig. Sacrospinous lig. Lesser sciatic foramen Sacrotuberous lig. Ischial spine Obturator membrane Coccyx Ischial tuberosity Fig. 19.11 Ligaments of the sacroiliac joint Fig. 19.12 Pelvic ligament attachment sites on the coxal bone Male pelvis, midsagittal section. Intervertebral disk L4/5 L5 spinous process Interosseous sacroiliac lig. Sacrum Promontory Anterior superior iliac spine Sacral canal Sacrospinous lig. Anterior sacroiliac lig. Greater sciatic foramen Arcuate line Sacrospinous lig. Pectineal line Sacral hiatus 19 Bones, Ligaments & Muscles Left coxal bone, medial view. Ligament attachments are shown in green. Sacrotuberous lig. Pubic symphysis Ischial spine Coccyx Sacrotuberous lig. Obturator canal Lesser sciatic foramen Symphyseal surface Obturator membrane Ischial tuberosity A Right half of pelvis, medial view. Posterior superior iliac spine Sacrum Sacral canal Iliac tuberosity Posterior sacroiliac lig. Interosseous sacroiliac lig. Anterior sacral foramina Sacral tuberosity Anterior sacroiliac lig. Sacroiliac joint Sacrospinous lig. Ischial spine Sacrotuberous lig. Ilium Greater sciatic foramen Coccyx Anterior sacrococcygeal lig. Lesser sciatic foramen Acetabulum Pubic symphysis B Oblique section, superior view. 237 Pelvis & Perineum Muscles of the Pelvic Floor & Perineum Fig. 19.13 Muscles of the pelvic floor Rectal hiatus Urogenital hiatus Prerectal fibers Puborectalis Obturator canal Levator ani Pubococcygeus Obturator fascia (obturator internus) Iliococcygeus Ischial spine Tendinous arch of levator ani Coccygeus Piriformis Anococcygeal raphe A Superior view. Pubic symphysis Inferior pubic lig. Sacrum Prerectal fibers Obturator internus Urogenital hiatus Puborectalis Pubococcygeus Iliococcygeus Acetabulum Ischial tuberosity Levator ani Piriformis Rectal hiatus Coccyx Coccygeus B Inferior view. Anterior sacroiliac lig. Arcuate line Piriformis Coccygeus Obturator internus fascia Posterior superior iliac spine Ischial spine Tendinous arch of levator ani Anococcygeal lig. Pubic symphysis Piriformis Coccygeus Sacrospinous lig. Pubic tubercle Sacrotuberous lig. Obturator foramen Coccyx Ischial spine DRight lateral view. 238 Levator ani Deep transverse perineal C Medial view of right hemipelvis. Iliococcygeus Pubococcygeus Puborectalis Levator ani Fig. 19.14 Muscles and fascia of the pelvic floor and perineum, in situ Bulbospongiosus Ischiocavernosus Superficial perineal (Colles’) fascia Perineal membrane Perineal body Superficial transverse perineal Ischial tuberosity Obturator internus Obturator fascia Gluteus maximus Inferior fascia of pelvic diaphragm Levator ani Anococcygeal lig. A Female. 19 Bones, Ligaments & Muscles Lithotomy position. Removed on left side: Superficial perineal (Colles’) fascia, inferior fascia of the pelvic diaphragm, and obturator fascia. Note: The green arrows are pointing forward to the anterior recess of the ischioanal fossa. Coccyx External anal sphincter Anal cleft Bulbospongiosus Ischiocavernosus Superficial perineal (Colles’) fascia Perineal membrane Ischial tuberosity Superficial transverse perineal Obturator fascia Obturator internus Gluteus maximus Inferior fascia of pelvic diaphragm Levator ani Anococcygeal lig. B Male. External anal sphincter Anococcygeal lig. Fig. 19.15 Genderrelated differences in structure of the levator ani Posterior view. Note the connective tissue gaps ­between muscular parts of the levator ani in the female. Levator ani A Male. B Female. External anal sphincter Connective tissue gaps 239 Pelvis & Perineum Pelvic Floor & Perineal Muscle Facts Fig. 19.16 Muscles of the pelvic floor Superior view. Iliococcygeus ② ① Obturator internus Anococcygeal lig. ③ ④ A Muscles of the pelvic diaphragm. Coccygeus Piriformis B Outermost layer of the pelvic floor. Muscles of the pelvic floor Table 19.2 Muscle Origin Insertion Innervation Action Superior pubic ramus (both sides of pubic symphysis) Anococcygeal lig. Nerve to levator ani (S4), inferior rectal n. Pelvic diaphragm: Supports pelvic viscera Ischial spine Direct branches from sacral plexus (S4–S5) Supports pelvic viscera, flexes coccyx Muscles of the pelvic diaphragm ① Puborectalis Levator ani Pubis (lateral to origin of ② Pubococcygeus puborectalis) ③ Iliococcygeus Anococcygeal lig., coccyx Internal obturator fascia of levator ani (tendinous arch) Lateral surface of coccyx and S5 segment ④ Coccygeus Muscles of the pelvic wall (parietal muscles) Piriformis* Sacrum (pelvic surface) Femur (apex of greater trochanter) Direct branches from sacral plexus (S1–S2) Hip joint: External rotation, stabilization, and abduction of flexed hip Obturator internus* Obturator membrane and bony boundaries (inner surface) Femur (greater trochanter, medial surface) Direct branches from sacral plexus (L5–S1) Hip joint: External rotation and abduction of flexed hip *The piriformis and obturator internus are considered muscles of the hip (see p. 426). The female and male external genitalia are shown on pp. 262–265. Fig. 19.17 Muscles of the perineum Inferior view. Bulbospongiosus Bulbospongiosus Ischiocavernosus Ischiocavernosus Perineal membrane Urethrovaginal sphincter Superficial transverse perineal Perineal membrane Deep transverse perineal Deep transverse perineal Superficial transverse perineal External anal sphincter A Superficial and deep perineal muscles in the male. 240 External urethral sphincter Compressor urethrae B Superficial and deep perineal muscles in the female. Table 19.3 Muscles of the perineum Origin Insertion ① Ischiocavernosus Ischial ramus Crus of clitoris or penis ② Bulbospongiosus Runs anteriorly from perineal body to clitoris (females) or penile raphe (males) ③ Superficial transverse Innervation Action Maintains erection by squeezing blood into corpus cavernosum of clitoris or penis Females: Compresses greater vestibular gland Males: Assists in erection Helps hold perineal body in median plane, holds the pelvic organs in place, and supports visceral canals through the muscles of the perineum Ischiopubic ramus Perineal body ④ Deep transverse perineal* Ishiopubic ramus Perineal body and external anal sphincter ⑤ External urethral sphincter Encircles urethra (division of deep transverse perineal muscle), in males ascends anteriorly to neck of the bladder; in females, some fibers surround the vagina as the urethrovaginal sphincter, others extend laterally as the compressor urethrae (See Figs. 21.9 and 21.11) Closes urethra ⑥ External anal sphincter Encircles anus (runs posteriorly from perineal body to anococcygeal lig.) Closes anus perineal Pudendal n. (S2–S4) 19 Bones, Ligaments & Muscles Muscle * Typically, this muscle is not developed in females and is replaced by smooth muscle tissue. When developed, it provides dynamic support to the pelvic organs. Fig. 19.19 Muscles of the female perineum Fig. 19.18 Muscles of the male perineum ② ① ① ③ ③ ⑥ A Muscles of the superficial pouch in the male. ② ⑥ A Muscles of the superficial pouch in the female. Compressor urethrae ⑤ ⑤ ④ ④ Urethrovaginal sphincter B Muscles of the deep pouch in the male. B Muscles of the deep pouch in the female. 241 20 Spaces Pelvis & Perineum Contents of the Pelvis Fig. 20.1 Male pelvis Parasagittal section, viewed from the right side. Right common iliac a. and v. Sigmoid mesocolon Tenia coli L5 vertebra Sigmoid colon Parietal peritoneum Right ductus deferens Rectus abdominis Rectovesical pouch Visceral peritoneum on bladder Visceral peritoneum on rectum Rectum Visceral pelvic fascia on bladder Visceral pelvic fascia on rectum Superior pubic ramus Right ureter Urinary bladder Inferior pubic ramus Levator ani Ischiocavernosus Right seminal gland Prostate External anal sphincter Bulbospongiosus Anus 242 Perineal body Rectoprostatic fascia 20 Spaces Fig. 20.2 Female pelvis Parasagittal section, viewed from the right side. Right common iliac a. and v. Sigmoid mesocolon Tenia coli L5 vertebra Sigmoid colon Uterine tube Lig. of ovary Round lig. of uterus Uterus Vesicouterine pouch Rectouterine pouch Visceral peritoneum on rectum Visceral peritoneum on bladder Rectum Visceral pelvic fascia on bladder Visceral pelvic fascia on rectum Superior pubic ramus Right ureter Urinary bladder Levator ani Inferior pubic ramus External anal sphincter Anus Perineal body Vagina Ischiocavernosus 243 Pelvis & Perineum Peritoneal Relationships Fig. 20.3 Peritoneal relationships in the pelvis: Female Broad lig. of uterus Rectum Rectouterine Rectouterine pouch fold Suspensory lig. of ovary Superior view. Uterine tube Left ovary Cecum Sigmoid colon Fundus of uterus Lig. of ovary Parietal peritoneum Paravesical fossa Round lig. of uterus Deep inguinal ring Vesicouterine pouch Transverse vesical fold A Lesser pelvis, anterosuperior view. Retracted: Small intestine loops and colon (portions). Fundus of uterus Rectum Lateral umbilical fold (with inferior epigastric a. and v.) Urinary bladder Rectus abdominis Median umbilical fold (with obliterated urachus) Supravesical fossa Medial umbilical fold (with obliterated umbilical a.) External iliac a. and v. Peritoneum, parietal layer Cardinal lig. Obturator internus Obturator fascia Levator ani Superior and inferior fascia of pelvic diaphragm Ischioanal fossa, anterior recess Perineal membrane Deep transverse perineal Vagina Superficial perineal fascia B Muscles (red) of the pelvic floor. Coronal section, anterior view. Vesicouterine pouch Urinary bladder Rectovaginal septum Retropubic space Peritoneal and subperitoneal spaces C (green) in the pelvis. Midsagittal section, viewed from the left side. 244 Perineal body Sigmoid colon Uterus Rectouterine pouch Retrorectal (presacral) space Rectum Ileum Rectum Rectovesical pouch 20 Spaces Fig. 20.4 Peritoneal relationships in the pelvis: Male Transverse vesical fold Superior view. Cecum Parietal peritoneum Ductus deferens Vermiform appendix Sigmoid colon Lateral inguinal fossa Lateral umbilical fold (with inferior epigastric a. and v.) Urinary bladder A Lesser pelvis, anterosuperior view. Retracted: Small intestine and colon (portions). Median umbilical fold (with obliterated urachus) Urinary bladder Rectus abdominis Medial umbilical fold (with obliterated umbilical a.) Peritoneum, parietal layer Paravesical space Obturator internus Superior and inferior fascia of pelvic diaphragm Levator ani Ischioanal fossa, anterior recess External urethral sphincter Perineal membrane Prostate Bulb of penis Crus of penis Inferior pubic ramus B Muscles (red) of the pelvic floor. Coronal section, anterior view. Peritoneal and subperitoneal spaces C (green) in the pelvis. Midsagittal section, viewed from the left side. Urinary bladder Rectovesical septum Retropubic space Perineal body Sigmoid colon Rectovesical pouch Retrorectal (presacral) space Rectum 245 Pelvis & Perineum Pelvis & Perineum The pelvis is the region of the body inferior to the abdomen, surrounded by the pelvic girdle. The false, or greater, pelvis is immediately inferior to the abdominal cavity, between the iliac alae, and superior to the pelvic inlet. The true, or lesser, pelvis is found between the pelvic inlet and the pelvic outlet and extends inferiorly to the pelvic diaphragm (levator ani and coccygeus ), a muscular sling attached to the boundaries of the Table 20.1 Divisions of the pelvis and perineum The levels of the pelvis are determined by bony landmarks (iliac alae and pelvic inlet/brim). The contents of the perineum are separated from the true pelvis by the pelvic diaphragm and two fascial layers. pelvic outlet. The perineum is the inferior most portion of the trunk, between the thighs and buttocks, extending from the pubis to the coccyx and superiorly to the pelvic diaphragm. The superficial perineal pouch lies between the membranous layer of the subcutaneous tissue (Colles’ ­fascia) and the perineal membrane. The deep perineal pouch lies between the perineal membrane and the inferior fascia of the pelvic diaphragm. Fig. 20.5 Pelvis and urogenital triangle Peritoneum Uterus Vagina Iliac crest • Ileum (coils) • Cecum and appendix False pelvis • Sigmoid colon • Common and external iliac aa. and vv. • Lumbar plexus (brs.) Pelvic inlet • Distal ureters Pelvis • Urinary bladder • Rectum ♀: Vagina, uterus, uterine tubes, and ovaries True pelvis ♂: Ductus deferens, seminal gland, and prostate • Internal iliac a. and v. and brs. Obturator internus Pelvic diaphragm (with fascia) Deep pouch Internal pudendal a. and v., pudendal n. Inferior pubic ramus Crus of clitoris and ischiocavernosus Perineal membrane Vestibular bulb and bulbospongiosus Vestibule of vagina Superficial Skin perineal (Colles’) fascia Superficial pouch A Female. Oblique section. • Sacral plexus • Inferior hypogastric plexus Pelvic diaphragm (levator ani & coccygeus) • Sphincter urethrae and deep transverse perineal mm. Urinary Peritoneum bladder Prostate • Urethra (membranous) • Vagina Deep pouch Superior fascia of pelvic diaphragm • Rectum • Bulbourethral gland • Ischioanal fossa • Internal pudendal a. and v., pudendal n. and brs. Perineum Perineal membrane • Ischiocavernosus, bulbospongiosus, and superficial transverse perineal mm. Superficial pouch • Urethra (penile) • Clitoris and penis • Internal pudendal a. and v., pudendal n. and branches Superficial perineal (Colles’) fascia Subcutaneous perineal space • Fat Obturator internus Levator ani Inferior fascia of pelvic diaphragm Perineal membrane Superficial perineal (Colles’) fascia Deep pouch Crus of penis and ischiocavernosus Urethra, spongy part B Male. Coronal section. Peritoneal cavity Visceral pelvic fascia Subperitoneal space Parietal pelvic fascia Skin Ischioanal fossa 246 BulboBulb of penis spongiosus Superficial pouch Fig. 20.6 Pelvis: Oblique section Suspensory lig. of ovary Anterior view. Right ureter Rectum Fundus of uterus External iliac a. and v. 20 Spaces Iliacus Ovary Round lig. of uterus Uterine tube Cardinal (transverse cervical) lig. Cervix of uterus Right ureter Paravaginal tissue (fascia) Obturator internus Vagina Ischioanal fossa, anterior recess Inferior pubic ramus Levator ani Deep transverse perineal A Female. Oblique section. Crus of clitoris (with ischiocavernosus) Superficial perineal (Colles’) fascia Urinary bladder Vestibule of vagina Internal urethral orifice Vestibular bulb (with bulbospongiosus) Ureteral orifice Paravesical fossa Gluteus minimus Femur, head Venous plexus Obturator internus Seminal colliculus Prostate Levator ani Urethra, membranous part Obturator externus Deep transverse perineal Quadratus femoris Inferior pubic ramus Crus of penis (with ischiocavernosus) Adductor mm. B Male. Coronal section. Superficial perineal (Colles’) fascia Bulb of penis (with bulbospongiosus) Subcutaneous perineal space 247 21 Internal Organs Pelvis & Perineum Rectum & Anal Canal Fig. 21.1 Rectum: Location Fig. 21.2 Closure of the rectum Left lateral view. The puborectalis acts as a muscular sling that kinks the anorectal junction. It functions in the maintenance of fecal continence. Sigmoid colon RLQ Rectum LLQ Coccyx A Anterior view. Pubococcygeus Pubis Ilium Puborectalis Sacrum Pubis Sacral flexure Ischium Perineal flexure Rectum Perineal flexure Left anterolateral view. B Fig. 21.3 Rectum in situ Coronal section, anterior view of the female pelvis. The upper third of the rectum is covered with visceral peritoneum on its anterior and lateral sides. The middle third is covered only anteriorly and the lower third is inferior to the parietal peritoneum. External iliac a. and v. Rectum Tenia coli Sigmoid mesocolon Sigmoid colon Ureter Parietal peritoneum Rectouterine (uterosacral) fold Superior and inferior fascia of pelvic diaphragm Obturator internus Pudendal n. Levator ani (pelvic diaphragm) Internal pudendal a. and v. External anal sphincter Perineal n. Ischioanal fossa Internal anal sphincter 248 Anal canal Transverse rectal fold Fig. 21.4 Rectum and anal canal Coronal section, anterior view with the anterior wall removed. 21 Internal Organs Peritoneal covering of rectum Superior transverse rectal fold Middle transverse rectal fold Circular layer Longitudinal layer Muscularis externa Parietal peritoneum Rectal ampulla Superior fascia of pelvic diaphragm Inferior transverse rectal fold Levator ani Anorectal junction Inferior fascia of pelvic diaphragm Hemorrhoidal plexus Anal canal Internal anal sphincter Deep part Anal columns External anal sphincter Superficial part Anal sinuses Anal valves Subcutaneous part Anal pecten (white zone) Corrugator cutis ani Anocutaneous line Anus Table 21.1 Anocutaneous line ② ③ ④ ⑤ Regions of the rectum and anal canal Region Epithelium ① Rectum Colon-like with crypts; simple columnar with goblet cells ① Anorectal junction Pectinate line Subcutaneous venous plexus Perianal skin ② Columnar zone Anal canal Anal canal ③ Anal pecten ④ Cutaneous zone ⑤ Perianal skin (pigmented) Stratified squamous, nonkeratinized Stratified squamous, keratinized with sebaceous glands Stratified squamous, keratinized with sebaceous glands, hairs, and sweat glands 249 Pelvis & Perineum Ureters Fig. 21.5 Ureters in situ Anterior view, male abdomen. Removed: Nonurinary organs and rectal stump. The ureters descend along the posterior abdominal wall in the retroperitoneal space. On each side, they enter the pelvis after crossing the common iliac artery at its bifurcation into the external and internal arteries. Celiac trunk Abdominal aorta Left middle suprarenal a. Left inferior phrenic a. and v. Left superior suprarenal a. Left suprarenal gland and v. Inferior vena cava Right suprarenal gland and v. Left inferior suprarenal a. Left renal a. and v. Right kidney Superior mesenteric a. Left testicular a. and v. Perirenal fat capsule Left kidney Ureteropelvic junction Ureter, abdominal part Inferior mesenteric a. Right testicular a. and v. Psoas major Right common iliac a. Iliacus Median sacral a. and v. Left internal iliac a. and v. Right internal iliac a. and v. Left superior gluteal a. Sacral plexus Anterior trunk of internal iliac a. and v. Left external iliac a. and v. Inferior epigastric a. and v. Right ductus deferens Rectum Ureterovesical junction Urinary bladder 250 Pubic symphysis Median umbilical lig. Ureter, pelvic part Fig. 21.6 Ureter in the male pelvis Pubic symphysis Superior view with peritoneum removed. Pubis Tendinous arch of levator ani Pelvic diaphragm, superior fascia Pubovesical muscles Bladder, body Bladder, apex Median umbilical lig. Right ductus deferens Left ductus deferens Tendinous arch of pelvic fascia Left ureter Rectum with peritoneal covering on anterior wall Fig. 21.7 Ureter in the female pelvis Superior view. The pelvic ureters pass under the uterine artery ­approximately 2 cm lateral to the cervix. Transverse vesical fold Pubis 21 Internal Organs Inferior (arcuate) pubic lig. Right ureter Pubis symphysis Median umbilical lig. Medial umbilical fold (occluded part of umbilical a.) Vesicouterine pouch Parietal peritoneum Bladder, body Left external iliac a. and v. Uterus, fundus Round lig. of uterus Passage of left ureter through broad lig. of uterus Uterus, posterior surface Left broad lig. of uterus Passage of right ureter through broad lig. of uterus Left uterine tube Uterosacral fold (with uterosacral lig.) Left ovary Left ovarian a. and v. in ovarian suspensory lig. Right ureter Left ureter Rectum Sacral promontory Rectouterine pouch Clinical box 21.1 Anatomical constrictions of the ureter There are three normal anatomical constrictions where a pain-causing kidney stone from the renal pelvis is apt to become lodged: First constriction: narrowing of the ureter as it passes over inferior renal pole (abdominal part) •Narrowing at the origin of the ureter from the renal pelvis (ureteropelvic junction) •Site where the ureter crosses over the external or common iliac vessels •Passage of the ureter through the bladder wall (ureterovesical junction). Possible constriction where the testicular or ovarian vessels pass anterior to the ureter Occasionally a fourth constriction can be identified where the testicular or ovarian artery and vein pass anterior to the ureter. Second constriction: ureter crosses over external iliac vessels (pelvic part) Third constriction: ureter traverses the bladder wall (intramural part) 251 Pelvis & Perineum Urinary Bladder & Urethra Fig. 21.8 Female urinary bladder and urethra Left common iliac a. and v. Suspensory lig. of ovary (with ovarian a. and v.) L5 vertebra Right uterine tube Right ureter Right external iliac a. and v. Right ovary and lig. of ovary Rectus abdominis Fundus of uterus Body of uterus Round lig. of uterus Rectum Cervix of uterus Urinary bladder Posterior vaginal fornix Anterior vaginal fornix Levator ani Pubic symphysis Vagina Clitoris Urethra External anal sphincter External urethral orifice Perineal membrane A Midsagittal section of pelvis, viewed from the left side. Right hemipelvis. Median umbilical lig. Interureteral fold Urogenital peritoneum Left ureter Apex of bladder Fundus of bladder Visceral pelvic fascia Right ureter, intramural part Ureteral orifice Neck of bladder Body of bladder Female urethra Bladder and urethra, left lateral view. B Urinary bladder, trigone Mucosa Detrusor m. Adventitia with visceral pelvic fascia Urinary bladder, neck Internal urethral orifice with bladder uvula Orifices of urethral glands Fig. 21.9 Urethral sphincter ­mechanism in the female External urethral sphincter Muscularis CTrigone and urethra, coronal section, ­anterior view. Vagina Compressor urethrae Urethra Urethrovaginal sphincter 252 Mucosa with longitudinal folds Submucosa Left ureter Anterolateral view. Urinary bladder Urinary bladder, body Urethra Fig. 21.10 Male urinary bladder and urethra Urinary bladder Rectovesical pouch Rectum Rectovesical septum Retropubic space Suspensory lig. of penis Ductus deferens, ampulla Penile fascia Ejaculatory duct 21 Internal Organs Pubic symphysis Prostate Penis, corpus cavernosum Bulbourethral gland External urethral sphincter Bulbospongiosus Penis, corpus spongiosum Urethra, spongy part Scrotal septum Prepuce A Midsagittal section of pelvis, viewed from left side. Right hemipelvis. Median umbilical lig. Urogenital peritoneum Ureteral orifice Interureteric crest Detrusor muscle Left ureter Apex of bladder Fundus of bladder Visceral pelvic fascia Body of bladder Ampulla of ductus deferens Prostate Male urethra B Bladder, urethra and prostate, left lateral view. Prostatic utricle Prostatic urethra Prostate Ejaculatory ducts Openings of ejaculatory ducts Prostate External urethral sphincter Seminal colliculus Neck of bladder, internal urethral orifice Internal urethral sphincter Dilator urethrae Internal urethral sphincter Fundus of bladder, trigone C Trigone, urethra and prostate, coronal ­section, anterior view. Prostatic urethra Bulb of penis Fig. 21.11 Urethral sphincter ­mechanism in the male Lateral view. 253 Pelvis & Perineum Overview of the Genital Organs The genital organs can be classified topographically (external versus internal) and functionally (Tables 21.2 and 21.3). Table 21.2 Internal genitalia Female genital organs Organ Function Ovary Germ cell and hormone production Uterine tube Site of conception and transport organ for zygote Uterus Organ of incubation and parturition Vagina (upper portion) Organ of copulation and parturition Vagina (vestibule) Labia majora and minora External genitalia Vulva Clitoris Right kidney Accessory copulatory organ Greater and lesser vestibular glands Production of mucoid secretions Mons pubis Protection of the pubic bone Right ureter Fig. 21.12 Female genital organs Suspensory lig. of ovary Ovary Right uterine tube Uterine tube Right ovary Uterus Round lig. of uterus Vagina Labia minora Vestibule A Internal and external genitalia. Glans and crus of clitoris Vestibular bulb Greater vestibular (Bartholin’s) gland Uterus Cervix of uterus Median umbilical lig. Vagina Urinary bladder Ureteral orifice Clitoris Urethra Greater vestibular (Bartholin's) gland Labium majus Labium minus B Urogenital system. Note: The female urinary and genital tracts are functionally separate, though topographically close. 254 Male genital organs Table 21.3 Function Testis Germ cell and hormone production Epididymis Storage reservoir for sperm Ductus deferens Accessory sex glands External genitalia 21 Internal Organs Internal genitalia Organ Transport organ for sperm Prostate Seminal glands Production of secretions (semen) Bulbourethral gland Penis Copulatory and urinary organ Urethra Conduit for urine and semen Scrotum Coverings of the testis Protection of testis Right kidney Fig. 21.13 Male genital organs Inguinal canal Ureter Urinary bladder Ductus deferens Ductus deferens, ampulla Seminal gland Right ureter Excretory duct Ejaculatory duct Bulbourethral gland Ductus deferens Penis Prostate Median umbilical lig. Deep transverse perineal Ductus deferens Urethra Epididymis Ureteral orifice Urinary bladder Seminal gland Testis Ejaculatory duct Penis, corpus cavernosum A Seminiferous structures. Prostate Penis, corpus spongiosum Bulbourethral gland Urethra, spongy part Bulb of penis, corpus spongiosum Glans of penis, corpus spongiosum Scrotum Testis Epididymis B Urogenital system. Note: The male urethra serves as a common urinary and genital passage. 255 Pelvis & Perineum Uterus & Ovaries Fig. 21.14 The broad ligament Peritoneal covering Regions of the broad ligament, sagittal ­section. The uterus and ovaries are suspended by the broad ligament of the uterus, which is composed of a double layer of peritoneum, arranged as a combination of mesenteries: the mesosalpinx, meso­varium, and mesometrium. Uterine tube Mesosalpinx Mesovarium Ovary Mesometrium Germinal epithelial covering Fig. 21.15 Ovary Right ovary, posterior view. Mesovarium Mesovarial margin Uterine tube Uterus, posterior surface Proper ovarian lig. Uterine pole Vascular pole Ovarian suspensory lig. Follicular stigma (bulge from Graafian follicle) Ovarian a. and v. Mesometrium Medial surface Free margin Fig. 21.16 Normal curvature and position of the uterus Midsagittal section, left lateral view. The position of the uterus can be described in terms of: ① Flexion, the angle between the longitudinal cervical axis and the longitudinal uterine axis; the normal position is anteflexion. ② Version, the angle between the l­ongitudinal cervical axis and longitudinal vaginal axis; the normal position is anteversion. Endometrium Longitudinal uterine axis (in uterine cavity) Longitudinal cervical axis (in cervical canal ) Myometrium Visceral peritoneum Fundus of uterus Rectouterine pouch A Body of uterus S Vesicouterine pouch Posterior vaginal fornix Uterine isthmus Supravaginal part Vaginal part 256 Uterine cervix Anterior vaginal fornix Longitudinal vaginal axis Longitudinal body axis Left uterine tube Ampulla Isthmus Fundus of uterus Lig. of ovary Mesosalpinx (with tubal brs. of uterine a. and v.) Infundibulum, uterine tube Left ovary 21 Internal Organs Fig. 21.17 Uterus and uterine tube Fimbriae at abdominal ostium Ovarian a. and v. (in suspensory lig. of ovary) Vesicular appendices Epoöphoron Body of uterus Embryonic remnants Mesometrium Right ureter Cervix of uterus Uterosacral lig. (in rectouterine fold) Vagina A Posterosuperior view. Left uterine tube Isthmus Ampulla Uterine part Uterine ostium Fundus of uterus Cavity of uterus Lig. of ovary Mesosalpinx Infundibulum Mesovarium Fimbriae at abdominal ostium Uterine pole Endometrium Vascular pole Right ovary Myometrium Cervix of uterus Internal os (at uterine isthmus) Supravaginal part Cervical canal Vaginal part Vaginal fornix, lateral part External os B Coronal section, posterior view with uterus straightened. Removed: Mesometrium. Vagina, anterior wall Clinical box 21.2 Ectopic pregnancy After fertilization in the ampulla of the uterine tube, the ovum usually implants in the wall of the uterine cavity. However, it may become implanted at other sites (e.g., the uterine tube or even the peritoneal cavity). Tubal pregnancies, the most common type of ectopic pregnancy, pose the risk of tubal wall rupture and potentially life-threatening bleeding into the peritoneal cavity. Tubal pregnancies are promoted by adhesion of the tubal mucosa, mostly due to inflammation. 257 Pelvis & Perineum Ligaments & Fascia of the Deep Pelvis Fig. 21.18 Ligaments of the female pelvis Superior view. Removed: Peritoneum, neurovasculature, and superior portion of the bladder to demonstrate only the fascial condensations (ligaments). Deep pelvic ligaments support the uterus within the pelvic cavity and prevent uterine prolapse, the downward displacement of the uterus into the vagina. Ilium Sacrum Uterosacral lig. Rectum Rectouterine lig. Cardinal (transverse cervical) lig. Uterus Round lig. of uterus Uterine tube Vesicouterine lig. Lig. of ovary Urinary bladder Pubovesical lig. Pubic symphysis Pubis Fig. 21.19 Ligaments of the deep pelvis in the female Superior view. Removed: peritoneum, neurovasculature, uterus and bladder. Uterosacral ligaments and the paracolpium support and help maintain the positions of the cervix and vagina in the pelvis. Piriformis Uterosacral lig. Rectum Cardinal (transverse cervical) lig. Fascia over obturator internus Cervix Tendinous arch of levator ani Paracolpium Tendinous arch of pelvic fascia Fascia over anterior vagina Levator ani Lateral lig. of the bladder Pubovesical lig. Obturator canal Urethra Pubic symphysis 258 Fig. 21.20 Fascia and ligaments of the female pelvis 21 Internal Organs are extensions of the tendinous arches that support the bladder and prostate. Endopelvic fascia, a loose areolar (fatty) tissue that fills the spaces between pelvic viscera, condenses to form “ligaments” (cardinal, lateral visceral, and lateral rectal ligaments; see Fig. 21.20) that provide passage for the ureters and neurovascular elements within the pelvis. Fascia of the pelvis plays an important role in the support of pelvic viscera. On either side of the pelvic floor, where the visceral fascia of the pelvic organs is continuous with the parietal fascia of the muscular walls, thickenings called tendinous arches of the pelvic fascia are formed. In females, the paracolpium—lateral connections between the visceral fascia and the tendinous arches—suspends and supports the vagina. Pubovesical ligaments (and puboprostatic ligaments in the male) Transverse section, through cervix, superior view. Pubovesical lig. Retropubic Vesicovaginal space Tendinous arch of pelvic fascia space Medial umbilical lig. Urinary bladder Inferior epigastric a. and v. Cervix Superior vesical a. in lateral vesicular lig. Ureter Inferior vesical a. Rectovaginal space Tendinous arch of levator ani Neurovascular bundle of the rectum (with the middle rectal a.) Cardinal (transverse cervical) lig. Uterosacral lig. Ovarian a. and v. Obturator a. Uterine a. Internal iliac a. and v. Mesorectal space Psoas major muscle Presacral Retrorectal space space Rectum Retroperitoneal space Parietal pelvic fascia Visceral pelvic fascia 259 Pelvis & Perineum Vagina Fig. 21.21 Location of vagina Vesicouterine pouch Midsagittal section, left lateral view. Visceral peritoneum on uterus Rectouterine pouch Body of uterus Cervix of uterus, supravaginal part Cervix of uterus, vaginal part Posterior part Urinary bladder Anterior part Vaginal fornix Vagina, posterior wall Vagina, anterior wall Rectum Urethra Rectovaginal septum Vesicovaginal septum (clinical term) Deep transverse perineal Vaginal orifice External urethral orifice Urethrovaginal sphincter Vaginal vestibule with labium minus Fig 21.22 Relationship of the vagina to the peritoneum and pelvic organs Midsagittal section, left lateral view. The vagina lies almost completely in the subperitoneal space. However, drainage of peritoneal fluid or pus from an abcess in the rectouterine space, a procedure known as culdocentecis, can be achieved through an incision in the posterior fornix. Fig. 21.23 Structure of vagina Posteriorly angled coronal section, posterior view. Posterior lip of uterine os Anterior lip of uterine os Pelvic peritoneal cavity Uterine fundus Uterine body Rectum Parietal peritoneum Peritoneum on anterior wall of rectum Visceral peritoneum on the uterus Uterine cervix Anterior vaginal column Vagina 260 Bladder Vesicouterine pouch Vaginal rugae Urethral carina Vaginal orifice External urethral orifice Symphysis Uterine os Vagina, anterior wall Rectouterine pouch Visceral peritoneum on the bladder Cervix of uterus, supravaginal part Clitoris Labium minor Vaginal vestibule Fig. 21.24 Female genital organs: Coronal section Anterior view. The vagina is both pelvic and perineal in location. It is also retroperitoneal. Internal iliac a. and v. Fundus of the uterus Rectum Sigmoid colon 21 Internal Organs Suspensory lig. of ovary Parietal peritoneum Ilium Right external iliac a. and v. Iliacus Left ovary Cardinal (transverse cervical) lig. (with sections of the uterine a. and uterine venous plexus) Left uterine tube Round lig. of uterus Pelvic retroperitoneal space Cervix with uterine os Vaginal arterial branches and venous plexus Obturator internus (with obturator fascia) Levator ani (with superior and inferior fascia of pelvic diaphragm) Vagina, posterior wall with vaginal rugae Deep transverse perineal Ischiopubic ramus Perineal membrane Crus of clitoris with ischiocavernosus Superficial perineal (Colles’) fascia Urethovaginal sphincter Perineal a. Labium majus Fig. 21.25 Vagina: Location in the perineum Transverse perineal lig. Inferior view. Labium minus Round lig. of uterus Vestibule of vagina (with vaginal orifice) Pubic symphysis A. of vestibular bulb Vestibular bulb with bulbospongiosus Deep dorsal clitoral v. Dorsal clitoral a. and n. Female urethra Inferior pubic ramus Perineal membrane Vagina Ischiocavernosus 261 Pelvis & Perineum Female External Genitalia Fig. 21.26 Female external genitalia Lithotomy position with labia minora separated. Anterior labial commissure Mons pubis Prepuce of clitoris Clitoris, glans Frenulum of clitoris External urethral orifice Labia minora Labia majora Vaginal orifice Opening of greater vestibular (Bartholin’s) glands Posterior labial commissure Perineal raphe Fig. 21.27 Vestibule and vestibular glands Lithotomy position with labia minora separated. Anus External urethral orifice Labia minora Bulbospongiosus Vaginal orifice Vestibule of vagina (space between labia minora) Bulb of vestibule Greater vestibular (Bartholin’s) gland Fig. 21.28 Erectile tissue in the female perineum Pubic tubercle Pars intermedia Body of clitoris (corpora cavernosa) Crus of clitoris Glans clitoris Urethral orifice Corpus cavernosum Pubic ramus Vaginal orifice 262 Symphysis Bulb of vestibule Greater vestibular gland Fig. 21.29 Erectile tissue and muscles of the female Lithotomy position. Removed: Labia and skin. Removed from left side: Ischiocavernosus and bulbospongiosus muscles. Body of clitoris Glans of clitoris Crus of clitoris 21 Internal Organs Prepuce of clitoris Perineal membrane Ischiocavernosus Ischial tuberosity Superficial transverse perineal Levator ani Bulbospongiosus Greater vestibular gland Bulb of vestibule Ischiocavernosus Clinical box 21.3 Episiotomy Episiotomy is a common obstetric procedure used to enlarge the birth canal during the expulsive stage of labor. The procedure is generally used to expedite the delivery of a baby at risk for hypoxia during the expulsive stage. Alternately, if the perineal skin turns white (indicating diminished blood flow), there is imminent danger of perineal laceration, and an episiotomy is often performed. More lateral incisions gain more room, but they are more difficult to repair. Bulbospongiosus Midline episiotomy Lateral episiotomy Perineum Ischiocavernosus Anus Mediolateral episiotomy Superficial transverse perineal A Types of episiotomy. Posterior commissure Levator ani External anal sphincter B Mediolateral episiotomy at height of contraction. C Pelvic floor with crowning of fetal head. 263 Pelvis & Perineum Penis, Testis & Epididymis Fig. 21.30 Penis Corona of glans Glans of penis Corpus cavernosum Corpus spongiosum Plane of section in D Superior pubic ramus Body of penis Crus of penis Obturator foramen Bulbospongiosus Ischiocavernosus Plane of section in C Ischiopubic ramus Root of penis Bulb of penis A Inferior view. Deep transverse perineal Perineal membrane Urinary bladder Urethra, prostatic part Prostatic ductules Seminal colliculus Urethra, preprostatic part Prostate Bulbourethral gland Corpus spongiosum Pubic symphysis Dorsal penile a. and n. Urethra, membranous part Deep dorsal penile v. Urethral ampulla Crus of penis Deep penile a. Corpus cavernosum Urethra, spongy part Urethra, spongy part Orifices of urethral glands Corpus cavernosum Brs. of deep penile a. Glans of penis 264 Bulbospongiosus C Cross section through the root of the penis. Navicular fossa External urethral orifice, urethral crest Longitudinal section. B Bulb of penis, corpus spongiosum Urethral a. Superficial dorsal penile v. Penile skin 21 Internal Organs Superficial penile fascia Dorsal penile a. and n. Deep penile fascia Deep dorsal penile v. Tunica albuginea of corpus cavernosum Deep penile a. Penile septum Corpus cavernosum Tunica albuginea of corpus spongiosum Urethra, spongy part DCross section through the body of the penis. Urethral a. Corpus spongiosum Fig. 21.31 Testis and epididymis Superficial fascia, deep layer Left lateral view. External spermatic fascia Internal spermatic fascia Cremaster m. and cremasteric fascia Testicular a. Pampiniform plexus (testicular vv.) Tunica dartos Tunica vaginalis, parietal layer Epididymis, body Epididymis, head Tunica vaginalis, visceral layer (on testis) Glans of penis Scrotum A Testis and epididymis in situ. Epididymis, head Epididymis, appendix Testis, appendix Epididymis, head Epididymis, body Efferent ductules Testicular a. Pampiniform plexus (testicular vv.) Tunica albuginea Epididymis, body Septum Rete testis in mediastinum testis Ductus deferens Ductus deferens Epididymis, tail Epididymis, tail Lobule B Surface anatomy of the testis and epididymis. CSagittal section of the testis and epididymis. 265 Pelvis & Perineum Male Accessory Sex Glands The accessory male sex glands consist of the seminal, prostate, and bulbourethral glands, which contribute fluid to the ejaculate that ­provides nourishment for the spermatozoa as well as neutralizes the pH of the male urethra and the vaginal environment. Fig. 21.32 Accessory sex glands Fig. 21.33 Anatomic divisions of the prostate Posterior view. The ducts of the seminal gland and ductus deferens combine to form the ejaculatory duct. Neck of bladder Prostate Urinary bladder Prostatic part Seminal colliculus Prostatic capsule Membranous part Bulbourethral gland Ureter Urethra Deep transverse perineal Spongy part Ductus deferens, ampulla A Coronal section, anterior view. Seminal gland Base Prostatic capsule Prostate Urethra Prostatic isthmus Bulbourethral glands Left lobe Urethra Ejaculatory duct orifices Apex B Sagittal section, left lateral view. Fig. 21.34 Clinical divisions of the prostate Seminal glands Right lobe C Transverse section, superior view. Ductus deferens Neck of bladder Ejaculatory duct Seminal colliculus Bladder neck Urethra A Prostate and seminal glands. Anterior zone Peripheral zone Periurethral zone 266 Urethra B Coronal section, anterior view. Plane of section in D Prostatic urethra Central zone Transition zone Bulbourethral gland C Sagittal section, left lateral view. Deep transverse perineal DTransverse section, superior view. Ejaculatory ducts Fig. 21.35 Prostate in situ Sagittal section through the male pelvis, left lateral view. Visceral peritoneum Urinary bladder, body Urinary bladder, neck Rectovesical pouch Superficial abdominal fascia, deep layer Urinary bladder, fundus Pubic symphysis Retropubic space 21 Internal Organs Urinary bladder, apex Seminal gland Superficial dorsal penile v. Rectum Superficial and deep penile fascia Ejaculatory duct Prostate Penis, corpus cavernosum Urethra, spongy part Rectoprostatic fascia Deep transverse perineal Penis, corpus spongiosum Bulbourethral gland Glans of penis Bulbospongiosus Prepuce Urethra, navicular fossa Scrotal septum Scrotum Clinical box 21.4 Prostatic carcinoma and hypertrophy Prostatic carcinoma is one of the most common malignant tumors in older men, often growing at a subcapsular location (deep to the prostatic capsule) in the peripheral zone of the prostate. Unlike benign prostatic hyperplasia, which begins in the central part of the gland, prostatic carcinoma does not cause urinary outflow obstruction in its early stages. Being in the peripheral Urinary bladder zone, the tumor is palpable as a firm mass through the anterior wall of the rectum during rectal examination. In certain prostate diseases, especially cancer, increased amounts of a protein, prostate-specific antigen or PSA, appear in the blood. This protein can be measured by a simple blood test. Rectovesical pouch Rectum Prostatic carcinoma, subcapsular A Most common site of prostatic carcinoma. B Prostatic carcinoma (arrows) with bladder infiltration. 267 22 Neurovasculature Pelvis & Perineum Overview of the Blood Supply to Pelvic Organs & Wall Fig 22.1 Branches of the right internal iliac artery Side wall of the male pelvis, left lateral view. The internal iliac artery arises from the common iliac artery. Its anterior trunk gives off visceral branches to pelvic organs and parietal branches to the pelvic wall. The posterior trunk gives off only parietal branches. Branches to the uterus and vagina in the female are the principal differences from the male vasculature. Abdominal aorta L 5 vertebra Right common iliac a. Median sacral a. Right internal iliac a. Iliolumbar a. Right external iliac a. Internal iliac a., posterior trunk Umbilical a., patent part Lateral sacral a. Superior gluteal a. Internal iliac a., anterior trunk Inferior gluteal a. Sacral plexus Obturator n. Inferior vesical a. Obturator a. Middle rectal a. Umbilical a., occluded part Coccygeus Inferior epigastric a. Obturator internus Superior vesical a. Internal pudendal a. Obturator br. of inferior epigastric a. Pudendal n. A. of ductus deferens Table 22.1 Neurovascular pathways in the pelvis There are six major neurovascular tracts on the pelvic walls, four of which (*) contain branches from the internal iliac artery. Tract Posterior ① Greater sciatic foramen, suprapiriform part* (above the piriformis) reater sciatic foramen, infrapiriform ② G part* (below the piriformis) On pelvic floor ③ Lesser sciatic foramen through pudendal canal* Superior gluteal a. and v., superior gluteal n. Inferior gluteal a. and v., inferior gluteal n., sciatic n., internal pudendal a. and v., pudendal n., posterior femoral cutaneous n. Internal pudendal a. and v., pudendal n. Lateral ④ Obturator canal* Obturator a. and v., obturator n. Anterior ⑤ Muscular lacuna (posterior to inguinal lig., lateral to iliopectineal arch) Femoral n., lateral femoral cutaneous n. ⑥ V ascular lacuna (posterior to inguinal lig., medial to iliopectineal arch) 268 Neurovascular structures transmitted Femoral a. and v., lymphatic vessels (the femoral a. is a branch of the external iliac a.), femoral branch of genitofemoral n. ① ⑤ Piriformis ② Inguinal lig. ⑥ Iliopectineal arch ④ Obturator membrane Sacrospinous lig. Sacrotuberous lig. ③ External iliac a. Internal iliac a. Right common iliac v. Inferior vena cava Right internal iliac v. ② ① ③ ④ A. of ductus deferens Superior vesical a. ③ ⑨ ⑥ Right external iliac v. ④ Dorsal penile a. ⑨ ⑧ ⑥ ⑦ Deep dorsal penile v. Inferior rectal a. Posterior scrotal brs. A Male pelvis. ⑧ ⑤ ⑦ ⑤ ② Vv. of penile bulb Deep penile vv. Inferior rectal vv. Posterior scrotal vv. A Male pelvis. Abdominal aorta Left common iliac a. Left external iliac a. Left internal iliac a. Right internal iliac a. Inferior vena cava Right internal iliac v. ② Left ureter Piriformis ⑨ ⑤ Coccygeus ④ ① Uterine vv. ⑥ Inferior rectal a. B Female pelvis. Table 22.2 ② Uterine a. Vaginal a. ⑧ ⑦ ⑦ ⑧ ③ Right external iliac v. ④ ⑤ ⑥ ⑩ Branches of the internal iliac artery The internal iliac artery gives off five parietal (pelvic wall) and four visceral (pelvic organs) branches.* Parietal branches are shown in italics. Branches ① liolumbar a. ② Superior gluteal a. ③ Lateral sacral a. ④ Umbilical a. ⑤ B Female pelvis. Table 22.3 Venous drainage of the pelvis Tributaries ① Superior gluteal v. ② Lateral sacral v. ③ Obturator vv. Obturator a. ④ Vesical vv. ⑥ Inferior vesical a. ⑤ Vesical venous plexus ⑦ Middle rectal a. ⑥ Middle rectal vv. (rectal venous plexus) (also superior and inferior rectal vv., not shown) ⑧ Internal pudendal a. ⑦ Internal pudendal v. ⑧ Inferior gluteal vv. ⑨ Prostatic venous plexus ⑩ Uterine and vaginal venous plexus A. of ductus deferens Superior vesical a. Inferior rectal a. Dorsal penile a. Posterior scrotal aa. ⑨ 22 Neurovasculature ① Inferior gluteal a. * In the female pelvis, the origin of the uterine and vaginal arteries is highly variable. The male pelvis also contains veins draining the penis and scrotum. 269 Pelvis & Perineum Arteries & Veins of the Male Pelvis Fig 22.2 Blood vessels of the male pelvis Right hemipelvis, left lateral view. Abdominal aorta Inferior mesenteric a. Left common iliac a. and v. Median sacral a. Right internal iliac a. and v. Umbilical a. Right iliolumbar a. Right ureter Right lateral sacral v. Right external iliac a. and v. Right inferior gluteal a. and v. Superior rectal a. and v. (from/to inferior mesenteric a. and v.) Right obturator a. and v. Internal pudendal a. and v. Right superior vesical a. and v. Right inferior vesical a. and v. Right ductus deferens and a. Right middle rectal a. and v. Left ureter Seminal gland Left superior and inferior vesical a. and v. Left middle rectal a. and v. Dorsal penile a., deep dorsal penile v. Prostate Left inferior rectal a. and v. Spermatic cord Left internal pudendal a. and v. Perineal a. and v. Posterior scrotal a. and v. 270 Fig 22.3 Blood vessels of the male genitalia Opened: Inguinal canal and coverings of the spermatic cord Iliacus Psoas major Right ureter Testicular a. and v. Internal iliac a. and v. External iliac a. and v. Sacral plexus Umbilical a. Inguinal lig. Inferior epigastric a. and v. Rectum Saphenous opening Urinary bladder External pudendal a. and v. Femoral a. and v. Suspensory lig. of penis Pampiniform plexus (testicular vv.) Left ductus deferens Dorsum of penis Right ductus deferens Dorsal penile a., deep dorsal penile v. Internal spermatic fascia Testis Epididymis Glans of penis Clinical box 22.1 Fig 22.4 Blood vessels of the testis Left lateral view. Pampiniform plexus (testicular vv.) 22 Neurovasculature Deep circumflex iliac a. and v. Asymmetric venous drainage of the testes Testicular a. The pampiniform plexus has an important cooling affect on the testis. Because drainage of the left testicular vein into the left renal vein is at a right angle, a physiological constriction may occur that can obstruct outflow from the testicular vein. This can result in enlargements, or “varicoceles,” of the left testicular vein and pampiniform plexus, which can disrupt the cooling function of the plexus and the fertility of the testis. A. of ductus deferens Left renal v. Vv. of ductus deferens Cremasteric a. and v. Inferior vena cava Left testicular v. Inguinal canal Testicular vv. (pampiniform plexus) 271 Pelvis & Perineum Arteries & Veins of the Female Pelvis Fig 22.5 Blood vessels of the female pelvis Right hemipelvis, left lateral view. Right common iliac a. Right ovarian a. and v. (in ovarian suspensory lig.) Right umbilical a. Right ureter Right superior vesical a. Right ovary and uterine tube Right internal iliac a. Median sacral a. Right iliolumbar a. Internal iliac a. and v., anterior division Right uterine a. and v. Right inferior vesical a., vesical v. Superior rectal a. and v. Right vaginal a. Right obturator a. and v. Right external iliac a. and v. Right round lig. of uterus Left superior vesical a., vesical v. Left ureter Deep dorsal clitoral v. Right middle rectal a. and v. Uterine venous plexus Left uterine a. and v. Vaginal venous plexus Left middle rectal a. and v. Left inferior vesical a., vesical v. Left inferior rectal a. and v. Left internal pudendal a. and v. Perineal a. and v. 272 Fig 22.6 Blood vessels of the female genitalia Left ureter Left ovarian a. and v. Abdominal aorta Inferior mesenteric a. Inferior vena cava Left common iliac a. and v. Median sacral a. and v. Left internal iliac a. and v. Left external iliac a. and v. Rectum Uterine a., tubal br. Uterine tube 22 Neurovasculature Removed: peritoneum on left side; Retracted: uterus. Ovary Fundus of uterus Umbilical a., patent part Middle rectal a. Obturator a., v., and n. Uterine a. and v. Round lig. of uterus Inferior vesical a. Vaginal a. Superior vesical a., vesical v. Mesometrium (of broad lig. of uterus) Umbilical a., obliterated part Urinary bladder Visceral peritoneum on urinary bladder Urinary bladder Uterus, fundus Visceral peritonium on posterior surface of uterus Obturator a. Round lig. of uterus Superior vesical a. Fig 22.7 Relationship of the uterine artery and ureter The uterine artery runs in the broad ligament to the uterus. The ureter passes inferior to the artery lateral to the cervix. Thus the ureter is at risk for injury during uterine surgery. Broad lig. External iliac a. and v. Uterine tube Ovary Uterine a. Inferior vescial a. Left ureter Right ureter Internal iliac a. and v. Rectouterine fold Rectum Common iliac a. Uterus Rectum Left ureter A Superior view of the pelvis. Bladder B Left lateral view of left ureter and left uterine artery. Left uterine a. Vaginal br. 273 Pelvis & Perineum Arteries & Veins of the Rectum & External Genitalia Fig. 22.8 Blood vessels of the rectum Posterior view. The superior rectal arteries are the main blood supply to the rectum; the middle rectal arteries serve as an anastomosis between the superior and inferior rectal arteries. Similarly, the middle rectal To portal v. Inferior mesenteric a. and v. veins provide an important portocaval collateral pathway between the superior and inferior rectal veins. Abdominal aorta Inferior vena cava Median sacral a. and v. Right common iliac a. and v. Sigmoid aa. and vv. Superior rectal a. and v. Right superior gluteal a. and v. Left external iliac a. and v. Right internal iliac a. and v. Left obturator a. Right obturator v. Left inferior gluteal a. Right inferior gluteal v. Left middle rectal a. Right middle rectal v. Left internal pudendal a. Left inferior rectal a. Rectal venous plexus Levator ani Right inferior rectal v. Right internal pudendal v. Fig. 22.9 The hemorrhoidal plexus Longitudinal section of the anal canal with the hemorrhoidal plexus windowed. The hemorrhoidal plexus, supplied by branches of the superior rectal artery, is a permanently distended cavernous body that forms circular cushions in the area of the anal columns. When filled with blood, these cushions serve as an effective continence mechanism that ensures liquid and gas-tight closure. The sustained contraction of the muscular sphincter apparatus inhibits venous drainage, but when the sphincter relaxes during defecation, blood is allowed to drain via arteriovenous anatomoses to the inferior mesenteric vein and middle and inferior rectal veins. 274 Muscularis mucosae of the anal canal Hemorrhoidal plexus Superior rectal a. and v. Puborectalis Transsphincteric vv. Pectinate line External anal sphincter Anal pecten Rectal vv. of external venous plexus Proctodeal gland Femoral a. and v. External pudendal a. and v. 22 Neurovasculature Fig. 22.10 Neurovasculature of the penis and scrotum Superficial inguinal ring Ilioinguinal n. External spermatic fascia External pudendal a. and v. Deep dorsal penile v. Suspensory lig. of penis Dorsal penile a. and n. Anterior scrotal a. and v. Deep penile fascia Tunica albuginea Superficial dorsal penile vv. Superficial dorsal penile vv. Deep dorsal penile v. Deep penile fascia Dorsal penile a. and n. Corona of glans Superficial penile fascia Glans, penis B Dorsal vasculature of the penis. Removed from left side: Deep penile fascia. A Anterior view. Partially removed: Skin and fascia. Fig. 22.11 Blood vessels of the female external genitalia Inferior view. Dorsal clitoral a. Deep clitoral a. A. of vestibular bulb Posterior labial brs. Crus of clitoris Vestibular bulb Superficial transverse perineal Perineal a. Internal pudendal a. A Arterial supply. Inferior rectal a. Deep dorsal clitoral v. Deep clitoral vv. Venous plexus of vestibular bulb V. of vestibular bulb Posterior labial vv. Perineal vv. Internal pudendal v. Inferior rectal vv. B Venous drainage. 275 Pelvis & Perineum Lymphatics of the Pelvis Table 22.4 Lymph nodes of the pelvis are distributed along major blood vessels and anterior to the sacrum. Lymph from pelvic organs can drain to one or more of several groups of lymph nodes (inguinal, internal iliac, external iliac, sacral or common iliac) before passing to the preaortic or lateral aortic nodes. Lymph from the perineum may drain first to superficial or deep inguinal nodes before draining to the external iliac nodes. Note that the testes and ovaries drain directly to lateral aortic nodes. ① ④ Lymph nodes of the pelvis ③ ② ⑤ Preaortic l.n. ① Superior mesenteric l.n. ② Inferior mesenteric l.n. ③ Left lateral aortic l.n. ④ Right lateral aortic (caval) l.n. ⑩ ⑥ ⑦ ⑤ Common iliac l.n. ⑥ Internal iliac l.n. Horizontal group Vertical group ⑨ ⑦ External iliac l.n. ⑧ ⑧ Superficial inguinal l.n. Horizontal group Vertical group ⑨ Deep inguinal l.n. ⑩ Sacral l.n. Fig 22.12 Lymphatic drainage of the rectum Anterior view. Three zones of the rectum drain to different groups of lymph nodes. The upper zone drains to inferior mesenteric nodes. The middle zone and columnar part of the lower zone drains to internal iliac nodes. The cutaneous part of the lower zone drains to superficial inguinal nodes. Abdominal aorta Fig 22.13 Lymphatic drainage of the bladder and urethra Anterior view. Different parts of the bladder drain to internal iliac or ­external iliac nodes or directly to the common iliac nodes. The urethra, as well as the penis in the male, is drained by superficial and deep inguinal nodes. Inferior mesenteric a. and l.n. Superior rectal a. Common iliac a. Internal iliac a. and l.n. Superficial inguinal l.n. 276 Common iliac l.n. Internal iliac l.n. Superficial and deep inguinal l.n. External iliac l.n. Fig 22.14 Lymphatic drainage of the male genitalia Prostate – drain along multiple pathways including to external iliac, internal iliac, and sacral nodes Testis and epididymis – drain via a direct pathway along the testicular vessels to the right and left lumbar lymph nodes. Some lymph from the epididymis may drain first to internal iliac nodes. Scrotum and coverings of the testes – drain to superficial inguinal nodes Ductus deferens and seminal glands – drain to external iliac ­(primarily) and internal iliac nodes. Abdominal aorta Lateral aortic l.n. Lumbar l.n. 22 Neurovasculature Male pelvis, anterior view. Male genitalia drain to the lumbar lymph nodes via several pathways: Testicular a. Internal iliac l.n. Sacral l.n. External iliac l.n. A Lymphatic drainage of the prostate, epididymis, ductus deferens and testes. Lymphatic drainage from the testis and epididymis Superficial inguinal l.n. Lymphatic drainage from the scrotum and coverings of the testis Femoral a. B Lymphatic drainage of the testes and scrotum. Fig 22.15 Lymphatic drainage of the female genitalia Female pelvis, anterior view. Female genitalia drain to the lumbar lymph nodes via several pathways: Uterine cervix, middle and upper part of vagina – drain to deep inguinal nodes Ovary, uterine fundus and distal part of uterine tube – drain via a direct pathway along the ovarian vessels to right and left lumbar lymph nodes. External genitalia (except anterior clitoris) – drain to superficial i­ nguinal nodes Uterine fundus and body, and proximal part of uterine tube – drain to internal iliac, external iliac, and sacral nodes. Body and glans of the clitoris – drain to deep inguinal and internal iliac nodes Lymphatic drainage of the anterior clitoris Inferior vena cava Right lateral aortic (caval) l.n. Right common iliac a. Abdominal aorta Internal iliac lymph nodes Left lateral aortic l.n. Common iliac l.n. Internal iliac l.n. Sacral l.n. Superficial inguinal l.n. (horizontal group) External iliac l.n. Deep inguinal l.n. Superficial inguinal l.n. Deep inguinal l.n. Superficial inguinal l.n. (vertical group) A Lymphatic drainage of the ovary, uterus, uterine tube, vagina, and labia. B Lymphatic drainage of the clitoris. 277 Pelvis & Perineum Lymph Nodes of the Genitalia Fig. 22.16 Lymph nodes of the male genitalia Anterior view. Removed: Gastrointestinal tract (except rectal stump) and peritoneum. Left lumbar l.n. Right lumbar l.n. Inferior mesenteric l.n. Intermediate lumbar l.n. Common iliac l.n. Abdominal aorta Promontory l.n. Sacral l.n. External iliac l.n. External iliac a. Rectum Urinary bladder Superficial inguinal l.n., horizontal group Deep inguinal l.n. Superficial inguinal l.n., vertical group Epididymis Testis Penis Scrotum 278 Fig. 22.17 Lymph nodes of the female genitalia Anterior view. Removed: Gastrointestinal tract (except rectal stump) and peritoneum. Retracted: Uterus. Inferior mesenteric l.n. Common iliac l.n. Promontory l.n. Rectum Sacral l.n. Uterine tube 22 Neurovasculature Intermediate lumbar l.n. Internal iliac l.n. Ovary External iliac l.n. Uterus Obturator l.n. Mesometrium Superficial inguinal l.n., horizontal group Intermediate lacunar l.n. Urinary bladder Superficial inguinal l.n., vertical group Deep inguinal l.n. Fig. 22.18 Lymphatic drainage of the pelvic organs Thoracic duct Right lumbar trunk Cisterna chyli Left lumbar trunk Right lumbar l.n. Left lumbar l.n. Lateral caval l.n. Lateral aortic l.n. Intermediate lumbar l.n. Precaval l.n. Preaortic l.n. Retrocaval l.n. Lacunar l.n. (lateral, medial, and intermediate) Deep inguinal l.n. Retroaortic l.n. External iliac l.n. Common iliac l.n. Internal iliac l.n. Obturator l.n. Subaortic l.n. Sacral l.n. Lateral, medial, and intermediate external iliac l.n. Promontory l.n. Superior and inferior gluteal l.n. Interiliac l.n. Lateral, medial, and intermediate common iliac l.n. Visceral pelvic l.n. Superficial inguinal l.n. Pararectal l.n. Parauterine l.n. Paravaginal l.n. Lateral vesical l.n. Pre- and retrovesical l.n. 279 Pelvis & Perineum Autonomic Innervation of the Genital Organs Fig 22.19 Innervation of the male pelvis Intermesenteric plexus Inferior mesenteric plexus Sympathetic trunk, lumbar ganglia Lumbar splanchnic nn. Gray ramus communicans Ureteral plexus Lumbar nn., anterior rami L5 vertebra Superior hypogastric plexus Lumbosacral trunk Right hypogastric n. Left hypogastric n. Iliac plexus Pelvic splanchnic nn. Obturator n. Middle rectal plexus Pudendal n. Deferential plexus Seminal gland Inferior rectal plexus Vesical plexus Inferior rectal nn. Prostatic plexus Cavernous nn. of penis Sympathetic trunk Lesser splanchnic n. (T10-T11) Least splanchnic n. (T12) Lumbar splanchnic n. (L1-L2) Superior mesenteric ganglion Renal ganglion Dorsal n. of the penis Posterior scrotal nn. A Right pelvis, left lateral view. Intermesenteric plexus Inferior mesenteric ganglion Superior hypogastric plexus Pelvic splanchnic nn. (S2-S4) Inferior hypogastric plexus ** Sacral splanchnic nn. (S1-S4) Parasympathetic postganglionic fibers Seminal vesicle Prostate with prostatic plexus Ductus deferens with deferential plexus 280 Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Bladder with vesical plexus Testicular plexus Sympathetic preganglionic fibers Epididymis, testes **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus B Schematic of innervation of male genitalia. Fig 22.20 Innervation of the female pelvis Intermesenteric plexus Sympathetic trunk, lumbar ganglia Lumbar splanchnic nn. Gray ramus communicans Ureteral plexus Lumbar nn., anterior rami L5 vertebra Left hypogastric n. Superior hypogastric plexus 1st sacral n., anterior ramus Right hypogastric n. 22 Neurovasculature Inferior mesenteric plexus Lumbosacral trunk Ovarian plexus Obturator n. Sacral plexus Right inferior hypogastric plexus Pelvic splanchnic nn. Vesical plexus Pudendal n. Right uterovaginal plexus Right middle rectal plexus Sympathetic trunk A Right pelvis, left lateral view. Lesser splanchnic n. (T10-T11) Least splanchnic n. (T12) Celiac ganglion Renal ganglion Superior mesenteric ganglion Lumbar splanchnic n. (L1-L2) Intermesenteric plexus Inferior mesenteric ganglion Pelvic splanchnic nn. (S2-S4) Superior hypogastric plexus Sacral splanchnic nn. (S1-S4) Hypogastric nn. **Inferior hypogastric plexus Uterovaginal plexus Ovarian plexus Uterus Uterine tube Vagina Sympathetic preganglionic fibers Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus. Ovary Schematic of innervation of female B genitalia. 281 Pelvis & Perineum Autonomic Innervation of the Urinary Organs & Rectum Fig 22.21 Innervation of the pelvic urinary organs See pp. 215 and 217 for innervation of the kidneys and upper ureters. Intermesenteric plexus Inferior mesenteric ganglion Sympathetic trunk, lumbar ganglia Ureteral plexus Testicular plexus Inferior mesenteric plexus Superior hypogastric plexus Iliac plexus Left hypogastric n. Sympathetic trunk, sacral ganglia Right hypogastric n. 1st sacral n., anterior ramus Sympathetic trunk Inferior hypogastric plexus Pelvic splanchnic nn. Middle rectal plexus Vesical plexus Lumbar splanchnic n. (L1-L2) Sympathetic trunk Prostatic plexus Inferior mesenteric ganglion Sacral Lumbar splanchnic n. splanchnic nn. (L1-L2) A Anterior view of male pelvis (S1-S4) and lower abdomen. Inferior mesenteric ganglion Sacral splanchnic nn. (S1-S4) Sympathetic trunk Superior hypogastric plexus Lumbar splanchnic n. (L1-L2) Superior hypogastric plexus Sympathetic preganglionic fibers Seminal Pelvic splanchnic Sympathetic postganglionic fibers vesicle nn. (S2-S4) Parasympathetic preganglionic fibers **Inferior hypoParasympathetic postganglionic fibers gastric plexus Ureter (abdominal and pelvic parts) Vesical plexus Prostate Sympathetic preganglionic fibers Ureteral plexus Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Bladder Vesical plexus Sympathetic preganglionic fibers 282 Sympathetic postganglionic fibers Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Prostate **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus. Ureteral plexus Prostate **Minimal sympathetic preganglionic traveling through the sacral splanchn will synapse in the ganglia located in inferior hypogastric plexus. **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus. Seminal vesicle Pelvic splanchnic nn. (S2-S4) **Inferior hypogastric plexus Ureter (abdominal and pelvic parts) Ureter (abdominal and pelvic parts) Pelvic splanchnic nn. (S2-S4) Ureteral plexus **Inferior hypogastric plexus Bladder Vesical plexus Inferior mesenteric ganglion Sacral splanchnic nn. (S1-S4) Superior hypogastric plexus B Schematic of the urinary bladder and ureter. Fig 22.22 Innervation of the anal sphincter mechanism 22 Neurovasculature Sympathetic trunk L 5 vertebra Lumbar splanchnic nn. Superior hypogastric plexus Sacral plexus Branches from S2– S4 L 5 vertebra Pudendal n. Sacral splanchnic nn. Rectum Levator ani muscle Superficial and deep parts Inferior rectal nn. Subcutaneous part Cutaneous zone Inferior hypogastric plexus External anal sphincter Internal anal sphincter A Somatomotor and somatosensory innervation: The pudendal nerves and inferior rectal branches provide active, partly voluntary innervation of the external anal sphincter and levator ani muscles, and sensation for the anus and perianal skin. Sacral plexus Pelvic splanchnic nn. Rectal plexus Rectum Internal anal sphincter Visceromotor and viscerosensory innervation: Pelvic B splanchnic nerves (S2-4) innervate the internal anal sphincter, which helps to maintain closure of the anal canal. They also supply sensation to the wall of the rectum, particularly the stretch receptors in the rectal ampulla, which when stretched trigger an awareness of the need to defecate. Clinical box 22.2 Mechanism of defecation (after Wedel) Both defecation and continence are under central nervous system control involving such diverse structures as the cerebral cortex, muscles of the abdomen and pelvis and perianal skin. Filling of the rectal ampulla and stimulation of local stretch receptors in the ampullary wall. When the fecal bolus is propelled into the ampulla, mechanoreceptors detect distension and transmit the information to the sensory cortex, which perceives the urge to defecate. Rectoanal inhibitory reflex and relaxation of the voluntary innervated sphincters. When the ampulla fills, the intrarectal pressure increases and the internal anal sphincter relaxes. This is followed by voluntary relaxation of the puborectalis sling and the external anal sphincter, which results in the straightening of the anorectal angle and widening of the anal canal. Propulsion of the fecal column. Rectal evacuation is assisted by a direct involuntary increase in pressure in the rectal area and by simultaneous increase in pressure by the contraction of voluntarily innervated muscles in the abdomen wall, pelvic floor, and diaphragm. With propulsion of the fecal column, the hemorrhoidal cushions are drained and pushed out. Completion of defecation. After the sphincter apparatus allows the fecal column to pass through, it comes in contact with the highly sensitive anoderm, which perceives the volume, consistency and location of the stool. This perception initiates the voluntary process of completing defecation, which is marked by the contraction of the sphincter apparatus and filling of the hemorrhoidal plexus. 283 Neurovasculature of the Male & Female Perineum Pelvis & Perineum Fig. 22.23 Nerves of the male perineum and genitalia Scrotum Bulbospongiosus Lithotomy position. Ilioinguinal n. and genitofemoral n., genital br. Posterior scrotal nn. (brs. of pudendal n.) Pudendal n. Posterior femoral cutaneous n. Dorsal n. of penis (br. of pudendal n.) Superficial transverse perineal Gracilis Inferior clunial nn. Adductor magnus Posterior femoral cutaneous n. Pudendal n. Ilioinguinal n. and genitofemoral n., genital br. Ischial tuberosity Pudendal n. Perineal nn. (brs. of pudendal n.) Posterior femoral cutaneous n. Anococcygeal nn. of penis endal n.) Middle clunial nn. Anus Superior clunial nn. ioernosus External anal sphincter Inferior clunial nn. Adductor magnus Fig. 22.24 Neurovasculature male perineum Posterior femoral of the cutaneous n. Lithotomy position. from left side: PudendalRemoved n. Perineal membrane, Ischial bulbospongiosus, and tuberosity root of penis. Perineal nn. (brs. of pudendal n.) Corpus spongiosum Corpora cavernosa Levator ani Gluteus maximus Deep dorsal penile v. Arcuate pubic lig. Transverse perineal lig. Spermatic cord Bulbospongiosus Dorsal penile a. Dorsal penile n. Posterior scrotal nn. Muscular brs. Perineal nn. Bulbourethral gland Anus Inferior rectal nn. External anal sphincter Gluteus maximus 284 Inferior rectal nn. (br. of pudendal n.) Middle clunial nn. Superior clunial nn Ischiocavernosus Perineal body Anococcygeal nn. Ischial tuberosity Internal pudendal a. and v. Pudendal n. Inferior rectal a. and v. Posterior femoral cutaneous n. Middle clunial nn. clunial nn. Fig. 22.25 Nerves ofSuperior the female perineum and genitalia Inferior clunial nn. External urethral orifice Glans of clitoris Bulbospongiosus Dorsal clitoral n. (br. of pudendal n.) Posterior labial nn. (br. of pudendal n.) Gracilis Labium minus Ischiocavernosus Vaginal orifice Perineal membrane Superficial transverse perineal Adductor magnus Perineal body 22 Neurovasculature Sensory innervation of the female perineum. Lithotomy position. Anococcygeal nn. Posterior femoral cutaneous n., perineal brs. Perineal nn. (brs. of Ilioinguinal n. and pudendal n.) genitofemoral n., genital br. and labial br. Posterior femoral cutaneous n. Ischial tuberosity Pudendal n. Posterior femoral cutaneous n. Pudendal n. Middle clunial nn. Superior clunial nn. Inferior clunial nn. External urethral orifice Anus Glans of clitoris Bulbospongiosus External anal sphincter Anococcygeal nn. Dorsal clitoral n. (br. of pudendal n.) Inferior rectal nn. (brs. of pudendal n.) Levator ani Gluteus Inferior Posterior labial nn. maximus clunial nn. (br. of pudendal n.) Gracilis Labium minus Fig. 22.26 Neurovasculature of the female perineum Vaginal orifice Lithotomy position. Removed fromSuperficial left side: transverse Bulbospongiosus and perineal ­ischiocavernosus. Bulbospongiosus Vestibular bulb Ischiocavernosus Crus of clitoris Perineal membrane Ischiocavernosus Dorsal clitoral a. and n. Adductor magnus Anterior labial nn. Posterior femoral cutaneous n., perineal brs. Deep clitoral a. Posterior femoral cutaneous n. A. of vestibular bulb Ischial tuberosity Perineal body Perineal a. Perineal nn. (brs. of pudendal n.) Superficial transverse perineal Pudendal n. Posterior labial nn. Ischial tuberosity Inferior rectal a. and v. Anus External anal sphincter Inferior rectal nn. (brs. of pudendal n.) Levator ani Gluteus maximus Inferior clunial nn. Pudendal n. Internal pudendal a. and v. Greater vestibular gland Perineal membrane Perineal nn. Inferior rectal nn. Levator ani 285 Pelvis & Perineum 23 Sectional & Radiographic Anatomy Sectional Anatomy of the Pelvis & Perineum Femoral a., v., and n. Pubis Urinary bladder Fig. 23.1 Female pelvis Pectineus Transverse section through the bladder and cervix of the uterus. Inferior view. Iliopsoas Obturator canal (inlet) Head of femur Lig. of head of femur Obturator internus Left ureter (cut obliquely) Cervix of uterus Uterovaginal venous plexus Sciatic n. Ischial spine Rectum Gluteus maximus Sacrospinous lig. Fig. 23.2 Male pelvis Transverse section through the bladder and seminal glands. Inferior view. Coccyx Rectouterine pouch Rectus abdominis Ductus deferens Uterosacral lig. Urinary bladder Orifice of right ureter Femoral a., v., and n. Iliopsoas Head of femur Obturator a., v., and n. Seminal gland Rectovesical septum Rectum Sciatic n. Gluteus maximus Inferior vesical a. Vesicoprostatic venous plexus Inferior hypogastric plexus Obturator internus Ischial spine Sacrospinous lig. Coccyx 286 Transverse section through the prostate gland and anal canal. Inferior view. Corpora cavernosa of penis Femoral a., v. and n. Spermatic cord Adductor mm. Inferior pubic ramus Prostatic urethra Pubic symphysis Levator ani 23 Sectional & Radiographic Anatomy Fig. 23.3 Male pelvis Obturator externus Prostate Obturator membrane Seminal gland Rectoprostatic fascia Rectum Ischial tuberosity Sciatic n. Obturator internus Gluteus maximus Ischioanal fossa Pudendal n., internal pudendal a. and v. 287 Pelvis & Perineum Radiographic Anatomy of the Female Pelvis Fig 23.4 MRI of the female pelvis Symphysis Transverse section, inferior view. Femoral a. Femoral v. Uterine body Bladder Round lig. Follicle Follicle A B C Ovary Acetabulum Proper ovarian lig. Ovary Sigmoid colon Iliac vessels A Section through the body of the uterus. (Reproduced from Krombach GA, Mahnken AH. Body Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) Sacrum Bladder Cervix Head of femur Rectouterine pouch Obturator internus Gluteus maximus Rectum Coccyx Sartorius Femoral a., v., and n. Urethra B Section through the cervical canal. The image shows the low-signal intensity cervical stroma (arrows), which surrounds the narrow highsignal intensity cervical canal. (Reproduced from Hamm B. et al. MRT von Abdomen und Becken, 2nd ed. Stuttgart: Thieme; 2006.) Pubic symphysis Pubis (body) Pectineus Rectus femoris Levator ani Iliopsoas Femur Obturator externus Sciatic n. C Section through the lower vagina. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) 288 Ischial tuberosity Gluteus maximus Vagina Rectum Obturator internus Fig. 23.5 MRI of the female pelvis Cervical canal Sagittal section, left lateral view Myometrium Coccyx Bladder A Position of the uterus with a near empty bladder. The image shows the uterus in the first half of the menstrual cycle (proliferative phase) with narrow endometrium and relatively low-signal intensity of the mymoetrium. (Reproduced from Hamm B. et al. MRT von Abdomen und Becken, 2nd ed. Stuttgart: Thieme; 2006.) Urethra Levator ani Pubic symphysis External anal sphincter Vagina 23 Sectional & Radiographic Anatomy Rectum Endometrium Body of uterus (myometrium) Uterus (junctional zone) Uterus (cavity) Uterus (endometrium) Rectum Rectouterine pouch (of Douglas) Urinary bladder Urethra Vagina (wall) B Position of the uterus with a full bladder. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Pubis Fig. 23.6 MRI of the female pelvis Coronal section, anterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Psoas major L4 vertebra Iliac crest Sigmoid colon Iliacus Internal iliac a. and v. Gluteus medius Uterus Head of femur Urinary bladder Obturator internus Levator ani Ischium, ramus Labium minus 289 Pelvis & Perineum Radiographic Anatomy of the Male Pelvis Fig. 23.7 MRI of the male pelvis Sagittal section, left lateral view. (Reproduced from Hamm B. et al. MRT von Abdomen und Becken, 2nd ed. Stuttgart: Thieme; 2006.) Rectus abdominis Prostate Seminal gland Sacrum Rectovesical (Denonvillier) fascia Bladder Ampulla of rectum Pubic symphysis Corpus cavernosum of penis Anal canal Corpus spongiosum of penis Bulb of penis Fig. 23.8 MRI of the testes Pubis Pubic symphysis Spermatic cord Mediastinum testis with rete testis Spermatic cord Corpus cavernosum of penis Urethra Mediastinum of testis Tunica albuginea Corpus spongiosum of penis Testes A Coronal section, anterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) 290 Head of the epididymis Tunica albuginea Tail of the epididymis B Parasagittal section, T2 W image. (Reproduced from Krombach GA, Mahnken AH. Body Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) Fig. 23.9 MRI of the prostate (Reproduced from Krombach GA, Mahnken AH. Body Imaging: Thorax and Abdomen. New York, NY: Thieme; 2018.) Pubis 23 Sectional & Radiographic Anatomy Anterior fibromuscular connective tissue Transitional zone Prostatic urethra Ductus deferens Seminal glands Transitional zone Peripheral zone Coil inside rectum A Transverse section, T2W image. Obturator internus muscle Urethra Peripheral zone B Coronal section, T2W image. Fig. 23.10 MRI of the male pelvis Coronal section. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Common iliac a. and v. Sigmoid colon Urinary bladder Head of femur Obturator externus muscle Pubis Corpus spongiosum Bulbospongiosus muscle Prostate (central zone) Prostate (peripheral zone) Prostate (transition zone) Ureter Corpus cavernosum Ischiocavernosus muscle 291 Upper Limb 24 Surface Anatomy 28 Neurovasculature Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 25 Shoulder & Arm Bones of the Upper Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clavicle & Scapula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Humerus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Shoulder: Glenohumeral Joint . . . . . . . . . . . . . . Subacromial Space & Bursae . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Muscles of the Shoulder & Arm (I) . . . . . . . . . . . . . . Anterior Muscles of the Shoulder & Arm (II) . . . . . . . . . . . . . Posterior Muscles of the Shoulder & Arm (I) . . . . . . . . . . . . . Posterior Muscles of the Shoulder & Arm (II) . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (IV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 298 300 302 304 306 308 310 312 314 316 318 320 322 26 Elbow & Forearm Radius & Ulna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elbow Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments of the Elbow Joint . . . . . . . . . . . . . . . . . . . . . . . . . Radioulnar Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Forearm: Anterior Compartment . . . . . . . . . Muscles of the Forearm: Posterior Compartment . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 326 328 330 332 334 336 338 340 27 Wrist & Hand Bones of the Wrist & Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . Carpal Bones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Wrist & Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments & Compartments of the Wrist . . . . . . . . . . . . . . . Ligaments of the Fingers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Hand: Superficial & Middle Layers . . . . . . . . . Muscles of the Hand: Middle & Deep Layers . . . . . . . . . . . . . Dorsum of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 344 346 348 350 352 354 356 358 360 362 Arteries of the Upper Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . Veins & Lymphatics of the Upper Limb . . . . . . . . . . . . . . . . . Nerves of the Upper Limb: Brachial Plexus . . . . . . . . . . . . . . Supraclavicular Branches & Posterior Cord . . . . . . . . . . . . . . Posterior Cord: Axillary & Radial Nerves . . . . . . . . . . . . . . . . Medial & Lateral Cords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Median & Ulnar Nerves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superficial Veins & Nerves of the Upper Limb . . . . . . . . . . . . Posterior Shoulder & Arm . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Axilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anterior Arm & Cubital Region . . . . . . . . . . . . . . . . . . . . . . . . Anterior & Posterior Forearm . . . . . . . . . . . . . . . . . . . . . . . . . Carpal Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Palm of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dorsum of the Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364 366 368 370 372 374 376 378 380 382 384 386 388 390 392 394 29 Sectional & Radiographic Anatomy Sectional Anatomy of the Upper Limb. . . . . . . . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (I). . . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (II). . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (III). . . . . . . . . . . . Radiographic Anatomy of the Upper Limb (IV) . . . . . . . . . . . 396 398 400 402 404 24 Surface Anatomy Upper Limb Surface Anatomy Fig. 24.1 Regions of the upper limb Clavipectoral triangle Deltoid region Deltoid region Infraclavicular fossa Clavipectoral triangle Axillary region Infraclavicular fossa Anterior arm region Scapular region Posterior arm region Axillary region (axillary fossa) Anterior cubital region Posterior cubital region Anterior forearm region B Right axilla, anterior view. Posterior forearm region Anterior carpal region Posterior carpal region Palm of the hand Dorsum of the hand A Right limb, anterior view. CRight limb, posterior view. Fig. 24.2 Palpable musculature of the upper limb Clavicle Scapular spine Deltoid Cephalic v. (in deltopectoral groove) Pectoralis major Biceps brachii Deltoid Teres major Basilic v. Triceps brachii Cephalic v. Olecranon Median cubital v. Extensor carpi radialis longus Brachioradialis Flexor carpi radialis Flexor carpi ulnaris Hypothenar eminence A Left limb, anterior view. 294 Long head Lateral head Latissimus dorsi Palmaris longus tendon Thenar eminence Basilic v. Extensor carpi ulnaris Flexor carpi ulnaris Extensor digitorum tendons, dorsal venous network BRight limb, posterior view. Extensor carpi radialis longus Cephalic v. Extensor digitorum Fig. 24.3 Palpable bony prominences of the upper limb Coracoid process Acromion Greater tubercle Greater and lesser tubercles Scapular spine Inferior angle Medial epicondyle Lateral epicondyle Olecranon 24 Surface Anatomy Except for the lunate and trapezoid bones, all of the bones in the upper limb are palpable to some degree through the skin and soft tissues. Superior angle Clavicle Acromion Head of radius Shaft of ulna Tubercle of scaphoid DIP, distal interphalangeal; IP, interphalangeal; MCP, metacarpophalangeal; PIP, proximal interphalangeal. Styloid process of radius Triquetrum bone Hook of hamate Tubercle of trapezium Fig. 24.4 Surface anatomy of the wrist and hand Styloid process of ulna Pisiform bone Capitate bone Metacarpophalangeal joints Metacarpals Phalanges Interphalangeal joints B Right limb, posterior view. A Right limb, anterior view. DIP joint crease PIP joint crease MCP joint crease Distal transverse crease Proximal transverse crease IP joint crease Middle crease MCP joint crease Hypothenar eminence Pisiform Thenar eminence Thenar crease (“life line”) A Left palm and wrist. Distal wrist crease Proximal wrist crease Ulnar tunnel (with ulnar a. and n.) Palmar carpal lig. BPalm and wrist showing the carpal and ulnar tunnels. Flexor retinaculum (roof of carpal tunnel) Palmar aponeurosis (cut) Median n. 295 25 Shoulder & Arm Upper Limb Bones of the Upper Limb Fig. 25.1 Bones of the upper limb Right limb. The upper limb is subdivided into three regions: arm, forearm, and hand. The shoulder girdle (clavicle and scapula) joins the upper limb to the thorax at the sternoclavicular joint. Clavicle Clavicle Acromioclavicular joint Shoulder joint Shoulder girdle Scapula Arm Scapula Scapular spine Humerus Humerus Elbow joint Olecranon Head of radius Forearm Radius Radius Ulna Ulna 1st metacarpal Carpals Carpal bones Metacarpals Hand 4th proximal phalanx Phalanges 4th middle phalanx 4th distal phalanx A Anterior view. 296 B Posterior view. Fig. 25.2 Bones of the shoulder girdle in normal relation to those of the trunk Acromion Acromion Clavicle Coracoid process Clavicle Sternoclavicular joint Glenoid cavity Coracoid process Manubrium Scapula, costal surface 25 Shoulder & Arm First rib Body of sternum Scapula Inferior angle Superior angle Humerus Clavicle A Anterior view. Acromion Scapula, posterior surface Medial border Inferior angle Ulna Acromioclavicular joint Radius First rib Clavicle Acromion Coracoid process 1st metacarpal 2nd metacarpal 1st proximal phalanx 1st distal phalanx B Posterior view. Glenoid cavity Scapula, posterior surface Lateral border Phalanges C Lateral view. C Lateral view. 297 Upper Limb Clavicle & Scapula The shoulder girdle (clavicle and scapula) connects the bones of the upper limb to the thoracic cage. Whereas the pelvic girdle (paired hip bones) is firmly integrated into the axial skeleton (see p. 230), the shoulder girdle is extremely mobile. Fig. 25.3 Shoulder girdle in situ Right shoulder, superior view. Suprascapular fossa Acromion Acromioclavicular joint Coracoid process Clavicle Fig. 25.4 Clavicle Right clavicle. The S-shaped clavicle is visible and palpable along its entire length (generally 12 to 15 cm). Its medial end articulates with the sternum at the sternoclavicular joint. Its lateral end articulates with the scapula at the acromio­clavicular joint (see Fig. 25.3). Sternoclavicular joint Manubrium Conoid tubercle Acromial end Sternal articular surface Shaft of clavicle Sternal end Superior view. A Sternal end Acromial articular surface Impression for costoclavicular lig. Acromial end B Inferior view. 298 Groove for subclavius muscle Conoid tubercle Acromion Coracoid process Scapular notch Superior border Fig. 25.5 Scapula Superior angle Right scapula. In its normal anatomical position, the scapula extends from the 2nd to the 7th rib. 25 Shoulder & Arm Subscapular fossa Supraglenoid tubercle Acromion Lateral angle Superior angle Glenoid cavity Coracoid process Infraglenoid tubercle Supraglenoid tubercle Glenoid cavity Neck Medial border Lateral border Infraglenoid tubercle Lateral border Posterior surface A Anterior view. Costal surface Inferior angle Superior angle Superior border Scapular notch Scapular spine Coracoid process Acromion Inferior angle B Right lateral view. Supraspinous fossa Acromial angle Glenoid cavity Infraglenoid tubercle Medial border Infraspinous fossa Lateral border Clinical box 25.1 Scapular foramen The superior transverse ligament of the scapula (see Fig. 25.14) may become ossified, transforming the scapular notch into an anomalous bony canal, the scapular foramen. This can lead to compression of the suprascapular nerve as it passes through the canal (see p. 381). Scapular foramen Inferior angle Posterior view. C 299 Upper Limb Humerus Fig. 25.6 Humerus Right humerus. The head of the humerus articulates with the scapula at the glenohumeral joint (see p. 302). The capitulum and trochlea of the Greater Intertubercular Lesser groove tubercle tubercle Anatomical neck humerus articulate with the radius and ulna, respectively, at the elbow (cubital) joint (see p. 326). Greater tubercle Intertubercular groove Head of humerus Lesser tubercle Anatomical neck Greater tubercle Head of humerus Anatomical neck Surgical neck Surgical neck Crest of lesser tubercle Crest of greater tubercle Radial groove (for radial n.) Deltoid tuberosity Shaft of humerus, posterior surface Anterolateral surface Shaft of humerus, anterolateral surface Anteromedial surface Lateral supracondylar ridge Medial supracondylar ridge Lateral border Lateral supracondylar ridge Medial supracondylar ridge Lateral border Coronoid fossa Radial fossa Medial epicondyle Lateral Capitulum Trochlea epicondyle Condyle of humerus A Anterior view. 300 Medial border Lateral supracondylar ridge Radial fossa Medial epicondyle Capitulum Lateral epicondyle B Lateral view. Ulnar groove (for ulnar n.) Olecranon Trochlea fossa C Posterior view. Lateral epicondyle Fractures of the humerus Anterior view. Fractures of the proximal humerus are very common and occur predominantly in older patients who sustain a fall onto the outstretched arm or directly onto the shoulder. Three main types are distinguished. Anatomical Head of neck humerus Lesser tubercle Crest of lesser tubercle Head of humerus Anatomical neck Greater tubercle Lesser tubercle Intertubercular groove Surgical neck 25 Shoulder & Arm Clinical box 25.2 Greater tubercle A Extra-articular fracture. Intertubercular groove Lesser tubercle Head of humerus E Proximal (superior) view. Anatomical neck Shaft of humerus, anteromedial surface Capitulum Lateral epicondyle Medial border Olecranon fossa Ulnar groove B Intra-articular fracture. Medial epicondyle F Distal (inferior) view. Comminuted fracture. C Medial supracondylar ridge Olecranon fossa Trochlea of humerus Medial epicondyle DMedial view. Capitulotrochlear Trochlea groove Extra-articular fractures and intra-articular fractures are often accompanied by injuries of the blood vessels that supply the humeral head (anterior and posterior circumflex humeral arteries), with an associated risk of post-traumatic avascular necrosis. Fractures of the surgical neck can damage the axillary nerve and fractures of the humeral shaft and distal humerus are frequently associated with damage to the radial nerve. 301 Upper Limb Joints of the Shoulder Fig. 25.7 Joints of the shoulder: Overview Right shoulder, anterior view. Acromioclavicular joint Subacromial space Scapulothoracic joint Sternoclavicular joint Glenohumeral joint Fig. 25.8 Joints of the shoulder girdle Right side, superior view. Acromioclavicular joint (with acromioclavicular lig.) Coracoacromial lig. Fig. 25.9 Scapulothoracic joint Right side, superior view. In all movements of the shoulder girdle, the scapula glides on a curved surface of loose connective tissue between the serratus anterior and the subscapularis muscles. This surface can be considered a scapulothoracic joint. Scapulothoracic joint Subscapularis Acromion Head of humerus Coracoid process Serratus anterior Clavicle 302 Glenohumeral joint Superior posterior serratus Scapulothoracic joint Posterior sternoclavicular lig. Sternoclavicular joint (with anterior sternoclavicular lig.) Fig. 25.10 Sternoclavicular joint Anterior sternoclavicular lig. Clavicle Costal cartilage Fig. 25.11 Acromioclavicular joint Anterior view. The acromioclavicular joint is a plane joint. Because the articulating surfaces are flat, they must be held in place by strong ligaments, greatly limiting the mobility of the joint. Acromioclavicular lig. Interclavicular lig. Articular disk Costoclavicular lig. 1st rib 25 Shoulder & Arm Anterior view with sternum coronally sectioned (left). Note: A fibrocartilaginous articular disk compensates for the mismatch of surfaces between the two saddle-shaped articular facets of the clavicle and the manubrium. Clavicle, acromial end Manubrium Coracoclavicular lig. Trapezoid lig. Conoid lig. Sternocostal joint Clavicle, sternal end Acromion Coracoacromial arch Coracoacromial lig. Superior angle Coracoid process Superior transverse lig. of scapula Head of humerus Scapular notch Greater tubercle Lesser tubercle Intertubercular groove Scapula, costal (anterior) surface Glenoid cavity Medial border Humerus Clinical box 25.3 Injuries of the acromioclavicular joint A fall onto the outstretched arm or shoulder frequently causes dislocation of the acromioclavicular joint (often known as a “shoulder separation”) and damage to the coracoclavicular ligaments. A Stretching of acromio­ clavicular ligaments. B Rupture of acromioclavicular ligament. C Complete dislocation of acromioclavicular joint. Note rupture of acromioclavicular and coracoclavicular ligaments. 303 Upper Limb Joints of the Shoulder: Glenohumeral Joint Fig. 25.12 Glenohumeral joint: Bony elements Right shoulder. Coracoid process Supraglenoid tubercle Clavicle Scapular notch Scapular notch Scapular spine Clavicle Acromion Acromion Head of humerus Lesser tubercle Head of humerus Greater tubercle Greater tubercle Glenoid cavity Intertubercular groove Anatomical neck Infraglenoid tubercle Infraspinous fossa Lateral border of scapula A Anterior view. Humerus B Posterior view. Fig. 25.13 Glenohumeral joint cavity AcromioCoracoclavicular acromial lig. lig. Acromion Acromion Coracoid process Scapular spine Greater tubercle Coracoclavicular lig. Coracoid process Superior transverse lig. of Clavicle scapula Subcoracoid bursa Synovial membrane Lesser tubercle Transverse lig. of humerus Humerus C Lateral view. 304 Axillary recess IntertuberTendon of Subtendinous biceps brachii, Intertubercular cular synovial bursa of groove sheath long head subscapularis Fig. 25.14 Glenohumeral joint: Capsule and ligaments Right shoulder. Superior transverse lig. of scapula Clavicle Coracoacromial lig. Acromion Coracoacromial arch Scapular notch Coracoclavicular lig. Clavicle Acromioclavicular lig. Scapular notch Coracoid process Acromion Coracohumeral lig. Greater tubercle 25 Shoulder & Arm Acromioclavicular Coracoclavicular lig. lig. Intertubercular synovial sheath Intertubercular groove Axillary recess Neck of scapula Lateral border Joint capsule, glenohumeral ligs. A Anterior view. Humerus Axillary recess Scapula, costal surface Infraspinous fossa Scapular spine Joint capsule B Posterior view. Fig. 25.15 Ligaments reinforcing capsule Schematic representation of the ligaments reinforcing the capsule after removal of the humeral head. Right shoulder. Glenoid cavity Acromion Coracoacromial lig. Supraspinatus Tendon of biceps brachii, long head Tendon of biceps brachii, long head Coracohumeral lig. Coracohumeral lig. Superior glenohumeral lig. Superior glenohumeral lig. Subscapularis Middle glenohumeral lig. Middle glenohumeral lig. Posterior band Axillary recess Anterior band Inferior glenohumeral lig. Lateral view. A Anatomic neck of humerus Inferior glenohumeral lig. Triceps brachii, long head Posterior view. B 305 Upper Limb Subacromial Space & Bursae Fig. 25.16 Subacromial space Fig. 25.17 Subacromial bursa and glenoid cavity Right shoulder. Right shoulder, lateral view of sagittal section with humerus removed. Coracoacromial arch Coracoacromial arch Acromion Coracoacromial lig. Acromion Coracoid process Coracoacromial Coracoid lig. process Supraspinatus Subacromial bursa Subtendinous bursa of subscapularis Subdeltoid bursa Subacromial bursa Infraspinatus Subtendinous bursa of subscapularis Greater tubercle Transverse lig. of humerus Intertubercular tendon sheath Infraspinatus Subtendinous bursa of infraspinatus Tendon of biceps brachii, long head Glenoid cavity Subscapularis Glenoid labrum Joint capsule Teres minor Axillary recess Teres minor Biceps brachii, short head Humerus Infraspinatus Subscapularis Biceps brachii, long head Lateral border of scapula A Lateral view. Supraspinatus Scapula Superior transverse lig. of scapula Acromial articular surface Acromion Subacromial bursa Coracoacromial lig. Subdeltoid bursa Coracoid process Coracoacromial arch Greater tubercle 306 Intertubercular groove Joint capsule Lesser tubercle Humerus B Superior view. Note the position of the subacromial bursa between the supraspinatus muscle and the coracoacromial arch. Fig. 25.18 Subacromial and subdeltoid bursae Right shoulder, anterior view. Acromioclavicular lig. 25 Shoulder & Arm Subcutaneous acromial Coracoacromial Coracoacromial bursa arch lig. Trapezius Acromion Coracoclavicular lig. Coracoid process Clavicle Subacromial bursa Superior transverse lig. of scapula Subdeltoid bursa 1st rib Glenohumeral joint capsule Subtendinous bursa of subscapularis Deltoid Tendon sheath in intertubercular groove Subscapularis Humerus A Location of bursae. Biceps brachii, Biceps brachii, Coraco- Teres long head short head brachialis major Skin Subcutaneous tissue Trapezius Acromion Supraspinatus tendon Head of humerus Subdeltoid bursa Subacromial bursa Supraspinatus Glenoid cavity Scapula Subscapularis Glenoid labrum Deltoid Axillary recess Teres major Latissimus dorsi B Coronal section. The arrows are pointing at the supraspinatus tendon, which is frequently injured in a “rotator cuff tear” (for rotator cuff, see p. 317). Humerus 307 Upper Limb Anterior Muscles of the Shoulder & Arm (I) Fig. 25.19 Anterior muscles of the shoulder and arm Right side, anterior view. Muscle origins are shown in red, insertions in blue. 1st rib Clavicle Trapezius Vertebra prominens (C7) Sternocleidomastoid Deltoid Manubrium Clavicular part Coracobrachialis Sternocostal part Teres major Latissimus dorsi Abdominal part Long head Biceps brachii Short head Body of sternum Serratus anterior Rectus sheath Biceps brachii Brachialis Medial epicondyle A Superficial dissection. 308 External oblique Pectoralis major Clavicular part Deltoid 25 Shoulder & Arm Supraspinatus Pectoralis minor Trapezius Subclavius Clavicle Acromial part Sternocleidomastoid Coracoid process Greater tubercle Pectoralis major, clavicular part Subscapularis Sternum, manubrium Pectoralis major Coracobrachialis Costal cartilage Deltoid Teres major Biceps brachii Sternum, body Serratus anterior Long head Pectoralis major, sternocostal part Short head Latissimus dorsi Sternum, xiphoid process T12 vertebral body Lateral epicondyle Costal arch (margin) Brachialis Medial epicondyle B Deep dissection. Removed: Sternocleidomastoid, trapezius, pectoralis major, deltoid, and external oblique muscles. 309 Upper Limb Anterior Muscles of the Shoulder & Arm (II) Fig. 25.20 Anterior muscles of the shoulder and arm: Dissection Right arm, anterior view. Muscle origins are shown in red, insertions in blue. Subclavius Deltoid Trapezius Supraspinatus Supraspinatus Serratus anterior Serratus anterior Pectoralis minor Coracobrachialis Coracobrachialis Pectoralis major Pectoralis major Latissimus dorsi Biceps brachii, short head Biceps brachii, short head Biceps brachii, long head Biceps brachii, long head Teres major Subscapularis Teres major Pronator teres Common head of superficial flexors Brachialis Brachialis Biceps brachii tendon Bicipital aponeurosis A Removed: Thoracic skeleton. Partially removed: Latissimus dorsi and serratus anterior. 310 Biceps brachii tendon Bicipital aponeurosis B Removed: Latissimus dorsi and serratus anterior. Subscapularis Biceps brachii, short head, and coracobrachialis Biceps brachii, short head Supraspinatus Supraspinatus Subscapularis Subscapularis Subclavius Trapezius Serratus anterior 25 Shoulder & Arm Pectoralis minor Deltoid Intertubercular groove Latissimus dorsi Latissimus dorsi Biceps brachii, long head Teres major Pectoralis major Pectoralis major Biceps brachii, long head Deltoid Deltoid Coracobrachialis Teres major Coracobrachialis Subscapularis Subscapularis Brachialis Brachialis Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Common head of extensors Pronator teres Common head of superficial flexors Brachialis Biceps brachii, radial tuberosity Supinator Biceps brachii Flexor digitorum profundus C Removed: Subscapularis and supraspinatus. Partially removed: Biceps brachii. DRemoved: Biceps brachii, coracobrachialis, and teres major. 311 Upper Limb Posterior Muscles of the Shoulder & Arm (I) Fig. 25.21 Posterior muscles of the shoulder and arm Right side, posterior view. Semispinalis capitis Sternocleidomastoid Splenius capitis Descending part Trapezius Transverse part Scapular spine Deltoid Ascending part Teres major Long head Triceps brachii Lateral head Latissimus dorsi Extensor carpi radialis brevis Extensor carpi radialis longus Olecranon Anconeus External oblique Thoracolumbar fascia Flexor carpi ulnaris Extensor carpi ulnaris Extensor digitorum A Superficial dissection. 312 Iliac crest Internal oblique 25 Shoulder & Arm Superior nuchal line Sternocleidomastoid Semispinalis capitis Splenius capitis Splenius cervicis Rhomboid minor Levator scapulae Rhomboid major Clavicle Acromion Supraspinatus Trapezius (cut ) Scapular spine Scapula, medial border Infraspinatus Teres minor Teres major Intrinsic back muscles, thoracolumbar fascia, posterior layer Latissimus dorsi (cut) Serratus anterior Serratus posterior inferior Latissimus dorsi (cut) B Deep dissection. Partially removed: Trapezius and latissimus dorsi. External oblique Thoracolumbar fascia, posterior layer Internal oblique 313 Upper Limb Posterior Muscles of the Shoulder & Arm (II) Fig. 25.22 Posterior muscles of the shoulder and arm: Dissection Right arm, posterior view. Muscle origins are shown in red, insertions in blue. Rhomboid minor Levator scapulae Supraspinatus Supraspinatus Trapezius Deltoid (clavicular part) Deltoid Deltoid (acromial part) Deltoid (spinal part) Teres minor Infraspinatus Infraspinatus Teres minor Teres major Rhomboid major Triceps brachii, medial head Teres major Triceps brachii, lateral head Latissimus dorsi (scapular part) Triceps brachii, long head Triceps brachii, lateral head Triceps brachii, long head Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Olecranon Anconeus Flexor carpi ulnaris Extensor carpi ulnaris Extensor carpi radialis brevis Common head of extensors Common head of superficial flexors Anconeus Flexor carpi ulnaris Flexor digitorum profundus Extensor digitorum A Removed: Rhomboids major and minor, serratus anterior, and levator scapulae. 314 B Removed: Deltoid and forearm muscles. Supinator Rhomboid minor Levator scapulae Supraspinatus Trapezius Deltoid (clavicular part) 25 Shoulder & Arm Supraspinatus Deltoid (acromial part) Supraspinatus Supraspinatus Infraspinatus Infraspinatus Teres minor Teres minor Deltoid (spinal part) Triceps brachii, lateral head Triceps brachii, long head Teres minor Teres minor Infraspinatus Teres major Triceps brachii, long head Infraspinatus Teres major Deltoid Brachialis Triceps brachii, lateral head Rhomboid major Latissimus dorsi (scapular part) Triceps brachii, medial head Radial groove Deltoid Brachialis Triceps brachii, medial head Triceps brachii, lateral head (cut edge) Extensor carpi radialis longus Brachioradialis Extensor carpi radialis brevis Common head of extensors Common head of superficial flexors Triceps brachii Anconeus C Removed: Supraspinatus, infraspinatus, and teres minor. Partially removed: Triceps brachii. DRemoved: Triceps brachii and teres major. 315 Upper Limb Muscle Facts (I) The actions of the three parts of the deltoid muscle depend on their relationship to the position of the humerus and its axis of motion. At less than 60 degrees, the muscles act as adductors, but at greater than 60 degrees, they act as abductors. As a result, the parts of the deltoid can act antagonistically as well as synergistically. Acromion Fig. 25.23 Deltoid Right shoulder. Clavicle Scapular spine DS Deltoid, clavicular part Deltoid, acromial part A Deltoid, spinal part Scapula A Parts of the deltoid, right lateral view, schematic. Acromion B Right lateral view. Deltoid, clavicular part Shaft of Deltoid humerus tuberosity Clavicle Coracoid Deltoid, process clavicular part Deltoid, acromial part Acromion Clavicle Scapula, costal surface Deltoid, acromial part Scapular spine Deltoid, spinal part Scapula, posterior surface Deltoid tuberosity Deltoid tuberosity Shaft of humerus Shaft of humerus C Anterior view. Table 25.1 DPosterior view. Parts of the deltoid Muscle Deltoid Origin ① Clavicular (anterior) part Lateral one third of clavicle ② Acromial (lateral) part Acromion ③ Spinal (posterior) part Scapular spine Insertion Innervation Humerus (deltoid tuberosity) Axillary n. (C5, C6) Flexion, internal rotation, adduction * Between 60 and 90 degrees of abduction, the clavicular and spinal parts assist the acromial part with abduction. 316 Action* Abduction Extension, external rotation, adduction A Fig. 25.24 Rotator cuff Right shoulder. The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. F Acromion Supraspinatus Coracoid process Greater tuberosity A Posterior view, schematic. Acromion Coracoid process Subscapularis Infraspinatus B Anterior view, schematic. 25 Shoulder & Arm S D Teres minor Scapular Supra- Superior notch spinatus border Shaft of humerus Superior angle Scapula, lateral border Greater tubercle Lesser tubercle Intertubercular groove Scapula, inferior angle Medial border Crest of greater tubercle DLateral view. Subscapularis Crest of lesser tubercle Supraspinatus Scapular spine Coracoid process Acromion Superior angle Greater tubercle Shaft of humerus Inferior angle C Anterior view. Medial border Infraspinatus Teres minor Shaft of humerus Lateral border E Posterior view. Table 25.2 Muscle Muscles of the rotator cuff Origin Insertion ① Supraspinatus Supraspinous fossa ② Infraspinatus Infraspinous fossa ③ Teres minor ④ Subscapularis Inferior angle Scapula Lateral border Subscapular fossa Humerus Innervation Action Initiates abduction Humerus (greater tubercle) Suprascapular n. (C4–C6) Axillary n. (C5, C6) External rotation, weak adduction Humerus (lesser tubercle) Upper and lower subscapular nn. (C5, C6) Internal rotation External rotation 317 Upper Limb Muscle Facts (II) Fig. 25.25 Pectoralis major and coracobrachialis Anterior view. Acromion F A Pectoralis major, clavicular part Clavicle Coracoid process S Lesser tubercle D Intertubercular groove Pectoralis major, sternocostal part Crest of greater tubercle Sternum Coracobrachialis A Schematic. Pectoralis major, abdominal part Humerus Clavicular part Sternocostal part Abdominal part C Pectoralis major and coracobrachialis. B Pectoralis major in neutral position (left) and elevation (right). Table 25.3 Pectoralis major and coracobrachialis Muscle Pectoralis major ④ Coracobrachialis 318 Origin ① Clavicular part Clavicle (medial half) ② Sternocostal part Sternum and costal cartilages 1–6 ③ Abdominal part Rectus sheath (anterior layer) Scapula (coracoid process) Insertion Innervation Action Humerus (crest of greater tubercle) Medial and lateral pectoral nn. (C5–T1) Entire muscle: adduction, internal rotation Clavicular and sternocostal parts: flexion; assist in respiration when shoulder is fixed Humerus (in line with crest of lesser tubercle) Musculocutaneous n. (C5–C7) Flexion, adduction, internal rotation Fig. 25.26 Subclavius and pectoralis minor Clavicle Right side, anterior view. 1st rib A 25 Shoulder & Arm S Acromion Coracoid process Subclavius A Schematic. Pectoralis minor Fig. 25.27 Serratus anterior Right lateral view. 3rd through 5th ribs Coracoid process Acromion 1st rib Glenoid cavity Medial border B Subclavius and pectoralis minor. Scapula Serratus anterior Inferior angle D F G 9th rib A Serratus anterior. Table 25.4 B Schematic. Subclavius, pectoralis minor, and serratus anterior Muscle Origin Insertion Innervation Action ① Subclavius 1st rib Clavicle (inferior surface) N. to subclavius (C5, C6) Steadies the clavicle in the sternoclavicular joint ② Pectoralis minor 3rd to 5th ribs Coracoid process Medial pectoral n. (C8, T1) Draws scapula downward, causing inferior angle to move posteromedially; rotates glenoid inferiorly; assists in respiration Scapula (costal and dorsal surfaces of superior angle) ③ Superior part Serratus anterior ④ Intermediate part ⑤ Inferior part 1st to 9th ribs Scapula (costal surface of medial border) Scapula (costal surface of medial border and costal and dorsal surfaces of inferior angle) Superior part: lowers the raised arm Long thoracic n. (C5–C7) Entire muscle: draws scapula laterally forward; elevates ribs when shoulder is fixed Inferior part: rotates inferior angle of scapula laterally forward (allows elevation of arm above 90°) 319 Muscle Facts (III) Upper Limb Fig. 25.28 Trapezius Posterior view. External occipital protuberance Superior nuchal line A Nuchal lig. S Trapezius (descending part) C7 spinous process Trapezius (transverse part) D Acromion Scapular spine B Schematic. Trapezius (ascending part) C1 (atlas) C1–C4 transverse processes C2 (axis) A Trapezius. Levator scapulae Rhomboid minor T12 spinous process Fig. 25.29 Levator scapulae with rhomboids major and minor Superior Clavicle angle C7 spinous process Acromion T1–T4 spinous processes Right side, posterior view. Scapular spine Medial border Rhomboid major F G Scapula, posterior surface Inferior angle H A Schematic. Table 25.5 Trapezius, levator scapulae, and rhomboids major and minor Muscle Origin Insertion ① Descending part Occipital bone; spinous processes of C1–C7 Clavicle (lateral one third) ②T ransverse part Aponeurosis at T1–T4 spinous processes Acromion ③ Ascending part Spinous processes of T5–T12 Scapular spine ④ Levator scapulae Transverse processes of C1–C4 Scapula (superior angle) Dorsal scapular n. and cervical spinal nn. (C3–C4) Draws scapula medially upward while moving inferior angle medially; inclines neck to same side ⑤ Rhomboid minor Spinous processes of C6, C7 Spinous processes of T1–T4 vertebrae Dorsal scapular n. (C4–C5) Steadies scapula; draws scapula medially upward ⑥ Rhomboid major Medial border of scapula above (minor) and below (major) scapular spine Trapezius CN, cranial nerve. 320 B Levator scapulae with rhomboids major and minor. Innervation Action Draws scapula obliquely upward; rotates glenoid cavity superiorly; tilts head to same side and rotates it to opposite Accessory n. (CN XI); C3–C4 of cervical plexus Draws scapula medially Draws scapula medially downward Entire muscle: steadies scapula on thorax Fig. 25.30 Latissimus dorsi and teres major Posterior view. Latissimus dorsi (scapular part) Humerus T7 spinous processes 25 Shoulder & Arm Scapula Teres major Latissimus dorsi (vertebral part) S A D Latissimus dorsi (iliac part) Thoracolumbar fascia F Iliac crest Ilium Sacrum A Latissimus dorsi, schematic. B Latissimus dorsi and teres major. Acromion Coracoid process Clavicle Intertubercular groove DInsertion of the latisCrest of lesser simus dorsi on the tubercle floor of the intertubercular groove Teres major and the teres major on the crest of the Latissimus lesser tubercle of the dorsi humerus. G C Teres major, schematic. Table 25.6 Origin ①V ertebral part Spinous processes of T7–T12 vertebrae; thoracolumbar fascia ② Scapular part Scapula (inferior angle) ③ Costal part 9th to 12th ribs ④ Iliac part Iliac crest (posterior one third) ⑤ Teres major Inferior angle Latissimus dorsi and teres major Muscle Latissimus dorsi Scapula, costal surface Scapula (inferior angle) Insertion Innervation Action Floor of the intertubercular groove of the humerus Thoracodorsal n. (C6–C8) Internal rotation, adduction, extension, respiration (“cough muscle”) Crest of lesser tubercle of the humerus (anterior angle) Lower subscapular n. (C5, C6) Internal rotation, adduction, extension 321 Upper Limb Muscle Facts (IV) The anterior and posterior muscles of the arm may be classified respectively as flexors and extensors relative to the movement of the elbow joint. Although the coracobrachialis is topographically part of the anterior compartment, it is functionally grouped with the muscles of the shoulder (see p. 318). Fig. 25.31 Biceps brachii and brachialis Scapula, anterior surface Supraglenoid tubercle Coracoid process Right arm, anterior view. Greater tubercle Lesser tubercle A S Intertubercular groove D Biceps brachii, long head Shaft of humerus Biceps brachii, short head A Schematic. Brachialis Biceps brachii Medial epicondyle Brachialis Lateral epicondyle Bicipital aponeurosis Radial tuberosity, biceps brachii tendon B Biceps brachii and brachialis. Table 25.7 C Brachialis. Origin Insertion ① Long head Supraglenoid tubercle of scapula ②S hort head Coracoid process of scapula ③ Brachialis Ulnar tuberosity Anterior muscles: Biceps brachii and brachialis Muscle Biceps brachii Radial tuberosity Ulnar tuberosity, brachialis tendon Humerus (distal half of anterior surface) Innervation Action Radial tuberosity and bicipital aponeurosis Musculocutaneous n. (C5–C6) Elbow joint: flexion; supination* Shoulder joint: flexion; stabilization of humeral head during deltoid contraction; abduction and internal rotation of the humerus Ulnar tuberosity Musculocutaneous n. (C5–C6) and radial n. (C7, minor) Flexion at the elbow joint * Note: When the elbow is flexed, the biceps brachii acts as a powerful supinator because the lever arm is almost perpendicular to the axis of pronation/supination. 322 Fig. 25.32 Triceps brachii and anconeus Right arm, posterior view. Scapular spine Lateral head tendon of origin Acromion Long head A Radial groove Greater tubercle Infraglenoid tubercle D 25 Shoulder & Arm Scapula, posterior surface S Medial head F Tendon of insertion Shaft of humerus Triceps brachii, medial head Lateral border Triceps brachii, long head Triceps brachii, lateral head DSchematic. Anconeus B Partially removed: Lateral head of triceps brachii. Shaft of humerus Long head tendon of origin Lateral head Medial head Medial epicondyle Lateral epicondyle Olecranon Anconeus Tendon of insertion Anconeus Ulna Radius A Triceps brachii and anconeus. Table 25.8 Posterior muscles: Triceps brachii and anconeus Muscle Triceps brachii Origin ① Long head Scapula (infraglenoid tubercle) ② Medial head Posterior humerus, distal to radial groove; medial intermuscular septum ③ Lateral head Posterior humerus, proximal to radial groove; lateral intermuscular septum ④ Anconeus C Partially removed: Long head of triceps brachii. Lateral epicondyle of humerus (variance: posterior joint capsule) Insertion Olecranon of ulna Olecranon of ulna (radial surface) Innervation Radial n. (C6–C8) Action Elbow joint: extension Shoulder joint, long head: extension and adduction Extends the elbow and tightens its joint 323 26 Elbow & Forearm Upper Limb Radius & Ulna Fig. 26.1 Radius and ulna Right forearm. Olecranon Trochlear notch Articular fovea Head of radius, articular circumference Head of radius, articular circumference Coronoid process Neck of radius Radial notch Radial notch Radial tuberosity Coronoid process Ulnar tuberosity Anterior border Shaft of ulna, anterior surface Neck of radius Radial tuberosity Posterior border Medial surface Interosseous border Interosseous border Posterior border Shaft of radius, anterior surface Posterior surface Lateral surface Articular circumference Styloid process of radius A Anterior view. 324 Carpal articular surface Head of ulna Styloid process of ulna Dorsal tubercle Head of ulna Styloid process of ulna B Posterior view. Styloid process of radius Posterior Proximal radioulnar joint Olecranon Trochlear notch Trochlear notch Proximal radioulnar joint Cartilage-free strip Articular fovea Coronoid process Head of radius Head of radius, Articular articular fovea circumference Radial notch 26 Elbow & Forearm Olecranon Coronoid process DProximal (superior) view. Ulnar tuberosity Radial tuberosity Posterior Posterior Radial Ulnar Posterior surface interosseous interosseous surface border border Shaft of ulna, anterior surface Anterior border Radius Lateral surface Anterior border Anterior surface Ulna Interosseous membrane Anterior surface Medial surface E Transverse section, proximal view. Shaft of radius, anterior surface Interosseous border Interosseous membrane Carpal articular surface Distal radioulnar joint Anterior Head of ulna Head of ulna Styloid process of radius C Anterosuperior view. Distal radioulnar joint Styloid process of radius Dorsal tubercle Ulnar notch of radius Styloid process of ulna F Distal (inferior) view. 325 Upper Limb Elbow Joint Fig. 26.2 Elbow (cubital) joint Right limb. The elbow consists of three articulations between the humerus, ulna, and radius: the humeroulnar, humeroradial, and proximal radioulnar joints. Humerus Humerus Lateral border Medial supracondylar ridge Lateral supracondylar ridge Coronoid fossa Radial fossa Lateral epicondyle Medial epicondyle Capitulum Trochlea Coronoid process Head of radius Neck of radius Capitulotrochlear groove Medial supracondylar ridge Lateral supracondylar ridge Olecranon fossa Lateral epicondyle Medial epicondyle Ulnar groove Head of radius, articular circumference Olecranon Ulnar tuberosity Radial tuberosity Radius Radius Ulna Ulna B Posterior view. A Anterior view. Humerus Humerus Radial tuberosity Radius Head of radius Medial supracondylar ridge Capitulum Medial epicondyle Olecranon Ulna C Medial view. 326 Coronoid process Lateral supracondylar ridge Humeroradial joint Radius Lateral epicondyle Capitulum Humeroulnar joint Olecranon Trochlea DLateral view. Proximal radioulnar joint Head of radius Ulna Clinical box 26.1 Humerus Brachioradialis Triceps brachii Medial epicondyle Lateral epicondyle Capitulotrochlear groove Extensor carpi radialis longus Ulnar collateral lig. Radial collateral lig. Humeroulnar joint (humeral trochlea and trochlear notch) Proximal radioulnar joint (articular circumference and radial notch of ulna) Forearm flexors Ulna Supinator Humeroradial joint (capitulum of humerus and articular fovea) Anular lig. of radius Head of radius Sacciform recess Biceps brachii tendon Plane of Plane of section in b section in c A C oronal section viewed from the front (note the planes of section shown in B and C). Brachialis Humerus Triceps brachii The fat pads between the fibrous capsule and synovial membrane are part of the normal anatomy of the elbow joint. The anterior pad is most readily seen on a sagittal MRI while the posterior pad is often hidden within the bony fossa (see Figs. 26.3 and 29.11). With an effusion of the joint space, the inferior edge of the anterior pad appears concave as it gets pushed superiorly by the intra-articular fluid. This causes the pad to resemble the shape of a ship’s sail, thus creating a characteristic “sail sign.” The alignment of the prominences in the elbow also aids in the identification of fractures and dislocations. 26 Elbow & Forearm Assessing elbow injuries Fig. 26.3 Skeletal and soft-tissue elements of the right elbow joint A Posterior view of extended elbow: The ­epicondyles and olecranon lie in a straight line. B Medial view of flexed e ­ lbow: The epicondyles and olecranon lie in a straight line. C Posterior view of flexed elbow: The two epicondyles and the tip of the olecranon form an equilateral triangle. Fractures and dislocations alter the shape of the triangle. Brachialis Humerus Triceps brachii Fat pad Capitulum Coronoid fossa Olecranon fossa Olecranon bursa Trochlea Fat pad Brachioradialis Articular circumference Articular fovea Head of radius Radial notch of ulna Olecranon Trochlear notch Anconeus Supinator Radius Ulna B Sagittal section through the humeroradial joint and proximal radioulnar joint, medial view. Coronoid process Ulna CSagittal section through the humeroulnar joint, ­medial view. 327 Ligaments of the Elbow Joint Upper Limb Fig. 26.4 Ligaments of the elbow joint Right elbow in flexion. Humerus Lateral supracondylar ridge Olecranon fossa Lateral epicondyle Medial epicondyle Radial collateral lig. Ulnar groove Ulnar collateral lig. Humerus Olecranon Radial tuberosity Radius A Posterior view. Anular lig. of radius Ulnar collateral lig. (anterior part) Medial epicondyle Ulnar collateral lig. (posterior part) Humerus Ulnar collateral lig. (transverse part) Lesser tubercle, supracondylar ridge Ulna Sacciform recess Radius Table 26.1 C Lateral view. 328 Radial collateral lig. Olecranon B Medial view. Lateral epicondyle Olecranon Coronoid process Anular lig. of radius Neck of radius Ulna Joints and ligaments of the elbow Joint Articulating surfaces Ligament Humeroulnar joint Trochlea Ulna (trochlear notch) Ulnar collateral ligament Humeroradial joint Capitulum Radius (articular fovea) Radial collateral ligament Proximal radioulnar joint Radius (articular circumference) Ulna (radial notch) Anular ligament Fig. 26.5 Joint capsule of the elbow Right elbow in extension, anterior view. 26 Elbow & Forearm Humerus Medial epicondyle Joint capsule Lateral epicondyle Radial collateral lig. Ulnar collateral lig. Anular lig. of radius Radial tuberosity Radius Ulnar tuberosity Ulna A Intact joint capsule. Clinical box 26.2 Humerus Subluxation of the radial head (nursemaid’s elbow) A common and painful injury of small children occurs when the arm is jerked upward with the forearm pronated, tearing the anular ligament from its loose attachment on the radial neck. As the immature radial head slips out of the socket, the ligament may become trapped between the radial head and the capitulum of the humerus. Supinating the forearm and flexing the elbow usually returns the radial head to the normal position. Radial fossa Coronoid fossa Capitulotrochlear groove Medial epicondyle Lateral epicondyle Capitulum Trochlea Radial collateral lig. Ulnar collateral lig. Head of radius Humerus Anular lig. of radius Coronoid process Sacciform recess Capitulum Radial head Ulna Epiphyseal plates Radius Ulna Anular lig. B Windowed joint capsule. 329 Upper Limb Radioulnar Joints The proximal and distal radioulnar joints function together to enable pronation and supination movements of the hand. The joints are functionally linked by the interosseous membrane. The axis for pronation and supination runs obliquely from the center of the humeral capitulum through the center of the radial articular fovea down to the styloid process of the ulna. Fig. 26.6 Supination Fig. 26.7 Pronation Right forearm, anterior view. Right forearm, anterior view. Axis of pronation/ supination Axis of pronation/ supination Radial collateral lig. Radial collateral lig. Olecranon Trochlear notch Coronoid process Articular fovea Ulnar collateral lig. Anular lig. Ulnar tuberosity Radial tuberosity Anular lig. Proximal radioulnar joint Neck of radius Ulnar tuberosity Radial tuberosity Oblique cord Anterior border Shaft of ulna Interosseous border of ulna Interosseous border of ulna Interosseous border of radius Interosseous border Interosseous membrane Interosseous membrane Lateral surface Posterior border Posterior surface Styloid process of radius 330 Head of ulna Dorsal radioulnar lig. Palmar radioulnar lig. Head of ulna Styloid process of ulna Styloid process of ulna Dorsal tubercle Distal radioulnar joint Radius Fig. 26.9 Distal radioulnar joint rotation Right elbow, proximal (superior) view. Right forearm, distal view of articular surfaces of radius and ulna. The dorsal and palmar radioulnar ligaments stabilize the distal radioulnar joint. Olecranon Head of radius, Articular lunula fovea Radius, carpal articular surface Distal radioulnar joint Trochlear notch Palmar radioulnar lig. 26 Elbow & Forearm Fig. 26.8 Proximal radioulnar joint Head of ulna Anular lig. Proximal radioulnar Coronoid joint process Dorsal radioulnar lig. Styloid process of radius A Proximal articular surfaces of radius and ulna. Dorsal tubercle Extensor carpi ulnaris tendon Styloid process of ulna A Supination. Styloid process of radius Olecranon Trochlear notch Ulnar notch Anular lig. Radial notch of ulna Articular circumference Coronoid process B Radius removed. Styloid process of ulna B Semipronation. Clinical box 26.3 Radius fracture Dorsal radioulnar lig. Falls onto the outstretched arm often result in fractures of the distal radius. In a Colles’ fracture, the distal fragment is tilted dorsally. Head of ulna Dorsal A B Styloid process of radius Styloid process of ulna Palmar radioulnar lig. C Pronation. 331 Upper Limb Muscles of the Forearm: Anterior Compartment Fig. 26.10 Anterior muscles of the forearm: Dissection Right forearm, anterior view. Muscle origins are shown in red, insertions in blue. Biceps brachii Triceps brachii Brachialis Brachialis Medial epicondyle, common head of flexors Biceps brachii tendon Medial epicondyle, common head of flexors Bicipital aponeurosis Brachioradialis Biceps brachii Extensor carpi radialis longus Pronator teres Extensor carpi radialis brevis Flexor carpi radialis Pronator teres Supinator Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Flexor digitorum superficialis Flexor pollicis longus Flexor pollicis longus Abductor pollicis longus Pronator quadratus Brachioradialis Palmaris longus Abductor pollicis longus Flexor digitorum superficialis tendons Flexor digitorum superficialis tendons Flexor pollicis longus tendon Flexor pollicis longus tendon Flexor digitorum profundus tendons A Superficial flexors and radialis muscles. 332 Flexor carpi ulnaris Flexor digitorum profundus tendons B Removed: Radialis muscles (brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis), flexor carpi radialis, flexor carpi ulnaris, abductor pollicis longus, palmaris longus, and biceps brachii. Pronator teres, humeral head Medial epicondyle, common head of flexors Biceps brachii Flexor digitorum superficialis, ulnar head Brachioradialis Brachialis Extensor carpi radialis longus Pronator teres, humeral head Extensor carpi radialis brevis Medial epicondyle, common head of flexors Lateral epicondyle, common head of extensors, supinator Biceps brachii Supinator Supinator Flexor digitorum superficialis, radial head Flexor digitorum superficialis, radial head Pronator teres Flexor digitorum profundus Pronator teres 26 Elbow & Forearm Brachialis Flexor digitorum superficialis, ulnar head Pronator teres, ulnar head Brachialis Flexor digitorum profundus Flexor pollicis longus Flexor pollicis longus Pronator quadratus Pronator quadratus Brachioradialis Abductor pollicis longus Flexor pollicis longus Flexor pollicis longus tendon Flexor digitorum profundus tendons C Removed: Pronator teres and flexor digitorum superficialis. Flexor carpi ulnaris Flexor carpi radialis Flexor digitorum superficialis Flexor digitorum profundus DRemoved: Brachialis, supinator, pronator quadratus, and deep flexors. 333 Upper Limb Muscles of the Forearm: Posterior Compartment Fig. 26.11 Posterior muscles of the forearm: Dissection Right forearm, posterior view. Muscle origins are shown in red, insertions in blue. Brachioradialis Brachioradialis Triceps brachii Triceps brachii Medial epicondyle, common head of flexors Olecranon Extensor carpi radialis brevis Anconeus Extensor carpi radialis longus Anconeus Extensor carpi radialis brevis Extensor digitorum Flexor digitorum profundus Supinator Flexor carpi ulnaris Extensor carpi ulnaris Flexor carpi ulnaris Abductor pollicis longus Extensor carpi radialis brevis Extensor digiti minimi Extensor pollicis longus Abductor pollicis longus Brachioradialis Brachioradialis Extensor pollicis brevis Extensor carpi radialis longus Extensor pollicis brevis Extensor carpi ulnaris Extensor indicis Dorsal (“Lister’s”) tubercle of radius Intertendinous connections Extensor digitorum tendons, dorsal digital expansion A Superficial extensors and radialis group. 334 Extensor pollicis longus tendon Extensor carpi radialis brevis tendon Extensor digiti minimi Extensor carpi radialis longus tendon Extensor digitorum B Removed: Triceps brachii, anconeus, flexor carpi ulnaris, extensor carpi ulnaris, and extensor digitorum. Brachioradialis Extensor carpi radialis longus Extensor carpi radialis longus Extensor carpi radialis brevis Lateral epicondyle, common head of extensors Triceps brachii Medial epicondyle, common head of flexors Anconeus Flexor digitorum profundus Supinator Flexor digitorum profundus Extensor carpi radialis brevis 26 Elbow & Forearm Brachioradialis Supinator, humeral head Lateral epicondyle, common head of extensors Supinator Flexor carpi ulnaris Pronator teres Pronator teres Abductor pollicis longus Abductor pollicis longus Extensor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor pollicis brevis Extensor indicis Extensor indicis Extensor carpi ulnaris Brachioradialis Interosseous membrane Brachioradialis Dorsal (“Lister’s”) tubercle Abductor pollicis longus Abductor pollicis longus Extensor carpi radialis brevis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi radialis longus Extensor pollicis brevis Extensor pollicis longus Extensor pollicis longus Extensor digiti minimi Extensor digitorum Extensor indicis C Removed: Abductor pollicis longus, extensor pollicis longus, and radialis muscles. DRemoved: Flexor digitorum profundus, supinator, extensor pollicis brevis, and extensor indicis. 335 Upper Limb Muscle Facts (I) Fig. 26.12 Anterior compartment of the forearm Right forearm, anterior view. Humeral-ulnar head ① Radial head ② ③ ④ ⑥ ⑤ ⑦ ⑧ A Superficial. Table 26.2 B Intermediate. C Deep. Anterior compartment of the forearm Muscle Origin Insertion Humeral head: medial epicondyle of humerus Ulnar head: coronoid process Lateral radius (distal to supinator insertion) Innervation Action Superficial muscles ① Pronator teres ② Flexor carpi radialis Medial epicondyle of humerus Median n. (C6, C7) Wrist: flexion and abduction (radial deviation) of hand Palmar aponeurosis Median n. (C7, C8) Elbow: weak flexion Wrist: flexion tightens palmar aponeurosis Humeral head: medial epicondyle Ulnar head: olecranon Pisiform; hook of hamate; base of 5th metacarpal Ulnar n. (C7–T1) Wrist: flexion and adduction (ulnar deviation) of hand Humeral-ulnar head: medial epicondyle of humerus and coronoid process of ulna Radial head: upper half of anterior border of radius Sides of middle phalanges of 2nd to 5th digits Median n. (C8, T1) Elbow: weak flexion Wrist, MCP, and PIP joints of 2nd to 5th digits: flexion Ulna (proximal two thirds of flexor surface) and interosseous membrane Distal phalanges of 2nd to 5th digits (palmar surface) Median n. (C8, T1, radial half of fingers 2 and 3) Ulnar n. (C8, T1, ulnar half of fingers 4 and 5) Wrist, MCP, PIP, and DIP joints of 2nd to 5th digits: flexion ③ Palmaris longus ④ Flexor carpi ulnaris Base of 2nd metacarpal (variance: base of 3rd metacarpal) Elbow: weak flexion Forearm: pronation Intermediate muscles ⑤ Flexor digitorum superficialis Deep muscles ⑥ Flexor digitorum profundus ⑦ Flexor pollicis longus ⑧ Pronator quadratus Radius (midanterior surface) and adjacent interosseous membrane Distal phalanx of thumb (palmar surface) Distal quarter of ulna (anterior surface) Distal quarter of radius (anterior surface) Median n. (C8, T1) DIP, distal interphalangeal; IP, interphalangeal; MCP, metacarpophalangeal; PIP, proximal interphalangeal. 336 Wrist: flexion and abduction (radial deviation) of hand Carpometacarpal joint of thumb: flexion MCP and IP joints of thumb: flexion Hand: pronation Distal radioulnar joint: stabilization Right forearm, anterior view. Medial epicondyle Medial epicondyle, common head of flexors Radial tuberosity Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Coronoid process Interosseous membrane Flexor digitorum superficialis, radial head Radial tuberosity Flexor digitorum superficialis, humeral-ulnar head 26 Elbow & Forearm Fig. 26.13 Anterior compartment of the forearm Ulnar tuberosity Interosseous membrane Radius Flexor digitorum profundus Flexor pollicis longus Flexor digitorum superficialis Base of 2nd metacarpal Pronator quadratus Tubercle of trapezium Trapezium Pisiform bone Hook of hamate Base of 5th metacarpal Palmar aponeurosis 2nd through 5th middle phalanges A Superficial muscles. Pisiform bone Hook of hamate Base of 1st distal phalanx 4th distal phalanx B Intermediate muscles. C Deep muscles. 337 Upper Limb Muscle Facts (II) Fig. 26.14 Posterior compartment of the forearm: Radialis muscles Right forearm, posterior view, schematic. Clinical box 26.4 Lateral epicondylitis Lateral epicondylitis, or tennis elbow, involves the extensor muscles and tendons of the forearm that attach on the lateral epicondyle. The tendon most commonly involved is that of the extensor carpi radialis brevis, a muscle that helps stabilize the wrist when the elbow is extended. When the extensor carpi radialis brevis is weakened from overuse, microscopic tears form in the tendon where it attaches to the lateral epicondyle. This leads to inflammation and pain. There is some evidence that the inflammation can extend back along the tendon to the periosteum of the lateral epicondyle. A S D Athletes are not the only people who get tennis elbow and are actually in the minority — leading some to suggest the condition be referred to as “lateral elbow syndrome”. Workers whose activities require repetitive and vigorous use of the forearm muscles, such as common to painters, plumbers, and carpenters, are particularly prone to developing this pathology. Studies show a high incidence also among auto workers, cooks, and butchers. Common signs and symptoms of tennis elbow include pain with wrist extension against resistance, point tenderness or burning on the lateral epicondyle, and weak grip strength. Symptoms are intensified with forearm activity. Table 26.3 338 Posterior compartment of the forearm: Radialis muscles Muscle Origin Insertion Innervation Action ① Brachioradialis Distal humerus (lateral surface), lateral intermuscular septum Styloid process of the radius Radial n. (C5, C6) Elbow: flexion Forearm: semipronation ② Extensor carpi radialis longus Lateral supracondylar ridge of distal humerus, lateral intermuscular septum 2nd metacarpal (base) Radial n. (C6, C7) ③ Extensor carpi radialis brevis Lateral epicondyle of humerus 3rd metacarpal (base) Radial n. (C7, C8) Elbow: weak flexion Wrist: extension and abduction Fig. 26.15 Posterior compartment of the forearm: Radialis muscles Right forearm. Brachioradialis Humerus Lateral supracondylar crest Lateral epicondyle Medial epicondyle Lateral epicondyle 26 Elbow & Forearm Humerus Olecranon Olecranon Extensor carpi radialis longus Brachioradialis Ulna Extensor carpi radialis brevis Extensor carpi radialis longus Ulna Extensor carpi radialis brevis Radius Interosseous membrane Radius Brachioradialis tendon Styloid process of radius Styloid process of radius Base of 3rd metacarpal 3rd metacarpal A Lateral (radial) view. Base of 3rd metacarpal Base of 2nd metacarpal Base of 2nd metacarpal 2nd metacarpal Shaft of 2nd metacarpal B Posterior view. 339 Upper Limb Muscle Facts (III) Fig. 26.16 Posterior compartment of the forearm Right forearm, posterior view. ④ ⑤ ③ ② ① ⑥ ⑦ ⑧ A Superficial muscles. Table 26.4 B Deep muscles. Posterior compartment of the forearm Muscle Origin Insertion Innervation Action Superficial muscles ① Extensor digitorum Common head (lateral epicondyle of humerus) ② Extensor digiti minimi Wrist: extension MCP, PIP, and DIP joints of 2nd to 5th digits: extension/abduction of fingers Dorsal digital expansion of 2nd to 5th digits Dorsal digital expansion of 5th digit Radial n. (C7, C8) Wrist: extension, ulnar abduction of hand MCP, PIP, and DIP joints of 5th digit: extension and abduction of 5th digit Common head (lateral epicondyle of humerus) Ulnar head (dorsal surface) Base of 5th metacarpal ④ Supinator Olecranon, lateral epicondyle of humerus, radial collateral ligament, annular ligament of radius Radius (between radial tuberosity and insertion of pronator teres) ⑤ Abductor pollicis longus Radius and ulna (dorsal surfaces, interosseous membrane) Base of 1st metacarpal Radiocarpal joint: abduction of the hand Carpometacarpal joint of thumb: abduction ⑥ Extensor pollicis brevis Radius (posterior surface) and interosseous membrane Base of proximal phalanx of thumb Radiocarpal joint: abduction (radial deviation) of hand Carpometacarpal and MCP joints of thumb: extension ③ Extensor carpi ulnaris Wrist: extension, adduction (ulnar deviation) of hand Deep muscles Radial n. (C6, C7) Radial n. (C7, C8) ⑦ Extensor pollicis longus Ulna (posterior surface) and interosseous membrane Base of distal phalanx of thumb Wrist: extension and abduction (radial deviation) of hand Carpometacarpal joint of thumb: adduction MCP and IP joints of thumb: extension ⑧ Extensor indicis Ulna (posterior surface) and interosseous membrane Posterior digital extension of 2nd digit Wrist: extension MCP, PIP, and DIP joints of 2nd digit: extension DIP, distal interphalangeal; IP, interphalangeal; MCP, metacarpophalangeal; PIP, proximal interphalangeal. 340 Radioulnar joints: supination Fig. 26.17 Posterior compartment of the forearm: Superficial and deep muscles Right forearm, posterior view. Olecranon Common head of extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris Medial epicondyle Lateral epicondyle Ulnar groove Olecranon 26 Elbow & Forearm Lateral epicondyle Supinator Ulna Ulna Extensor carpi ulnaris Posterior border of ulna Extensor digitorum Radius Abductor pollicis longus Extensor digiti minimi Extensor pollicis longus Extensor pollicis brevis Radius Extensor indicis Dorsal tubercle Base of 1st metacarpal Base of 5th metacarpal 5th proximal phalanx, base Dorsal digital expansion, intertendinous connections A Superficial extensors. 2nd metacarpal 1st metacarpal 1st proximal phalanx, base 1st distal phalanx, base B Deep extensors with supinator. 341 27 Wrist & Hand Bones of the Wrist & Hand Upper Limb Fig. 27.1 Dorsal view Right hand. Phalanges 2nd distal phalanx 2nd middle phalanx Metacarpals 2nd proximal phalanx Carpal bones Table 27.1 Bones of the wrist and hand 1st to 5th proximal phalanges Phalanges 2nd to 5th middle phalanges* 1st to 5th distal phalanges Metacarpal bones Carpal bones 1st to 5th metacarpals Trapezium Scaphoid Trapezoid Lunate Capitate Triquetrum Hamate Pisiform *There are only four middle phalanges (the thumb has only a proximal and a distal phalanx). 1st metacarpal Capitate Trapezoid Hamate Triquetrum Trapezium Scaphoid Lunate Styloid process of radius Radius 342 Styloid process of ulna Ulna Fig. 27.3 Radiograph of the wrist 27 Wrist & Hand Anteroposterior view of left limb. Fig. 27.2 Palmar view Right hand. Tuberosity of distal phalanx Trapezoid Head Shaft Hook of hamate Trapezium Middle phalanx Capitate Pisiform Scaphoid Triquetrum Base Lunate Clinical box 27.1 Scaphoid Fractures Head Sesamoid bones Metacarpal Shaft Scaphoid fractures are the most common carpal bone fractures, generally occurring at the narrowed waist between the proximal and distal poles (A, right scaphoid red line; B, white arrow). Because blood supply to the scaphoid is transmitted via the distal segment, fractures at the waist can compromise the supply to the proximal segment, often resulting in nonunion and avascular necrosis. Base Tubercle of trapezium Pisiform Triquetrum Capitate Lunate Ulna Distal Trapezoid Hook of hamate Tubercle of scaphoid Styloid process Styloid process of radius Head A Proximal Radius B 343 Upper Limb Carpal Bones Fig. 27.4 Carpal bones of the right wrist 1st to 5th metacarpals Capitate Hamate Triquetrum Scaphoid Lunate Styloid process of ulna Trapezoid Trapezium Styloid process of radius Dorsal tubercle Radius Ulna A Carpal bones of the right wrist with the wrist in flexion, proximal view. Tubercle of trapezium B Carpal and metacarpal bones of the right wrist with radius and ulna removed, proximal view. 344 Carpal tunnel Pisiform 27 Wrist & Hand Scaphoid Lunate Triquetrum Pisiform Tubercle of scaphoid Articular disk (ulnocarpal disk) Styloid process of radius C Articular surfaces of the radiocarpal joint of the right wrist. The proximal row of carpal bones is shown from the proximal view. The articular surfaces of the radius and ulna, and the articular disk (ulnocarpal disk) are shown from the distal view. Styloid process of ulna Dorsal tubercle Radius, carpal articular surface Articular capsule Ulnar collateral ligament of wrist joint 1st to 5th metacarpals Capitate Hamate Distal row of carpal bones Trapezoid Hook of hamate Trapezium Pisiform Tubercle of trapezium Proximal row of carpal bones Tubercle of scaphoid DArticular surfaces of the midcarpal joint of the right wrist. The distal row of carpal bones is shown from the proximal view. The proximal row is shown from the distal view. Scaphoid Lunate Triquetrum 345 Upper Limb Joints of the Wrist & Hand Fig. 27.5 Joints of the wrist and hand Clinical box 27.2 Abduction and adduction at the metacarpophalangeal joint Distal interphalangeal joint Proximal interphalangeal joint Interphalangeal joint of thumb Abduction and adduction movements are described in relation to the middle finger: all movements away from the middle finger are classified as abduction, all movements toward the middle finger as adduction. Adduction Abduction Metacarpophalangeal joint Metacarpophalangeal joint of thumb Carpometacarpal joints Midcarpal joint Carpometacarpal joint of thumb Radiocarpal joint Distal phalanx Distal radioulnar joint Middle phalanx Distal interphalangeal joint Proximal interphalangeal joint Proximal phalanx A Right hand, posterior (dorsal) view. Metacarpophalangeal joint Collateral ligaments Interphalangeal joint 1st dorsal interosseous Metacarpophalangeal joint 4th dorsal interosseous 5th metacarpal Abductor digiti minimi 1st metacarpal Opponens pollicis Trapezoid Carpometacarpal joint of the thumb Trapezium Radial collateral lig. of wrist joint Scaphoid Midcarpal joint Radiocarpal joint B Coronal section. Right hand, posterior (dorsal) view. 346 Carpometacarpal joint Hamate Capitate Pisiform Triquetrum Ulnar collateral lig. of wrist joint Articular disk (ulnocarpal) Lunate Distal radioulnar joint Interosseous membrane Fig. 27.6 Carpometacarpal joint of the thumb Fig. 27.7 Movements of the carpometacarpal joint of the thumb Right hand, radial view. The 1st metacarpal bone has been moved slightly distally to expose the articular surface of the trapezium. Two cardinal axes of motion are shown here: (a) abduction/adduction and (b) flexion/ extension. Distal phalanx Head Shaft Trapezium Middle phalanx Base 27 Wrist & Hand Abduction/ adduction axis Tuberosity of distal phalanx Phalanx Right hand, Palmar view. Flexion/ extension axis A The neutral (0°) position. B Axes of motion in the carpometacarpal joint of the thumb. Proximal phalanx 1st distal phalanx 1st proximal phalanx Head Shaft 1st metacarpal Metacarpal C Adduction. D Abduction. E Flexion. F Extension. Base a Trapezium Trapezoid Capitate b Styloid process of radius Lunate Scaphoid Styloid process of ulna Radius Ulna G Opposition. 347 Upper Limb Ligaments of the Hand Fig. 27.8 Ligaments of the hand Right hand. Distal interphalangeal joint (collateral ligs.) Proximal interphalangeal joint (collateral ligs.) Metacarpophalangeal joint (collateral ligs.) Dorsal metacarpal ligs. Dorsal carpometacarpal ligs. Dorsal intercarpal ligs. Ulnar collateral lig. of wrist joint Radial collateral lig. of wrist joint Dorsal radiocarpal lig. Dorsal radioulnar lig. A Posterior (dorsal) view. Clinical box 27.3 40–60° Movements at the radiocarpal and midcarpal joints Radial deviation Ulnar deviation 0° 30–40° 20° Transverse axis Palmar flexion and dorsal extension occur around a transverse axis (A) that runs through the lunate bone (radiocarpal joint) and capitate bone (midcarpal joint). Radial and ulnar deviation (B) occur around a dorsopalmar axis that runs through the capitate bone. 0° A 348 Dorsal extension 60–80° Palmar flexion B Dorsopalmar axis 27 Wrist & Hand Distal interphalangeal joint capsule Palmar ligs. Proximal interphalangeal joint capsule Deep transverse metacarpal ligs. Metacarpophalangeal joint capsule Palmar metacarpal ligs. Palmar carpometacarpal ligs. Palmar intercarpal ligs. Flexor carpi ulnaris tendon Radial collateral lig. of wrist joint Palmar ulnocarpal lig. Palmar radiocarpal lig. Palmar radioulnar lig. BAnterior (palmar) view. Cut: Flexor retinaculum. Clinical box 27.4 Functional position of the hand The anatomic position of the hand, in which the palm is flat, the fingers are extended, and the forearm is supinated (palm facing forward), differs from the normal relaxed position of the hand. At rest, the forearm is in mid-supination/pronation (palm facing the body), the wrist is slightly extended, the fingers form an arcade of flexion, and the thumb is in the neutral position. Postoperative immobilization of the hand (by a cast or splint) fixes the fingers in flexion and the wrist in extension to prevent shortening of the ligaments and to maintain the ability of the hand to assume normal resting position. 30° 10° 50–60° 30° 349 Ligaments & Compartments of the Wrist Upper Limb Fig. 27.9 Ligaments and bony boundaries of the carpal tunnel Right hand, anterior (palmar) view. Hook of hamate Flexor retinaculum (transverse carpal lig.) Pisiform bone Tubercle of trapezium Carpal tunnel entrance Capitate Trapezoid Radius Ulna Ulnar carpal eminence A Carpal tunnel and flexor retinaculum. Carpometacarpal joint of the thumb Hook of hamate Pisiform Flexor retinaculum (transverse carpal lig.) Triquetrum Tubercle of trapezium Lunate Tubercle of scaphoid Radial carpal eminence B Bony boundaries of the carpal tunnel. Fig. 27.10 Carpal tunnel Right hand, transverse section. The contents of the carpal and ulnar tunnels are discussed on p. 391. Ulnar tunnel B A Palmar carpal lig. Hook of hamate Flexor retinaculum (transverse carpal lig.) Passage for flexor carpi radialis tendon Pisiform Scaphoid Triquetrum Hamate Capitate A Proximal part of the carpal tunnel. Tubercle of trapezium Passage for flexor carpi radialis tendon Carpal tunnel Carpal tunnel 350 Flexor retinaculum Hamate Trapezium Capitate Trapezoid Distal part of the carpal tunnel. B Fig. 27.11 Ulnocarpal complex Metacarpals Hamate Ulnar collateral lig. of wrist joint Midcarpal joint Hamate Trapezoid Capitate Lunate Scaphoid Radiotriquetral lig. Triquetrum Ulnar collateral lig. of wrist joint Ulnocarpal meniscus homologue Radius Triquetrum Interosseous membrane Ulnocarpal meniscus homologue Ulnocarpal disk Styloid process of ulna Dorsal radioulnar lig. Ulna Extensor carpi ulnaris muscle tendon sheath Radiocarpal joint Distal radioulnar joint Styloid process of ulna Radius Ulnotriquetral lig. Ulnolunate lig. Dorsal tubercle Lunate 27 Wrist & Hand Right hand. The ulnocarpal complex (triangular fibrocartilage complex) consists of ligaments and disks that connect the distal ulna, distal radioulnar joint, and the proximal carpal row. B Schematic of a section through the triangular fibrocartilage (ulnocarpal) complex. Radius carpal articular surface Ulnolunate lig. Ulnotriquetral lig. A Right wrist, posterior (dorsal) view. Palmar radioulnar lig. Ulnocarpal disk (triangular disk) Radius Ulnar carpal collateral lig. Ulnocarpal meniscus homologue Fig. 27.12 Compartments of the wrist Dorsal tubercle Right wrist, posterior view, schematic. Interosseous ligaments and the ulnocarpal disk divide the interarticular space into compartments. Radiotriquetral lig. Dorsal radioulnar lig. Styloid process of ulna C Right wrist, distal view. Interosseous ligs. Radial collateral lig. Pisiform Distal radioulnar joint Thumb saddle joint Ulnar collateral lig. Radiocarpal joint Carpometacarpal compartment Ulnocarpal meniscus homologue Medial carpal compartment Intermetacarpal joint Ulnocarpal disk 351 Upper Limb Ligaments of the Fingers Fig. 27.13 Ligaments of the fingers: Lateral view Right middle finger. Joint capsules, ligaments, and digital tendon sheaths. The outer fibrous layer of the tendon sheaths (stratum fibrosum) is strengthened by the anular and cruciform ligaments, which Cruciform lig. (C3) Phalangoglenoid lig. Collateral ligs. also bind the sheaths to the palmar surface of the phalanx and prevent palmar deviation of the sheaths during flexion. Cruciform lig. (C1) Phalangoglenoid lig. Collateral lig. Collateral ligs. Accessory collateral lig. 3rd metacarpal Anular ligs. (A1–A5) Deep transverse metacarpal lig. Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Flexor digitorum superficialis tendon Flexor digitorum profundus tendon Fig. 27.14 Ligaments during extension and flexion of fingers: Lateral view Proximal interphalangeal joint Distal interphalangeal joint A5 C3 A4 C2 A3 Metacarpophalangeal joint C1 A2 A Extension. Note: Whereas the 1st through 5th anular ligaments (A1–A5) have fixed positions, the cruciform ligaments (C1–C3) are highly variable in their course. A1 Phalangoglenoid lig. Collateral lig. Proximal phalanx Metacarpal bone A2 A1 B Flexion. 352 Accessory collateral lig. C Extension of the metacarpophalangeal joint. Note: The collateral ligament is lax. DFlexion of the metacarpophalangeal joint. Note: The collateral ligament is taut. Fig. 27.15 Ligaments of the fingers: Anterior (palmar) view Right middle finger. Flexor digitorum profundus tendon Fig. 27.16 Third metacarpal: Transverse section Proximal view. Cruciform lig. (C3) Extensor digitorum tendon Middle phalanx 27 Wrist & Hand Distal interphalangeal joints (collateral ligs.) Dorsal Proximal interphalangeal joints (collateral ligs.) 3rd metacarpal bone Flexor digitorum superficialis tendon Anular ligs. (A1–A5) Collateral lig. Cruciform lig. (C1) Deep transverse metacarpal lig. Palmar lig. Proximal phalanx Deep transverse metacarpal lig. Plane of section in Fig. 27.16 Flexor digitorum profundus tendon Metacarpophalangeal joint (collateral ligs.) Metacarpal bone Flexor digitorum superficialis tendon Anular lig. (A1) Flexor digitorum superficialis tendon Flexor digitorum profundus tendon A Superficial ligaments. B Deep ligaments with digital tendon sheath removed. Fig. 27.17 Fingertip: Longitudinal section The palmar articular surfaces of the phalanges are enlarged proximally at the joints by the palmar ligament. This fibrocartilaginous plate, also known as the volar plate, forms the floor of the digital tendon sheaths. Nail Tuberosity of distal phalanx Distal phalanx Distal interphalangeal joint Extensor digitorum tendon (dorsal digital expansion) Middle phalanx Palmar lig. Flexor digitorum profundus tendon 353 Upper Limb Muscles of the Hand: Superficial & Middle Layers Fig. 27.18 Intrinsic muscles of the hand: Superficial and middle layers Clinical box 27.5 Right hand, palmar surface. Dupuytren’s contracture Cruciform ligs. Anular ligs. (A1–A5) Deep transverse metacarpal lig. Superficial transverse metacarpal lig. Transverse fascicles Gradual atrophy of the palmar aponeurosis leads to progressive shortening of the palmar fascia, chiefly affecting the 4th and 5th digits. Over a period of years, the contracture may become so severe that the fingers assume a flexed position (with fingertips touching the palms), severely compromising the grasping ability of the hand. The causes of Dupuytren’s contracture are poorly understood, but it is a relatively common condition, most prevalent in men over 40 and associated with chronic liver disease (i.e., cirrhosis). Treatment generally consists of complete surgical removal of the palmar aponeurosis. Adductor pollicis Longitudinal fascicles Abductor digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis Abductor pollicis brevis Palmaris brevis Palmar aponeurosis Flexor carpi ulnaris Opponens pollicis Flexor retinaculum* Antebrachial fascia Flexor pollicis longus tendon Palmaris longus tendon A Palmar aponeurosis. *Also known as transverse carpal ligament. Flexor digitorum superficialis tendons Common flexor tendon sheath B Carpal and digital tendon sheaths. Removed: Palmar aponeurosis, palmaris longus, antebrachial fascia, and palmaris brevis. 354 Flexor digitorum profundus tendons Flexor retinaculum Pronator quadratus Flexor digitorum superficialis Flexor pollicis longus Flexor carpi radialis Clinical box 27.6 The digital tendon sheath of the thumb is continuous with the carpal tendon sheath of the flexor pollicis longus. The remaining fingers show variable communication with the carpal tendon sheaths (A is the most common variation). Infections within the tendon sheaths from puncture wounds of the fingers can track proximally to communicating spaces of the hand. Deep transverse metacarpal lig. 1st dorsal interosseus Adductor pollicis (transverse head) Lumbricals Adductor pollicis (oblique head) Flexor pollicis brevis (superficial head) Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi 27 Wrist & Hand Tendon sheath communication A B C Abductor pollicis brevis Opponens pollicis Flexor retinaculum Flexor digitorum profundus tendons Abductor pollicis longus Flexor pollicis longus tendon C Superficial layer of muscles. Removed: Tendon sheaths. Flexor digitorum superficialis tendons Flexor digitorum profundus tendons Flexor pollicis brevis (superficial head) Abductor digiti minimi Lumbricals Abductor pollicis brevis Opponens pollicis Flexor digiti minimi brevis Flexor carpi ulnaris tendon Flexor pollicis brevis (superficial head) Flexor retinaculum Abductor pollicis longus tendon DMiddle layer of muscles. Removed: Flexor digitorum superficialis, flexors carpi radialis and ulnaris, and pronator quadratus. Flexor digitorum profundus Extensor pollicis brevis Flexor carpi radialis tendon Flexor pollicis longus 355 Upper Limb Muscles of the Hand: Middle & Deep Layers Fig. 27.19 Intrinsic muscles of the hand: Middle and deep layers Right hand, palmar surface. Flexor digitorum profundus tendons Flexor pollicis longus tendon Flexor digitorum superficialis tendons Adductor pollicis (transverse head) Adductor pollicis (oblique head) Lumbricals Flexor pollicis brevis (superficial head) Abductor digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis 2nd and 3rd palmar interossei Opponens pollicis Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi Flexor retinaculum Palmar ligs. A Middle layer of muscles. Cut: Flexor digitorum profundus, lumbricals, flexor pollicis longus, and flexor digiti minimi brevis. Adductor pollicis 1st through 4th dorsal interossei Flexor pollicis brevis (superficial head) Flexor pollicis brevis (deep head) Opponens digiti minimi 1st through 3rd palmar interossei Opponens pollicis Flexor carpi ulnaris tendon Abductor pollicis longus tendon Extensor pollicis brevis B Deep layer of muscles. Cut: Opponens digiti minimi, opponens pollicis, flexor pollicis brevis, and adductor pollicis (transverse and oblique heads). 356 Flexor carpi radialis tendon Fig. 27.20 Origins and insertions of muscles of the hand Extensor digiti minimi Extensor indicis Extensor digitorum Palmar and dorsal interossei Extensor pollicis longus 27 Wrist & Hand Right hand. Muscle origins shown in red, insertions in blue. Abductor digiti minimi Extensor pollicis brevis Opponens digiti minimi Adductor pollicis Dorsal interossei Abductor pollicis longus Extensor carpi ulnaris Extensor carpi radialis brevis Extensor carpi radialis longus Flexor digitorum profundus Dorsal (posterior) view. A Flexor digitorum superficialis Interossei Flexor pollicis longus Adductor pollicis Abductor digiti minimi HG Flexor digiti minimi brevis Flexor pollicis brevis and abductor pollicis brevis FD S A 1st dorsal interosseus Flexor carpi radialis Opponens digiti minimi Opponens pollicis Extensor carpi ulnaris Abductor pollicis longus Abductor digiti minimi Abductor pollicis brevis Flexor carpi ulnaris Flexor pollicis brevis Ulna 1 1st palmar interosseus Radius 2 2nd dorsal interosseus 3 3rd dorsal interosseus 4 2nd palmar interosseus 5 4th dorsal interosseus 6 3rd palmar interosseus B Palmar (anterior) view. 357 Upper Limb Dorsum of the Hand Fig. 27.21 Extensor retinaculum and dorsal carpal tendon sheaths Fig. 27.22 Muscles and tendons of the dorsum Right hand, posterior (dorsal) view. Intertendinous connections 1st dorsal interosseus Abductor digiti minimi 2nd dorsal interosseus Dorsal carpal tendon sheaths ④ ① ⑤ Extensor carpi ulnaris Extensor digiti minimi Extensor carpi radialis longus tendon ③ Extensor pollicis longus tendon ④ Extensor pollicis brevis ⑤ Extensor Extensor digiti indicis minimi tendon tendon Extensor carpi radialis brevis tendon Extensor carpi radialis longus tendon Table 27.2 Extensor retinaculum ① Extensor carpi ⑥ ulnaris tendon ② ③ ⎧ Extensor pollicis brevis tendon ①⎨ Ulna ⎩ Abductor pollicis longus tendon Radius Extensor digitorum tendon ④ B Posterior (dorsal) compartments, proximal view of section in Fig. 27.21A. 358 Extensor digitorum Brachioradialis tendon A Right hand, posterior (dorsal) view. ⎧ ②⎨ ⎩ Extensor retinaculum Abductor pollicis longus tendon Dorsal tubercle Dorsal tubercle Extensor indicis tendon Extensor pollicis longus tendon ⑥ ③ 3rd dorsal interosseus Extensor carpi radialis brevis tendon Plane of section in Fig. 27.21B ② 4th dorsal interosseus Extensor carpi radialis longus tendon ④ Dorsal compartments for extensor tendons Abductor pollicis longus Extensor pollicis brevis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor pollicis longus Extensor digitorum Extensor indicis ⑤ Extensor digiti minimi ⑥ Extensor carpi ulnaris Fig. 27.23 Dorsal digital expansion 27 Wrist & Hand Right hand, middle finger. The dorsal digital expansion permits the long digital flexors and the short muscles of the hand to act on all three finger joints. Distal phalanx Extensor digitorum tendon Lateral bands Dorsal Dorsal digital expansion Central band 3rd metacarpal 3rd dorsal interosseus (fibers attached to extensor tendon) Collateral ligs. Lumbrical slip Deep transverse metacarpal lig. Interosseous slip 2nd dorsal interosseus 3rd dorsal interosseus (fibers attached to bone) Palmar lig. Deep transverse metacarpal lig. Plane of section in B 2nd lumbrical 2nd lumbrical Deep transverse metacarpal lig. Anular lig. (A1) Flexor digitorum superficialis tendon Flexor digitorum profundus tendon B Cross section through 3rd metacarpal head, proximal view. 3rd dorsal interosseus 2nd dorsal interosseus 3rd metacarpal Extensor digitorum tendon A Posterior view. Distal phalanx Dorsal digital expansion 2nd dorsal interosseus Interosseous slip 3rd metacarpal Extensor digitorum tendon Anular ligs. C Radial view. 2nd Lumbrical slip Flexor Flexor lumbrical digitorum digitorum superficialis profundus tendon tendon Distal Proximal interphalangeal interphalangeal Vinculum Deep transverse metacarpal lig. longum joint joint Vincula Flexor brevia digitorum profundus tendon Metacarpophalangeal joint Flexor digitorum superficialis tendon DRadial view with common tendon sheath of flexor digitorum super­ ficialis and profundus opened. 359 Upper Limb Muscle Facts (I) The intrinsic muscles of the hand are divided into three groups: the thenar, hypothenar, and metacarpal muscles (see p. 362). The thenar Table 27.3 muscles are responsible for movement of the thumb, while the ­hypothenar muscles move the 5th digit. Thenar muscles Muscle ① Adductor pollicis Origin Insertion Transverse head: 3rd metacarpal (palmar surface) Thumb (base of proximal phalanx) via the ulnar sesamoid Oblique head: capitate bone, 2nd and 3rd metacarpals (bases) ② Abductor pollicis brevis ③ Flexor pollicis brevis ④ Opponens pollicis Scaphoid bone and trapezium, flexor retinaculum Thumb (base of proximal phalanx) via the radial sesamoid Superficial head: flexor retinaculum Deep head: capitate bone, trapezium Trapezium Via the ulnar sesamoid Innervation Action Ulnar n. (C8, T1) CMC joint of thumb: adduction MCP joint of thumb: flexion Median n. (C8, T1) Via the radial sesamoid C8, T1 Superficial head: median n. (C8, T1) Deep head: ulnar n. (C8, T1) 1st metacarpal (radial border) Median n. (C8, T1) CMC joint of thumb: abduction CMC joint of thumb: flexion CMC joint of thumb: opposition CMC, carpometacarpal; MCP, metacarpophalangeal. Fig. 27.24 Thenar and hypothenar muscles Right hand, palmar (anterior) view, schematic. ① ⑤ ⑥ ③ ⑦ Table 27.4 Hypothenar muscles Muscle ⑤ Opponens digiti minimi ⑥ Flexor digiti minimi brevis Origin Insertion Innervation Action 5th metacarpal (ulnar border) Draws metacarpal in palmar direction (opposition) 5th proximal phalanx (base) MCP joint of little finger: flexion Hook of hamate, flexor retinaculum ⑦ Abductor digiti minimi Pisiform bone 5th proximal phalanx (ulnar base) and dorsal digital expansion of 5th digit Palmaris brevis Palmar aponeurosis (ulnar border) Skin of hypothenar eminence DIP, distal interphalangeal; MCP, metacarpophalangeal; PIP, proximal interphalangeal. 360 ②④ Ulnar n. (C8, T1) MCP joint of little finger: flexion and abduction of little finger PIP and DIP joints of little finger: extension Tightens the palmar aponeurosis (protective function) Fig. 27.25 Thenar and hypothenar muscles Right hand, palmar (anterior) view. 27 Wrist & Hand 5th proximal phalanx 1st proximal phalanx Transverse head Oblique head 5th metacarpal Abductor digiti minimi Adductor pollicis Abductor pollicis brevis Opponens digiti minimi Hook of hamate (under tendon) Capitate (under tendon) Pisiform (under tendon) Trapezium (under tendon) Scaphoid A Removed: Flexor pollicis brevis, opponens pollicis, and flexor digiti minimi brevis. 5th proximal phalanx Flexor digiti minimi brevis Hook of hamate (under tendon) 1st proximal phalanx Flexor pollicis brevis Opponens pollicis Capitate (under tendon) Trapezium (under tendon) B Removed: Adductor pollicis, abductor pollicis brevis, abductor digiti minimi, and opponens digiti minimi. 361 Upper Limb Muscle Facts (II) The metacarpal muscles of the hand consist of the lumbricals and ­interossei. They are responsible for the movement of the digits (with the hypothenars, which act on the 5th digit). Fig. 27.26 Metacarpal muscles of the hand Right hand, palmar view, schematic. S D F A Muscle group B Dorsal interossei. Dorsal interossei Palmar interossei Muscle ② 2nd ③ 3rd Origin Tendons of flexor digitorum profundus (radial sides) L C Palmar interossei. Insertion Innervation 2nd digit (dde) Median n. (C8, T1) 3rd digit (dde) 4th digit (dde) ④ 4th Tendons of flexor digitorum profundus (bipennate from medial and lateral sides) ⑤ 1st 1st and 2nd metacarpals (adjacent sides, two heads) 2nd digit (dde) 2nd proximal phalanx (radial side) ⑥ 2nd 2nd and 3rd metacarpals (adjacent sides, two heads) 3rd digit (dde) 3rd proximal phalanx (radial side) ⑦ 3rd 3rd and 4th metacarpals (adjacent sides, two heads) 3rd digit (dde) 3rd proximal phalanx (ulnar side) ⑧ 4th 4th and 5th metacarpals (adjacent sides, two heads) 4th digit (dde) 4th proximal phalanx (ulnar side) ⑨ 1st 2nd metacarpal (ulnar side) 2nd digit (dde) 2nd proximal phalanx (base) ⑩ 2nd 4th metacarpal (radial side) 4th digit (dde) 4th proximal phalanx (base) ⑪ 3rd 5th metacarpal (radial side) 5th digit (dde) 5th proximal phalanx (base) dde, dorsal digital expansion; IP, interphalangeal; MCP, metacarpophalangeal. 362 Ö Metacarpal muscles ① 1st Lumbricals G Ä A Lumbricals. Table 27.5 K J H 5th digit (dde) Ulnar n. (C8, T1) Action 2nd to 5th digits: • MCP joints: flexion • Proximal and distal IP joints: extension 2nd to 4th digits: • MCP joints: flexion • Proximal and distal IP joints: extension and abduction from 3rd digit 2nd, 4th, and 5th digits: • MCP joints: flexion • Proximal and distal IP joints: extension and adduction toward 3rd digit Fig. 27.27 Metacarpal muscles Right hand, palmar (anterior) view. 27 Wrist & Hand 2nd distal phalanx, base 2nd proximal phalanx 2nd metacarpal 1st lumbrical 2nd lumbrical 3rd lumbrical (often arises by two heads) 4th lumbrical (often arises by two heads) Hook of hamate Trapezoid Pisiform Radius Ulna Flexor digitorum profundus tendons 2nd through 5th proximal phalanges 3rd dorsal interosseus 2nd dorsal interosseus 4th dorsal interosseus 1st dorsal interosseus 2nd through 5th metacarpals 1st metacarpal A Lumbrical muscles. B Dorsal interosseus muscles. 1st palmar interosseus 2nd palmar interosseus 3rd palmar interosseus 2nd through 5th metacarpals C Palmar interosseus muscles. 363 28 Neurovasculature Upper Limb Arteries of the Upper Limb Fig. 28.1 Arteries of the upper limb Right limb with the forearm supinated, anterior view. Vertebral a. Subclavian a. Brachiocephalic trunk Subclavian a. Axillary a. Acromial br. Thoracoacromial a. Brachial a. Thyrocervical trunk Left common carotid a. Suprascapular a. Left subclavian a. Brachiocephalic trunk Deltoid br. Pectoral br. Superior thoracic a. Axillary a. Thoracic aorta Internal thoracic a. Anterior and posterior circumflex humeral aa. Radial a. Ulnar a. Subscapular a. Circumflex scapular a. Deep a. of arm Thoracodorsal a. Brachial a. Lateral thoracic a. Radial collateral a. Middle collateral a. Radial recurrent a. A Main arterial segments. Superior and inferior ulnar collateral aa. Ulnar recurrent a. Common interosseous a. Posterior interosseous a. Radial a. Anterior interosseous a. Ulnar a. Superficial palmar br. (radial a.) Deep palmar arch Superficial palmar arch Common palmar digital aa. Palmar digital aa. B Course of the arteries. 364 Fig. 28.2 Branches of the subclavian artery Fig. 28.3 Scapular arcade Right side, anterior view. Right side, posterior view. Superficial cervical a. (superficial br.) Vertebral a. Dorsal scapular a. (deep br.) Anterior scalene Transverse cervical a. Inferior thyroid a. Middle scalene Posterior scalene Common carotid a. Suprascapular a. Thyrocervical trunk Axillary a. Subclavian a. Thyrocervical trunk Suprascapular a. Transverse cervical a. Acromial brs. Circumflex scapular a. Axillary a. Anterior circumflex humeral a. Posterior circumflex humeral a. Dorsal scapular a. Subscapular a. Deep a. of arm Costocervical trunk Subclavian a. Thoracodorsal a. Clavicle Deep cervical a. 28 Neurovasculature Vertebral a. Ascending cervical a. Brachial a. 1st rib Supreme intercostal a. Internal thoracic a. Fig. 28.4 Arteries of the forearm and hand Right limb. The ulnar and radial arteries are interconnected by the super­ficial and deep palmar arches, the perforating branches, and the dorsal carpal network. Recurrent interosseous a. Posterior interosseous a. Common Common interosseous a. interosseous a. Anterior interosseous a. Dorsal Posterior interosseous a. Radial a. Dorsal carpal network Palmar carpal network Dorsal carpal a. Perforating br. Dorsal metacarpal a. Dorsal and palmar digital aa. Ulnar a. Palmar Deep palmar arch Radial a. Deep palmar arch Anterior interosseous a. Interosseous Interosseous membrane membrane Palmar carpal brs. (to palmar carpal network) Superficial palmar arch Metacarpal Princeps palmar a. pollicis a. Superficial palmar arch Proper palmar digital aa. Anterior interosseous a. (posterior br.) Ulnar a. (dorsal carpal br.) Dorsal carpal network Radial a. Dorsal carpal a. Dorsal metacarpal aa. Perforating brs. Common palmar digital aa. Radialis indicis a. Palmar digital aa. Right middle finger, lateral view. A Posterior interosseous a. Anterior (palmar) view. B Dorsal digital aa. Posterior (dorsal) view. C 365 Upper Limb Veins & Lymphatics of the Upper Limb Fig. 28.5 Veins of the upper limb Fig. 28.6 Veins of the dorsum Right limb, anterior view. Deltopectoral groove Right hand, posterior view. Axillary v. Cephalic v. Subscapular v. Cephalic v. Basilic v. Basilic v. Basilic hiatus Dorsal venous network Brachial vv. Basilic v. Intercapitular vv. Dorsal digital vv. Median cubital v. Median antebrachial v. Basilic v. Cephalic v. Perforator vv. Anterior interosseous vv. Ulnar vv. Radial vv. Superficial palmar venous arch Deep palmar venous arch Palmar metacarpal vv. Intercapitular vv. Palmar digital vv. A Superficial veins. B Deep veins. Clinical box 28.1 Venipuncture The veins of the cubital fossa are frequently used when drawing blood. In preparation, a tourniquet is applied above the cubital fossa. This allows arterial blood to flow, but blocks the return of venous blood. The resulting swelling makes the veins more visible and palpable. Fig. 28.7 Cubital fossa Right limb, anterior view. The subcutaneous veins of the cubital fossa have a highly variable course. Cephalic v. Median antebrachial v. Basilic v. Median cephalic v. Median cubital v. Deep median cubital v. Basilic v. A M -shaped. 366 Cephalic v. Accessory cephalic v. Median cephalic v. Cephalic v. B Accessory cephalic vein. Median cubital v. Perforator v. Median basilic v. Median basilic v. Basilic v. Basilic v. Median antebrachial v. Median antebrachial v. C Absent median cubital vein. Lymph from the upper limb and breast drains to the axillary lymph nodes. The superficial lymphatics of the upper limb lie in the subcutaneous t­ issue, while the deep lymphatics accompany the arteries and deep veins. Numerous anastomoses exist between the two systems. 28 Neurovasculature Fig. 28.8 Lymph vessels of the upper limb Right limb. Axillary lymph nodes Dorsolateral arm territory Dorsolateral arm territory Dorsomedial arm territory Middle arm territory Cubital l.n. Radial bundle territory Ulnar bundle territory Radial bundle territory Middle forearm territory Radial group of lymphatics Ulnar group of lymphatics Dorsal descending lymphatics Anterior view. A Fig. 28.9 Lymphatic drainage of the hand Right hand, radial view. Most of the hand drains to the axillary nodes via cubital nodes. However, the thumb, index finger, and dorsum of the hand drain directly. Lymph vessels ascending from the palmar to dorsal side Posterior view. B Fig. 28.10 Axillary lymph nodes Right side, anterior view. For surgical purposes, the axillary lymph nodes are divided into three levels with respect to their relationship with the pectoralis minor: lateral (level I), posterior (level II), or medial (level III). They have major clinical importance in breast cancer (see p. 76). Level I Level II Right lymphatic duct Radial bundle territory Level III Radial group of lymphatics Pectoralis minor 367 Upper Limb Nerves of the Upper Limb: Brachial Plexus Almost all muscles in the upper limb are innervated by the brachial plexus, which arises from spinal cord segments C5 to T1. The anterior rami of the spinal nerves give off direct branches (supraclavicular part of the brachial plexus) and merge to form three trunks, six divisions (three anterior and three posterior), and three cords. The infraclavicular part of the brachial plexus consists of short branches that arise directly from the cords and long (terminal) branches that traverse the limb. Dorsal scapular n. Suprascapular n. Table 28.1 C5 Supraclavicular part Posterior cord Lateral cord Direct branches from the anterior rami or plexus trunks Medial cord T1 Subscapular n. Phrenic n. Axillary a. N. to the subclavius Axillary n. C5, C6 N. to the subclavius C5–C6 Long thoracic n. C5–C7 Lateral pectoral n. Medial brachial cutaneous n. Lateral cord Musculocutaneous n. Median n. Medial and lateral pectoral nn. Median n. Lateral root Medial cord Thoracodorsal n. Posterior cord Anterior interosseous n. C6–C7 C8–T1 Medial antebrachial cutaneous n. Medial brachial cutaneous n. Ulnar n. C5–C7 Medial root Medial pectoral n. Radial n. Superficial br. C4–C5 Suprascapular n. Short and long branches from the plexus cords Musculocutaneous n. Deep br. Dorsal scapular n. Infraclavicular part Long thoracic n. Radial n. Nerves of the brachial plexus T1 Ulnar n. C7–T1 Upper subscapular n. C5–C6 Thoracodorsal n. C6–C8 Lower subscapular n. Axillary n. Radial n. C5–C6 C5–T1 Clinical box 28.2 Injuries to nerves of the brachial plexus Injuries of the brachial plexus can be complicated to diagnose but an understanding of the basic organization of the plexus is essential. The location of the injury can be determined by careful examination of the type and specificity of the deficit. Nerves of the upper plexus innervate muscles of the proximal limb such as those of the shoulder girdle and arm, while nerves of the lower plexus innervate muscles of the distal limb, such as the forearm and hand. Symptoms from injuries at the root and cord levels will demonstrate this anatomical arrangement. Additionally, a proximal injury to a nerve will elicit more broad-ranging symptoms than a distal injury to that nerve. 368 Fig. 28.11 Brachial plexus Posterior root Anterior root Right side, anterior view. 28 Neurovasculature Posterior rami C5 Anterior rami C6 Upper trunk (C5–C6) C7 Middle trunk (C7) C8 Lower trunk (C8–T1) T1 Anterior divisions of C5–C7 Posterior divisions of C5–T1 Lateral cord Anterior divisions of C8–T1 Posterior cord Medial cord Axillary a. Axillary n. Lateral root Musculocutaneous n. Ulnar n. Radial n. Medial root C5 spinal n. Median n. Middle scalene Dorsal scapular n. Phrenic n. Anterior scalene Upper trunk Median n. A Structure of the brachial plexus. Middle trunk Suprascapular n. Vertebra prominens (C7) C8 spinal n. Lower trunk T1 spinal n. Interscalene space Common carotid a. Posterior cord Subclavian a. Lateral cord Brachiocephalic trunk Subscapular n. N. to the subclavius Medial cord 1st rib Long thoracic n. Axillary a. Axillary n. Intercostobrachial n. Posterior circumflex humeral a. Musculocutaneous n. Medial brachial cutaneous n. Medial pectoral n. Radial n. Median n. B Course of the brachial plexus, stretched for clarity. Medial antebrachial cutaneous n. Ulnar n. Thoracodorsal n. Lateral pectoral n. 369 Upper Limb Supraclavicular Branches & Posterior Cord Fig. 28.12 Supraclavicular branches The supraclavicular branches of the brachial plexus arise directly from the plexus roots (anterior rami of the spinal nerves) or from the plexus trunks in the lateral cervical triangle. Right shoulder. Transverse process of atlas (C1) Dorsal scapular n. Levator scapulae Vertebra prominens (C7) Scapula, superior angle Rhomboid minor Rhomboid major Scapula, medial border Suprascapular n. C4 spinal n. Superior transverse lig. of scapular Suprascapular n. in the scapular notch Acromion A Dorsal scapular nerve. Posterior view. Supraspinatus Greater tubercle Scapular spine Atlas (C1) Infraspinatus C5 spinal n. N. to the subclavius Vertebra prominens (C7) B Suprascapular nerve. Posterior view. Clavicle Subclavius 1st rib Serratus anterior Long thoracic n. Table 28.2 9th rib C Long thoracic nerve and nerve to the subclavius. Right lateral view. 370 Supraclavicular branches Nerve Level Innervated muscle Dorsal scapular n. C4–C5 Levator scapulae Rhomboids major and minor Suprascapular n. C5, C6 Supraspinatus Infraspinatus N. to the subclavius C5–C6 Subclavius Long thoracic n. C5–C7 Serratus anterior The posterior cord gives off three short branches (arising at the level of the plexus cords) and two long branches (terminal nerves, see pp. 372–373). Right shoulder. C5 spinal n. Subscapularis 28 Neurovasculature Fig. 28.13 Posterior cord: Short branches Posterior cord Teres major 2nd rib (cut) Upper subscapular n. C6 spinal n. Lower subscapular n. T7 spinous process Thoracodorsal n. A Subscapular nerves. Anterior view. Latissimus dorsi T12 spinous process Thoracolumbar fascia Table 28.3 Iliac crest Branches of the posterior cord Nerve Level Innervated muscle Short branches Upper subscapular n. Subscapularis C5–C6 Subscapularis Teres major C6–C8 Latissimus dorsi Axillary n. C5–C6 See p. 372 Radial n. C5–T1 See p. 373 Lower subscapular n. Thoracodorsal n. Sacrum B Thoracodorsal nerve. Posterior view. Long (terminal) branches 371 Upper Limb Posterior Cord: Axillary & Radial Nerves Fig. 28.14 Axillary nerve: Cutaneous distribution Right limb. Clinical box 28.3 The axillary nerve may be damaged in a fracture of the surgical neck of the humerus. This results in limited ability to abduct the arm and may cause a loss of profile of the shoulder. Supraclavicular nn. Superior lateral brachial cutaneous n. (axillary n.) Fig. 28.15 Axillary nerve Right side, anterior view, stretched for clarity. Atlas (C1) C5 spinal n. Middle scalene Phrenic n. Anterior scalene A Anterior view. B Posterior view. Axillary a. Deltoid Superior lateral brachial cutaneous n. (terminal sensory br. of axillary n.) Axillary n. Table 28.4 Axillary nerve (C5–C6) Motor branches Innervated muscles Muscular brs. Deltoid Teres minor Sensory branch Superior lateral brachial cutaneous n. 372 Teres minor Posterior cord Fig. 28.16 Radial nerve: Cutaneous distribution Fig. 28.17 Radial nerve Right limb, anterior view with forearm pronated. Posterior brachial cutaneous n. Posterior cord Axillary a. Radial n. Inferior lateral brachial cutaneous n. 28 Neurovasculature Anterior scalene Posterior brachial cutaneous n. Posterior antebrachial cutaneous n. Radial n. (in radial groove) Inferior lateral brachial cutaneous n. Triceps brachii Radial n., superficial br. Radial tunnel Posterior antebrachial cutaneous n. A Anterior view. Table 28.5 B Posterior view. Radial nerve (C5–T1) Motor branches Innervated muscles Brachialis (partial) Triceps brachii Muscular brs. Anconeus Brachioradialis Supinator Brachialis Radial n., deep br. (in supinator canal) Posterior interosseous n. Brachioradialis Radialis muscle group Radial n., superficial br. Abductor pollicis longus Extensor digitorum Extensor pollicis brevis Extensor pollicis longus Extensors carpi radialis longus and brevis Supinator Dorsal digital nn. Extensor digitorum Deep br. (terminal br.: posterior interosseous n.) Extensor digiti minimi Extensor carpi ulnaris Extensors pollicis brevis and longus Extensor indicis Abductor pollicis longus Sensory branches Articular brs. from radial n.: Capsule of the shoulder joint Articular brs. from posterior interosseous n.: Joint capsule of the wrist and four radial metacarpophalangeal joints Posterior brachial cutaneous n. Inferior lateral brachial cutaneous n. Posterior antebrachial cutaneous n. Superficial brs. Dorsal digital nn. Ulnar communicating br. Clinical box 28.4 Chronic radial nerve compression in the axilla (e.g., due to extended/ improper crutch use) may cause loss of sensation or motor function in the hand, forearm, and posterior arm. More distal injuries (e.g., during anesthesia) affect fewer muscles, potentially resulting in wrist drop with intact triceps brachii function. 373 Upper Limb Medial & Lateral Cords The medial and lateral cords give off four short branches. The inter­ costobrachial nerves are included with the short branches of the Table 28.6 Branches of the medial and lateral cords Nerve Level Cord Innervated muscle Lateral pectoral n. C5–C7 Lateral cord Pectoralis major Medial pectoral n. C8–T1 Medial brachial cutaneous n. T1 Medial antebrachial cutaneous n. C8–T1 Intercostobrachial nn. T2–T3 brachial plexus, although they are actually the cutaneous branches of the 2nd and 3rd intercostal nerves. Fig. 28.18 Medial and lateral cords: Short branches Right side, anterior view. Short branches Pectoralis major and minor Medial cord — (sensory brs., do not innervate any muscles) C5–C7 Median n. C6–T1 Ulnar n. C7–T1 C7 spinal n. Medial pectoral n. Long (terminal) branches Musculocutaneous n. Brachial plexus (C5–T1) Lateral cord Medial cord Coracobrachialis Biceps brachii Brachialis Pectoralis minor Lateral pectoral n. See p. 376 Medial cord See p. 377 Pectoralis major Fig. 28.19 Short branches of medial and lateral cords: Cutaneous distribution Medial and lateral pectoral nerves. A Medial brachial cutaneous n., intercostobrachial n. Posterior ramus Medial antebrachial cutaneous n. Intercostobrachial nn. Anastomosis with medial brachial cutaneous n. Intercostobrachial nerves. B A Anterior view. 374 B Posterior view. 2nd and 3rd intercostal nn. T3 vertebral body Anterior cutaneous br. of 2nd intercostal n. Lateral cutaneous br. of 4th intercostal n. Fig. 28.20 Musculocutaneous nerve Table 28.7 Right limb, anterior view. Lateral cord Anterior scalene Motor branches Coracobrachialis Muscular brs. Intertubercular groove Innervated muscles Biceps brachii Brachialis Sensory branches Lateral antebrachial cutaneous n. Axillary a. Articular brs.: Joint capsule of the elbow (anterior part) Musculocutaneous n. 28 Neurovasculature Coracoid process Musculocutaneous nerve (C5–C7) Note: Musculocutaneous n. innervation of the arm is purely motor; innervation of the forearm is purely sensory. Biceps brachii, short head Biceps brachii, long head Coracobrachialis Brachialis Biceps brachii Musculocutaneous n. Fig. 28.21 Musculocutaneous nerve: Cutaneous distribution Brachialis Lateral antebrachial cutaneous n. Lateral antebrachial cutaneous n. Ulna Radius A Anterior view. B Posterior view. 375 Upper Limb Median & Ulnar Nerves The median nerve is a terminal branch arising from both the medial and the lateral cords. The ulnar nerve arises exclusively from the medial cord. Fig. 28.22 Median nerve Lateral cord Fig. 28.23 Median nerve: Cutaneous distribution Anterior scalene Right limb, anterior view. Medial cord Axillary a. Lateral root Median n. Medial root Median n., palmar branch Median n. Common and proper palmar digital nn. Proper palmar digital nn. A Anterior view. B Posterior view. Medial epicondyle Table 28.8 Articular br. Pronator teres, humeral head Median nerve (C6–T1) Motor branches Pronator teres Flexor carpi radialis Pronator teres, ulnar head Anterior interosseous n. Flexor pollicis longus Recurrent br. Palmaris longus Muscular brs. from anterior interosseous n. Flexor digitorum profundus Recurrent br. Median n., palmar br. 1st and 2nd lumbricals Proper palmar digital nn. Palmaris longus Pronator quadratus Flexor pollicis longus Flexor digitorum profundus (radial half) Abductor pollicis brevis Pronator quadratus Flexor pollicis brevis (superficial head) Opponens pollicis Flexor retinaculum 376 Flexor carpi radialis Direct muscular brs. Flexor digitorum superficialis Flexor digitorum superficialis Common palmar digital nn. Innervated muscles Muscular brs. from common palmar digital nn. Clinical box 28.5 Median nerve injury caused by fracture/ dislocation of the elbow joint may result in compromised grasping ability and sensory loss in the fingertips (see Fig. 28.23 for territories). See also carpal tunnel syndrome (p. 391). 1st and 2nd lumbricals Sensory branches Articular brs.: Capsules of the elbow and wrist joints Palmar br. of median n. (thenar eminence) Communicating br. to ulnar n. Common palmar digital nn. Proper palmar digital nn. Fig. 28.24 Ulnar nerve: Cutaneous distribution Fig. 28.25 Ulnar nerve Right limb, anterior view. 28 Neurovasculature Medial cord Axillary a. Ulnar n. Ulnar n., palmar br. Ulnar n., dorsal br. Common and proper Dorsal palmar digital nn. digital nn. A Anterior view. Table 28.9 Medial epicondyle B Posterior view. Ulnar groove Ulnar nerve (C7–T1) Motor branches Innervated muscles Flexor carpi ulnaris Direct muscular brs. Muscular br. from superior ulnar n. Flexor carpi ulnaris Flexor digitorum profundus (ulnar half) Palmaris brevis Abductor digiti minimi Flexor digiti minimi brevis Muscular brs. from deep ulnar n. Flexor digitorum profundus Flexor retinaculum Dorsal br. Palmar br. Opponens digiti minimi Superficial br. 3rd and 4th lumbricals Deep br. Palmar and dorsal interosseous muscles 4th common palmar digital n. Adductor pollicis Interossei Flexor pollicis brevis (deep head) Sensory branches Articular brs.: Capsules of the elbow, carpal, and metacarpophalangeal joints Dorsal br. (terminal brs.: dorsal digital nn.) Palmar br. Proper palmar digital n. (from superficial br.) Common palmar digital n. (from superficial br.; terminal brs.: proper palmar digital nn.) Proper palmar digital nn. Clinical box 28.6 Ulnar nerve palsy is the most common peripheral nerve damage. The ulnar nerve is most vulnerable to trauma or chronic compression in the elbow joint and ulnar tunnel (see p. 391). Nerve damage causes “clawing” of the hand and atrophy of the interossei. Sensory losses are often limited to the 5th digit. 377 Upper Limb Superficial Veins & Nerves of the Upper Limb Fig. 28.26 Superficial cutaneous veins and nerves of the upper limb Supraclavicular nn. Supraclavicular nn. Superior lateral brachial cutaneous n. (axillary n.) Intercostal nn., anterior cutaneous brs. Intercostobrachial n. Medial brachial cutaneous n. Cephalic v. Inferior lateral brachial cutaneous n. (radial n.) Superior lateral brachial cutaneous n. (axillary n.) Intercostobrachial n. Medial brachial cutaneous n. Posterior brachial cutaneous n. (radial n.) Basilic hiatus Inferior lateral brachial cutaneous n. (radial n.) Basilic v. Medial antebrachial cutaneous n. Lateral antebrachial cutaneous n. (musculocutaneous n.) Median cubital v. Cephalic v. Median antebrachial v. Posterior antebrachial cutaneous n. (radial n.) Basilic v. Medial antebrachial cutaneous n. Lateral antebrachial cutaneous n. (musculocutaneous n.) Accessory cephalic v. Perforating brs. Medial antebrachial cutaneous n. Cephalic v. Radial n., superficial br. Radial n., superficial br. Ulnar n., palmar br. Ulnar n., dorsal br. Median n., palmar br. Dorsal venous network Palmar aponeurosis Intercapitular vv. Dorsal digital vv. A Anterior view. See pp. 392–393 for nerves of the palm. 378 B Posterior view. See pp. 394–395 for nerves of the dorsum. Fig. 28.27 Cutaneous innervation of the upper limb Axillary n. Medial brachial cutaneous n., intercostobrachial n. Medial antebrachial cutaneous n. Radial n. Musculocutaneous n. Axillary n. Medial brachial cutaneous n., intercostobrachial n. Musculocutaneous n. Dorsal br. Ulnar n. Common and proper palmar digital nn. Radial n. Medial antebrachial cutaneous n. Palmar br. Palmar br. Median n. Supraclavicular nn. 28 Neurovasculature Supraclavicular nn. Anterior cutaneous brs. Intercostal nn. Lateral cutaneous brs. Ulnar n. Dorsal digital nn. Common and proper palmar digital nn. A Anterior view. Proper palmar digital nn. (median n.) B Posterior view. Fig. 28.28 Dermatomes of the upper limb C4 T2 C5 T2 T3 T3 T4 T4 T5 C4 C5 T5 C6 T1 T1 C6 C7 C7 C8 C8 A Anterior view. B Posterior view. 379 Upper Limb Posterior Shoulder & Arm Fig. 28.29 Posterior shoulder Right shoulder, posterior view. Raised: Trapezius (transverse part). Windowed: Supraspinatus. Revealed: Suprascapular region. Trapezius, descending part Omohyoid Supraclavicular nn. Posterior rami of spinal nn., medial brs. Suprascapular a. (with superior transverse lig. of scapula) Suprascapular n. (in scapular notch) Trapezius, transverse part Coracoclavicular lig. Supraspinatus Accessory n. and brs. of cervical plexus Scapular spine Deltoid Posterior rami of spinal nn., lateral brs. Teres minor Superior lateral brachial cutaneous n. (axillary n.) Trapezius (ascending part) Inferior lateral brachial cutaneous n. (radial n.) Latissimus dorsi 380 Infraspinatus Teres major Posterior brachial cutaneous n. (radial n.) Table 28.10 Superior transverse lig. of scapula ① Transmitted structures Boundaries ② ① Scapular notch Superior transverse lig. of scapula, scapula Suprascapular a., v. and n. ② Medial border Scapula Dorsal scapular a., v. and n. ③ Triangular space Teres major and minor, triceps brachii Circumflex scapular a. and v. ⑤ ④ Triceps hiatus Triceps brachii, humerus, teres major Deep a. and v. of arm and radial n. ④ ⑤ Quadrangular space Teres major and minor, triceps brachii, humerus Posterior circumflex humeral a. and v. and axillary n. Inferior transverse lig. of scapula 28 Neurovasculature Passageway Neurovascular tracts of the scapula ③ Fig. 28.30 Triangular and quadrangular spaces Clavicle ARight shoulder, posterior view. Windowed: Deltoid. Supraspinatus Acromion Scapular spine Suprascapular a. and n. in scapular notch Shoulder joint capsule Infraspinatus Teres minor Deltoid Medial border scapula Axillary n. and posterior circumflex humeral a. in quadrangular space Triceps brachii, lateral head Circumflex scapular a. in triangular space Teres major Radial n., muscular brs. Deep a. of arm and radial n. (in radial groove) Triceps brachii Long head Lateral head In triceps hiatus Lateral intermuscular septum B Right shoulder, posterior view. Windowed: Infraspinatus, triceps brachii (lateral head). 381 Upper Limb Anterior Shoulder Fig. 28.31 Anterior shoulder: Superficial dissection Right shoulder. Clavicle Subclavius Superficial thoracic fascia Subclavian v. Pectoralis minor Clavipectoral fascia Pectoralis major Axillary fascia A Sagittal section through anterior wall. External jugular v. Great auricular n. Middle scalene m. Posterior scalene m. Supraclavicular nn. Infraclavicular fossa Trapezius Deltoid Transverse cervical n. Sternocleidomastoid Brachial plexus Omohyoid, inferior belly Subclavian v. Pectoralis major (clavicular part) Cephalic v. (in deltopectoral groove) Clavipectoral fascia Thoracoacromial a. Medial pectoral n. Lateral pectoral n. Pectoralis major (sternocostal part) Biceps brachii Brachial fascia Latissimus dorsi B Anterior view. Removed: Platysma, muscle fasciae, superficial layer of cervical fascia, and pectoralis major (clavicular part). Revealed: Clavipectoral triangle. 382 Fig. 28.32 Shoulder: Transverse section Right shoulder, inferior view. Subtendinous Tendon of bursa of biceps brachii, subscapularis long head Deltoid Pectoralis major Pectoralis minor Coracobrachialis Anterior Axillary a. and v., cords of brachial plexus Subscapularis 28 Neurovasculature Subdeltoid bursa Head of humerus Deltoid Ribs Serratus anterior Posterior Glenoid labrum Glenoid cavity Infraspinatus Rhomboid major Scapula Fig. 28.33 Anterior shoulder: Deep dissection Right limb, anterior view. Removed: Sternocleidomastoid, omohyoid, and pectoralis major. This dissection reveals the neurovascular contents of the lateral cervical triangle (see pp. 538–539) and axilla (see pp. 384–385). Suprascapular a. Axillary a. Thoracoacromial a. Trapezius Omohyoid, inferior belly (cut) Interscalene space Brachial plexus Internal jugular v. Common carotid a. Scalene mm. Phrenic n. Inferior thyroid a. Ascending cervical a. Transverse cervical a. Deltoid External jugular v. Thyrocervical trunk Cephalic v. Subclavian v. Musculocutaneous n. Clavicle Pectoralis major (cut) Subclavius Superior thoracic a. Median n. Long thoracic n. Ulnar n. Axillary a. and v. Pectoralis major Pectoralis minor Circumflex scapular a. Thoracodorsal a. Subscapular a. Lateral thoracic a. Medial and lateral pectoral nn. 383 Upper Limb Axilla Fig. 28.34 Axilla: Dissection Right shoulder, anterior view. Median n. roots Musculocutaneous n. Thoracoacromial a. Lateral cord Axillary a. and v. Subclavius Long thoracic n., superior thoracic a. Deltoid Cephalic v. Pectoralis major Lateral pectoral n. Medial pectoral n. Lateral thoracic a. Biceps brachii Median n. Ulnar n. Brachial a. and v. Pectoralis major Circumflex scapular a. Lower subscapular n. Long thoracic n. Thoracodorsal a. and n. A Removed: Pectoralis major and clavipectoral fascia. Table 28.11 Walls of the axilla Anterior wall Pectoralis major Pectoralis minor Clavipectoral fascia Lateral wall Intertubercular groove of humerus Posterior wall Subscapularis Teres major Latissimus dorsi Medial wall Lateral thoracic wall Serratus anterior Medial and lateral cords Pectoralis major Coracobrachialis Biceps brachii, short head Serratus anterior Biceps brachii, long head Subscapularis Axillary a. and v. Rib Head of humerus Posterior cord 384 Pectoralis minor Scapula Thoracoacromial a. Medial and lateral cord brs. Lateral cord Axillary a. Radial n. Medial cord Axillary v. Brachial a. 28 Neurovasculature Subscapular a. Long thoracic n., superior thoracic a. Upper subscapular n. Lateral thoracic a. Lower subscapular n. Median n. Ulnar n. Axillary n. Brachial v. Thoracodorsal a. and n. Radial n., motor brs. B Removed: Anterior wall (pectoralis major and minor, and clavipectoral fascia). Retracted: Medial and lateral cords of the brachial plexus. Circumflex scapular a. Posterior cord Deltoid Biceps brachii tendon of long head Coracoid process Pectoralis major Pectoralis minor Deltoid Lateral and medial cords Coracobrachialis Suprascapular n. (in scapular notch) Radial n. Upper subscapular n. Lower subscapular n. Biceps brachii Subscapularis Biceps fascia Thoracodorsal n. Posterior brachial cutaneous n. Removed: Medial and C lateral cords, and axillary vessels. Revealed: Posterior cord. Radial n., motor brs. Medial head Long head Triceps brachii Axillary n. Serratus anterior Latissimus dorsi Teres major 385 Upper Limb Anterior Arm & Cubital Region Fig. 28.35 Brachial region Right arm, anterior view. Removed: Deltoid, pectoralis major and minor. Revealed: Medial bicipital groove. Musculocutaneous n. (piercing the Coracoid coracobrachialis) process Biceps brachii tendon of long head Lateral cord Pectoralis major Axillary a. and v. Deltoid Medial cord Median n. Medial intermuscular septum Bicipital aponeurosis Pectoralis minor Medial brachial cutaneous n. Biceps brachii Medial antebrachial cutaneous n. Brachial a. Subscapularis Cubital fossa Ulnar n. Superior ulnar collateral a. Posterior brachial cutaneous n. Teres major Long head Brachialis Ulnar n. (in ulnar groove) 386 Medial head Inferior ulnar collateral a. Triceps brachii Latissimus dorsi Serratus anterior Fig. 28.36 Cubital region Right elbow, anterior view. Skin 28 Neurovasculature Subcutaneous tissue Basilic v. Biceps brachii Cephalic v. Medial antebrachial cutaneous n. Medial epicondyle Median cubital v. Lateral antebrachial cutaneous n. Deep median cubital v. (perforator v.) Median basilic v. Cephalic v. Biceps brachii Brachialis Basilic v. Median antebrachial v. Radial tunnel Brachial a., median n. Triceps brachii Musculocutaneous n. Brachioradialis A Cutaneous neurovascular structures in the cubital fossa. Muscular brs. Deep Radial n. br. Superficial br. Medial antebrachial Superficial fascia cutaneous n. Biceps brachii tendon Radial recurrent a. Ulnar a. Cephalic v. Basilic v. Biceps brachii (and fascia) Brachial a. and v. Median n. Brachialis Lateral antebrachial cutaneous n. (musculocutaneous n.) Biceps brachii tendon Supinator Inferior ulnar collateral a. Superior ulnar collateral a., ulnar n. Pronator teres Perforator v. Radial a. Extensor carpi radialis longus Radial a. Pronator teres Superior ulnar collateral a., ulnar n. Median n. Humeral head Ulnar head Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris C Deep cubital fossa. Removed: Biceps brachii (distal muscle belly). Retracted: Brachio­ radialis. Bicipital aponeurosis Brachioradialis Cephalic v. Median antebrachial v. B Superficial cubital fossa. Removed: Fasciae and epifascial neurovascular structures. 387 Upper Limb Anterior & Posterior Forearm Fig. 28.37 Anterior forearm Right forearm, anterior view. Median n. Median n. Triceps brachii Biceps brachii Inferior ulnar collateral a. Superior ulnar collateral a., ulnar n. Brachialis Medial epicondyle Brachial a. Biceps brachii tendon Pronator teres Biceps brachii Superior ulnar collateral a., ulnar n. Brachialis Inferior ulnar collateral a. Brachioradialis Medial epicondyle Radial n., superficial br. Radial a. Flexor carpi radialis Biceps brachii tendon Brachioradialis Bicipital aponeurosis Common interosseous a. Palmaris longus Posterior interosseous a. Pronator teres, humeral head Flexor carpi radialis Palmaris longus Pronator teres, ulnar head Recurrent interosseous a. Flexor digitorum superficialis Anterior interosseous a. Extensor carpi radialis brevis Flexor carpi ulnaris Extensor carpi radialis longus Pronator teres Flexor carpi ulnaris Flexor carpi radialis Radial a. Abductor pollicis longus Flexor digitorum superficialis Radial a. Palmaris longus tendon Ulnar a. Flexor pollicis longus Median n. Flexor pollicis longus Abductor pollicis longus Median n. Pronator quadratus Flexor digitorum superficialis tendons Ulnar a. and n. Flexor retinaculum Flexor carpi radialis tendon Ulnar n. (in ulnar tunnel) Hypothenar muscles Thenar muscles Palmar aponeurosis A Superficial layer. Removed: Fasciae and superficial neurovasculature. 388 Hypothenar muscles Thenar muscles Palmar br. of median n. B Middle layer. Partially removed: Superficial flexors (pronator teres, flexor digitorum superficialis, palmaris longus, and flexor carpi radialis). Fig. 28.38 Posterior forearm Right forearm, anterior view during pronation. Reflected: Anconeus and triceps brachii. Removed: Extensor carpi ulnaris and extensor digitorum. Triceps brachii, lateral head Biceps brachii Musculocutaneous n. Muscular brs. Radial n. Brachial a. Radial collateral a. Olecranon Brachialis Superficial br. Deep br. Anconeus Biceps brachii tendon Brachioradialis Pronator teres Extensor carpi ulnaris Interosseous recurrent a. Radial a. Flexor digitorum superficialis, humeroulnar head Ulnar a. and n. Passage through interosseous membrane Arterial network of elbow and lateral epicondyle Supinator Extensor digitorum Posterior interosseous n. Posterior interosseous a. Extensor carpi ulnaris Anterior interosseous a. (piercing the membrane) Median n. Flexor pollicis longus Extensor indicis Abductor pollicis longus Interosseous membrane Radial a. Extensor carpi radialis longus Extensor carpi radialis brevis and longus Flexor digitorum superficialis, radial head Pronator quadratus Brachioradialis 28 Neurovasculature Median n. Flexor digitorum profundus tendons Ulnar a. and n. Flexor digitorum superficialis tendons Ulnar a., dorsal carpal br. Extensor retinaculum Radial a., dorsal carpal br. Extensor carpi radialis brevis tendon Extensor pollicis longus Abductor pollicis longus Extensor pollicis brevis Extensor carpi radialis longus tendon Radial a. Extensor pollicis longus tendon C Deep layer. Removed: Deep flexors. 389 Upper Limb Carpal Region Fig. 28.39 Anterior carpal region Superficial palmar arch Right hand, anterior (palmar) view. Median n., recurrent br. Flexor digiti minimi brevis Flexor pollicis brevis, superficial head Abductor digiti minimi Abductor pollicis brevis Palmaris brevis Opponens pollicis Palmar aponeurosis (cut) Flexor retinaculum (transverse carpal lig.) Pisiform Radial a., superficial palmar br. Ulnar tunnel Median n. Palmar carpal lig. Pronator quadratus Ulnar a. and n. Flexor carpi radialis Flexor carpi ulnaris Flexor pollicis longus Palmaris longus tendon Radial a. Flexor digitorum superficialis A Ulnar tunnel and deep palm. Superficial palmar arch Median n., recurrent br. Flexor pollicis brevis, superficial head Flexor digiti minimi brevis Abductor pollicis brevis Abductor digiti minimi Opponens pollicis Superficial br. Flexor retinaculum (transverse carpal lig.) Ulnar n. Deep br. Ulnar a., deep br. Radial a., superficial palmar br. Median n. Ulnar a. and n. Flexor carpi radialis Flexor pollicis longus Flexor digitorum superficialis Flexor carpi ulnaris Carpal tunnel with flexor retinaculum B transparent. Removed: palmaris brevis, palmaris longus, palmar aponeurosis, and palmar carpal ligament. 390 Radial a. Extensor carpi radialis longus and brevis Fig. 28.40 Ulnar tunnel Right hand, anterior (palmar) view. Palmar aponeurosis Hook of hamate Ulnar a. and n., superficial brs. Hypothenar muscles Ulnar a. and n., deep brs. Deep palmar arch Superficial palmar arch Ulnar n. A Bony landmarks. Superficial br. Deep br. Hook of hamate Ulnar a. and n. Ulnar tunnel (proximal hiatus) Ulnar tunnel (distal hiatus) Palmar carpal lig. Pisiform Pisiform Flexor carpi ulnaris Radial a. Ulnar a. and n. 28 Neurovasculature Palmaris brevis Palmaris longus Flexor digitorum superficialis tendons B Apertures and walls of the ulnar tunnel. Fig. 28.41 Carpal tunnel: Cross section Right hand, proximal view. The tight fit of sensitive neurovascular structures with closely apposed, frequently moving tendons in the carpal tunnel often causes problems (carpal tunnel syndrome) when any of the structures swell or degenerate. Scaphoid Median n. Trapezium Thenar eminence Flexor retinaculum (transverse carpal lig.) Abductor pollicis longus tendon Ulnar a. and n. Pisiform Extensor pollicis brevis tendon Extensor pollicis longus tendon Close-up in B Hypothenar eminence Radial n., superficial br. Triquetrum Extensor carpi radialis longus tendon Extensor carpi ulnaris tendon Extensor digiti minimi tendon A Cross section through the right wrist. Extensor carpi radialis brevis tendon Hamate Extensor digitorum and extensor indicis tendons Capitate Flexor retinaculum (transverse carpal lig.) Flexor digitorum superficialis tendons Superficial palmar a. and v. Flexor carpi radialis tendon Palmar carpal lig. Ulnar a. and n. Median n. Pisiform Flexor pollicis longus tendon Synovial cavity Scaphoid Triquetrum B Structures in the ulnar tunnel (green) and carpal tunnel (blue). Hamate Capitate Flexor digitorum profundus tendons 391 Upper Limb Palm of the Hand Fig. 28.42 Superficial neurovascular structures of the palm Right hand, anterior view. Palmar digital nn. (exclusive area of median n.) Palmar digital n. (exclusive area of ulnar n.) Median n., palmar br. Palmar digital aa. Palmar digital nn. Ulnar n., palmar br. Radial n., dorsal digital n. Common palmar digital aa. A Sensory territories. Extensive overlap exists between adjacent areas. Exclusive nerve territories indicated with darker shading. Palmar digital nn. of thumb Flexor digiti minimi brevis Adductor pollicis Abductor digiti minimi Flexor pollicis brevis, superficial head Palmar aponeurosis Abductor pollicis brevis Palmaris brevis Flexor retinaculum (transverse carpal lig.) Radial a., superficial palmar br. Radial a. Ulnar a. and n. Palmaris longus tendon Ulnar tunnel B Superficial arteries and nerves. Antebrachial fascia Fig. 28.43 Neurovasculature of the finger Right middle finger, lateral view. Palmar digital n., dorsal branch Metacarpophalangeal joint Dorsal digital a. and n. Palmar digital a. Digitopalmar branches Metacarpal Palmar digital n. Proper palmar Common palmar digital a. and n. digital a. Nerves and arteries. A 392 Vincula brevia Vincula longa Blood supply to the flexor B tendons in the tendon sheath. Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Fig. 28.44 Deep neurovascular structures of the palm Fig. 28.45 Innervation patterns in the palm Right hand, anterior view. Median communicating br. Ulnar communicating br. Palmar digital aa. and nn. 28 Neurovasculature Right hand, anterior view. Palmar digital nn. B Median and ulnar communicating brs. (20%). 1st dorsal interosseous Lumbricals Common palmar digital aa. Adductor pollicis Flexor pollicis brevis, superficial head Superficial palmar arch Flexor digiti minimi brevis Abductor digiti minimi Ulnar n., superficial br. Radial a., superficial palmar br. Abductor pollicis brevis Opponens pollicis Ulnar a. and n., deep brs. A Ulnar communicating br. (45% of cases). Flexor retinaculum Palmaris longus Palmar carpal lig. Radial a., superficial palmar br. Median n. Ulnar a. and n. Flexor digitorum superficialis Pronator quadratus Radial a. Flexor carpi ulnaris Flexor pollicis longus Flexor carpi radialis Brachioradialis C No communicating brs. (20%). Palmar digital nn. Palmar digital aa. Common palmar digital aa. A Superficial palmar arch. Lumbricals Abductor digiti minimi Adductor pollicis, transverse head Flexor digiti minimi brevis Palmar metacarpal aa. Abductor pollicis brevis Flexor pollicis brevis Adductor pollicis, oblique head Deep palmar arch Opponens digiti minimi Superficial palmar arch Ulnar n., deep br. Ulnar n., superficial br. Opponens pollicis Radial a., superficial palmar br. Ulnar a., deep br. Ulnar a. and n. Pronator quadratus Flexor carpi ulnaris Sensitive terminal br. of the anterior interosseous n. Radial a. Anterior interosseous a. B Deep palmar arch. 393 Upper Limb Dorsum of the Hand Fig. 28.46 Cutaneous innervation of the dorsum of the hand Right hand, posterior view. Palmar digital nn., dorsal brs. (median n.) Dorsal digital nn. (radial n.) Median n., dorsal brs. of palmar digital nn. Exclusive area of median n. Dorsal digital n. (exclusive area of ulnar n.) Dorsal digital nn. (ulnar n.) Ulnar n., dorsal br. Radial n., superficial br. and dorsal digital nn. Ulnar n., dorsal br. Radial n., superficial br. Posterior antebrachial cutaneous n. (radial n.) A Nerves of the dorsum. B Sensory territories. Extensive overlap exists between adjacent areas. Exclusive nerve territories indicated with darker shading. Fig. 28.47 Anatomic snuffbox Right hand, radial view. The three-sided “anatomic snuffbox” (shaded green) is bounded by the tendons of insertion of the abductor pollicis longus and extensors pollicis brevis and longus. Extensor carpi radialis longus Extensor digitorum and extensor indicis tendons Trapezium Extensor carpi radialis brevis tendon Extensor pollicis longus tendon Extensor retinaculum Radial n., superficial br. 1st dorsal interosseous Scaphoid Radial a. 1st metacarpal 394 Extensor pollicis brevis tendon Abductor pollicis longus tendon Radial a. Fig. 28.48 Neurovascular structures of the dorsum 28 Neurovasculature Dorsal digital aa. Dorsal interossei Extensor pollicis longus tendon Dorsal metacarpal aa. Extensor digitorum tendon Extensor pollicis brevis tendon Extensor carpi radialis brevis and longus tendons Radial a. Dorsal carpal network A Superficial structures. Radial a., dorsal carpal br. Extensor digiti minimi tendon Ulnar a., dorsal carpal br. Extensor retinaculum Extensor carpi ulnaris tendon Dorsal digital aa. Extensor pollicis longus tendon Dorsal metacarpal aa. Extensor carpi radialis brevis tendon Radial a. Extensor carpi radialis longus tendon Dorsal carpal a. (radial a.) Extensor retinaculum Ulnar a., dorsal carpal br. Dorsal carpal network B Deep structures. 395 29 Sectional & Radiographic Anatomy Upper Limb Sectional Anatomy of the Upper Limb Fig. 29.1 Windowed dissection of the arm and forearm Right limb, anterior view. Biceps brachii Deltoid Brachialis Medial epicondyle, common head of flexors Biceps brachii, tendon of insertion Pectoralis major Bicipital aponeurosis Brachioradialis Extensor carpi radialis longus Coracobrachialis Teres major Extensor carpi radialis brevis Biceps brachii, long head Radius Pronator teres Flexor carpi radialis Palmaris longus Ulna Biceps brachii, short head Flexor carpi ulnaris Flexor digitorum superficialis Humerus Flexor pollicis longus Abductor pollicis longus Biceps brachii Thenar muscles Flexor retinaculum (transverse carpal ligament) Brachialis Brachioradialis Palmaris brevis Medial epicondyle A Dissection of the arm. 396 Palmaris longus Palmar aponeurosis B Right forearm Right limb, proximal view. Posterior Triceps brachii, lateral head Triceps brachii, long head Triceps brachii, medial head Radial nerve Lateral intermuscular septum of the arm Medial intermuscular septum of the arm Humerus Ulnar nerve Brachialis Brachial vein 29 Sectional & Radiographic Anatomy Fig. 29.2 Cross-section through the arm and forearm Brachial artery Median nerve Musculocutaneous nerve Biceps brachii, long head Biceps brachii, short head Anterior A Arm (plane of section in Fig. 29.1A) Posterior (dorsal) Posterior Extensor interosseous nerve pollicis brevis Interosseous of forearm membrane Extensor of forearm digiti minimi Extensor carpi ulnaris Extensor pollicis longus Abductor pollicis longus Extensor digitorum Ulna Flexor digitorum profundus Radius Extensor carpi radialis longus Ulnar nerve Anterior interosseous nerve of forearm Ulnar artery Extensor carpi radialis brevis Flexor carpi ulnaris Brachioradialis Flexor digitorum superficialis Radial nerve (superficial branch) Anterior (palmar) Pronator teres Radial artery Flexor pollicis longus Flexor carpi radialis Palmaris longus Median nerve B Forearm (plane of section in Fig. 29.1B) 397 Upper Limb Radiographic Anatomy of the Upper Limb (I) Fig. 29.3 MRI of the arm Transverse section, distal (inferior) view. A Biceps brachii (short head, tendon) Pectoralis major Humerus Coracobrachialis Deltoid Axillary a. and v., brachial plexus B Anterior humeral circumflex a. and v. Axillary n. Subscapularis Posterior humeral circumflex a. and v. C Scapula Triceps brachii (long head) Teres minor A Proximal arm. (Reproduced from Moeller TB, Reif E. Pocket Circumflex scapular a. and v. Atlas of ­Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Infraspinatus Cephalic v. Biceps brachii, long head Biceps brachii, short head Musculocutaneous n. Brachialis Humerus (shaft) Radial n. Triceps brachii, lateral head Mid-arm. (Reproduced B from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Deep brachial a. and v. Median n. Brachial a. and v. Basilic v. Ulnar n. Triceps brachii, medial head Triceps brachii, long head Cephaic v. Biceps brachii (long and short heads) Musculocutaneous n. Brachioradialis Radial n., deep brachial a. and v. Brachial a. and v. Median n. Brachialis Basilic v. Triceps brachii C Distal arm. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) 398 Humerus (shaft) Ulnar n., a. and v. Fig. 29.4 MRI of the forearm Transverse section, distal view. Brachioradialis Median n. Pronator teres Radial n. Brachialis Extensor carpi radialis brevis B Flexor digitorum superficialis Head of radius C Ulnar n. Anular lig. Flexor carpi ulnaris A Proximal forearm. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Ulna Proximal radioulnar joint Anconeus Flexor digitorum profundus Flexor carpi radialis 29 Sectional & Radiographic Anatomy Brachial a. and v. Median cubital v. A Flexor digitorum superficialis Median n. Ulnar a.,v., and n. Radial a. and vv. Flexor carpi ulnaris Brachioradialis (tendon) Flexor digitorum profundus Anterior interosseous a., v., and n. Ulna Cephalic v. Basilic v. Flexor pollicis longus B Mid-forearm. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Interosseous membrane Extensor carpi radialis brevis Extensor pollicis longus Radius Extensor indicis Abductor pollicis longus Extensor digitorum Extensor carpi radialis brevis (tendon) Extensor carpi radialis longus (tendon) Radius Radial a. and vv. C Distal forearm. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Flexor carpi radialis Extensor carpi ulnaris Extensor digitorum Extensor carpi ulnaris Ulna Pronator quadratus Flexor digitorum profundus Ulnar n. Ulnar a. and vv. Median n. Flexor digitorum superficialis Flexor carpi ulnaris 399 Radiographic Anatomy of the Upper Limb (II) Upper Limb Fig. 29.5 Radiograph of the right shoulder Anteroposterior view. Head of humerus Glenoid cavity Fig. 29.6 Radiograph of the scapula Infraglenoid tubercle Anteroposterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Acromioclavicular joint Clavicle Acromion Coracoid process Greater tubercle Lesser tubercle Superior angle Humerus, head Articular surface Scapular spine Scapula, neck Scapula, lateral margin Scapula, medial margin Scapula, inferior angle Fig. 29.7 Diagnostic ultrasound of the anterior region of the left shoulder Transverse section at the level of the intertubercular groove. (Reproduced from Konerman W, Gruber G. Ultraschalldiagnostik der Bewegungsorgane, 2nd ed. Stuttgart: Thieme; 2006.) Subscapularis tendon Lesser tubercle Tendon of biceps brachii, long head Deltoid Tendon of biceps brachii, long head Greater tubercle Lesser tubercle Greater tubercle A Sonogram. 400 Deltoid B Schematic of the transverse section. Fig. 29.8 MRI of the right shoulder joint in three planes Acromion Acromioclavicular joint Trapezius Tendon of supraspinatus Supraspinatus Head of humerus Suprascapular a., v., and n. Deltoid Glenoid cavity Biceps brachii, long head Subscapularis Axillary n., posterior humeral circumflex a. and v. Intercostal mm. Latissimus dorsi Serratus anterior A Coronal section, anterior view. Subacromial bursa 29 Sectional & Radiographic Anatomy Subacromial bursa Acromion Deltoid, clavicular part Supraspinatus Head of humerus Infraspinatus Teres minor Subscapularis Axillary n. Posterior humeral circumflex a. and v. Pectoralis major Teres major Deltoid, scapular part Biceps brachii, short head Biceps brachii, long head B Sagittal section, lateral view. Lesser tubercle Tendon of biceps brachii, long head Deltoid, acromial part Greater tubercle Head of humerus Glenoid cavity Deltoid, scapular part C Transverse section, inferior view. Subscapular a., v., and n. Deltoid, clavicular part Glenoid labrum Pectoralis minor Pectoralis major Subclavius Axillary a. and v. Brachial plexus Serratus anterior Subscapularis Scapula Infraspinatus 401 Upper Limb Radiographic Anatomy of the Upper Limb (III) Fig. 29.9 Radiograph of the elbow Anteroposterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Humerus Olecranon fossa Medial epicondyle Lateral epicondyle Olecranon Capitulum Trochlea Humeroradial joint Humeroulnar joint Radial head Coronoid process Radial tuberosity Proximal radioulnar joint Fig. 29.10 Radiograph of the elbow Lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Humerus Coronoid fossa Coronoid process Radial head Olecranon fossa Radial tuberosity Lateral epicondyle Humeroradial joint Radius Humeroulnar joint Olecranon 402 Ulna Fig. 29.11 MRI of the elbow Triceps brachii Humerus Brachialis Posterior fat body of elbow Anterior fat body and coronoid fossa Olecranon Humerus, trochlea Biceps brachii, tendon Coronoid process Brachioradialis Ulnar a. and v. Radial a. and v. Pronator teres A Sagittal section through the humeroulnar joint. Flexor digitorum profundus Radial n. Median n. 29 Sectional & Radiographic Anatomy (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Biceps brachii Brachialis Trochlear notch Humerus, capitulum Radial n. Radial head Humeroradial joint Proximal radioulnar joint Biceps brachii, tendon B Sagittal section through the humeroulnar and humeroradial joints. Radial tuberosity Supinator Flexor digitorum profundus Flexor digitorum superficialis Pronator teres, ulnar head Brachioradialis Brachioradialis Brachialis Extensor carpi radialis longus Lateral epicondyle Pronator teres Humeroradial joint Medial collateral lig. Radial head Supinator Radial tuberosity C Coronal section through the humeroulnar and humeroradial joints. Medial epicondyle Extensor digitorum Humeroulnar joint Ulna, coronoid process Brachialis Flexor carpi radialis 403 Upper Limb Radiographic Anatomy of the Upper Limb (IV) Fig. 29.12 Radiograph of the hand (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Distal phalanx Distal interphalangeal joint Head of proximal phalanx Proximal interphalangeal joint Middle phalanx Metacarpophalangeal joint Base of proximal phalanx Proximal phalanx Metacarpal Metacarpal head Metacarpal base Metacarpal base Trapezoid Capitate Scaphoid Triquetrum Radius, styloid process Lunate Radius, styloid process Pisiform Lunate Triquetrum Trapezium Hamate Trapezium Scaphoid Capitate and hamate Trapezoid Ulna, styloid process Ulna, styloid process A Anteroposterior view. B Oblique view. Fig. 29.13 MRI of the right wrist Transverse section, distal view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Dorsal Hamate Capitate Trapezoid Flexor digitorum profundus, tendon Radial a. and vv. Ulnar n., deep branch Flexor digitorum superficialis, tendon Trapezium Ulnar n. Flexor carpi radialis, tendon Ulnar a. and vv. Abductor pollicis longus, tendon 404 Median n. Flexor retinaculum Fig. 29.14 MRI of the hand Adductor pollicis Opponens digiti minimi Flexor pollicis brevis, deep head Flexor digiti minimi Abductor pollicis Abductor digiti minimi Opponens pollicis Flexor pollicis longus, tendon Hamate, hook Metacarpal I, base Pisiform Trapezium Palmar radiocarpal lig. Scaphoid 29 Sectional & Radiographic Anatomy (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Flexor digitorum profundus, tendons A Coronal section through the carpal tunnel. Dorsal digital aa. and nn. Collateral lig. Metacarpophalangeal joint Proximal phalanx, base Interosseous muscles Metacarpal, head Carpometacarpal joint Metacarpal II, base Trapezoid Hamate Capitate Scaphoid Ulna Radius B Coronal section through the palm. Metacarpal II-IV, shafts Extensor digitorum, tendons Dorsal Dorsal (extensor) expansion Dorsal interosseous mm. Palmar interosseous mm. Collateral lig. Metacarpal V, head Lumbricals Palmar digital aa. and nn. First proximal phalanx C Transverse section through the palm, distal view. Flexor pollicis longus, tendon Flexor digitorum superficialis, tendon Flexor digitorum profundus, tendon 405 Lower Limb 30 Surface Anatomy 34 Neurovasculature Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408 31 Hip & Thigh Bones of the Lower Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . . Femur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hip Joint: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hip Joint: Ligaments & Capsule . . . . . . . . . . . . . . . . . . . . . . . Anterior Muscles of the Hip, Thigh & Gluteal Region (I) . . . . Anterior Muscles of the Hip, Thigh & Gluteal Region (II) . . . Posterior Muscles of the Hip, Thigh & Gluteal Region (I) . . . Posterior Muscles of the Hip, Thigh & Gluteal Region (II) . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 412 414 416 418 420 422 424 426 428 430 32 Knee & Leg Tibia & Fibula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint: Capsule, Ligaments & Bursae . . . . . . . . . . . . . . . Knee Joint: Ligaments & Menisci . . . . . . . . . . . . . . . . . . . . . . Cruciate Ligaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Knee Joint Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscles of the Leg: Anterior & Lateral Compartments . . . . . Muscles of the Leg: Posterior Compartment . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432 434 436 438 440 442 444 446 448 450 33 Ankle & Foot Bones of the Foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Joints of the Foot (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligaments of the Ankle & Foot . . . . . . . . . . . . . . . . . . . . . . . . Plantar Vault & Arches of the Foot . . . . . . . . . . . . . . . . . . . . . Muscles of the Sole of the Foot . . . . . . . . . . . . . . . . . . . . . . . Muscles & Tendon Sheaths of the Foot . . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452 454 456 458 460 462 464 466 468 470 Arteries of the Lower Limb . . . . . . . . . . . . . . . . . . . . . . . . . . . Veins & Lymphatics of the Lower Limb . . . . . . . . . . . . . . . . . Lumbosacral Plexus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nerves of the Lumbar Plexus . . . . . . . . . . . . . . . . . . . . . . . . . Nerves of the Lumbar Plexus: Obturator & Femoral Nerves . . Nerves of the Sacral Plexus . . . . . . . . . . . . . . . . . . . . . . . . . . . Nerves of the Sacral Plexus: Sciatic Nerve . . . . . . . . . . . . . . . Superficial Nerves & Veins of the Lower Limb . . . . . . . . . . . . Topography of the Inguinal Region . . . . . . . . . . . . . . . . . . . . Topography of the Gluteal Region . . . . . . . . . . . . . . . . . . . . . Topography of the Anterior, Medial & Posterior Thigh . . . . . Topography of the Posterior Compartment of the Leg & Foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Lateral & Anterior Compartments of the Leg & Dorsum of the Foot . . . . . . . . . . . . . . . . . . . . Topography of the Sole of the Foot . . . . . . . . . . . . . . . . . . . . 472 474 476 478 480 482 484 486 488 490 492 494 496 498 35 Sectional & Radiographic Anatomy Sectional Anatomy of the Lower Limb . . . . . . . . . . . . . . . . . . Radiographic Anatomy of the Lower Limb (I) . . . . . . . . . . . . Radiographic Anatomy of the Lower Limb (II) . . . . . . . . . . . . Radiographic Anatomy of the Lower Limb (III). . . . . . . . . . . . Radiographic Anatomy of the Lower Limb (IV). . . . . . . . . . . . 500 502 504 506 508 30 Surface Anatomy Lower Limb Surface Anatomy Fig. 30.1 Palpable bony prominences of the lower limb Right limb. Iliac crest Anterior superior iliac spine Greater trochanter Iliac crest Posterior superior iliac spine Pubic tubercle Sacrum Pubic symphysis Ischial tuberosity Fig. 30.2 Regions of the lower limb Right leg. Patella Lateral tibial condyle Medial tibial condyle Medial epicondyle Lateral epicondyle Head of fibula Tibial tuberosity Anterior thigh region Medial surface of tibia Lateral malleolus Tuberosity of 5th metatarsal Anterior genual region Medial malleolus Navicular tuberosity Metatarsophalangeal joints Navicular tuberosity Calcaneal tuberosity Tuberosity of 5th metatarsal Posterior leg region Interphalangeal joints of the foot A Anterior view. Femoral trigone B Posterior view. Anterior leg region Dorsum of the foot A Anterior view. 408 Iliac crest Tensor fascia lata Gluteus maximus Gluteus medius Rectus femoris 30 Surface Anatomy Fig. 30.3 Palpable musculature of the lower limb Iliotibial tract Sartorius Semimembranosus, semitendinosus Vastus medialis Vastus lateralis Biceps femoris Gluteal region Gastrocnemius Posterior thigh region Fibularis longus Gastrocnemius Tibialis anterior Tibia Calcaneal (Achilles’) tendon Popliteal region Posterior leg region Extensor hallucis longus A Anterior view, left limb. Extensor digitorum tendons B Posterior view, right limb. Lateral retromalleolar region Calcaneal region Sole of the foot B Posterior view. 409 31 Hip & Thigh Lower Limb Bones of the Lower Limb The skeleton of the lower limb consists of a coxal (hip) bone and a free limb. The paired coxal bones attach to the trunk at the sacroiliac joint to form the pelvic girdle (see p. 230), and the free limb, divided into a thigh, leg, and foot, attaches to the pelvic girdle at the hip joint. Stability of the pelvic girdle is important in the distribution of weight from the upper body to the lower limbs. Fig. 31.1 Bones of the lower limb Posterior superior iliac spine Coxal bone Iliac crest Coxal bone Iliac crest Pelvic girdle (right side) Coxal bone Anterior superior iliac spine Neck of femur Hip joint Ischial spine Pubic tubercle Greater trochanter Ischial tuberosity Lesser trochanter Thigh Lesser trochanter Femur Greater trochanter Femur Medial condyle Patella Patella Tibial plateau Head of fibula Lateral condyle Medial epicondyle Knee joint Lateral tibial condyle Knee joint Tibial tuberosity Medial tibial condyle Head of fibula Tibia Tibia Fibula Fibula Fibula Leg Medial malleolus Ankle mortise Talocrural (ankle) joint Lateral malleolus Lateral malleolus Calcaneus Tarsals Metatarsals Foot Tuberosity of 5th metatarsal Calcaneus Phalanges A Anterior view. 410 B Right lateral view. C Posterior view. Fig. 31.3 The coxal bones and their relation to the ­vertebral column. Right lateral view. The line of gravity runs vertically from the whole-body center of gravity to the ground with characteristic points of intersection. The paired coxal bones and sacrum form the pelvic girdle (see p. 230). 31 Hip & Thigh Fig. 31.2 Line of gravity L4 External auditory canal Dens of axis (C2) Sacroiliac joint Inflection points of vertebral column Sacrum Coxal bone Coccyx Hip joint Center of gravity Hip joint Pubic symphysis Knee joint A Anterior view. Ankle joint L4 Coxal bone Neck of femur Sacrum Greater trochanter Ischial tuberosity B Posterior view. 411 Lower Limb Femur Fig. 31.4 Femur Right femur. The femur articulates proximally with the acetabulum of the pelvis at the hip joint and distally with the tibia at the knee joint. Head Fovea Trochanteric fossa Neck Greater trochanter Greater trochanter Intertrochanteric crest Lesser trochanter Intertrochanteric line Pectineal line Gluteal tuberosity Shaft Lateral lip Medial lip Medial supracondylar line Lateral supracondylar line Adductor tubercle Popliteal surface Medial epicondyle Intercondylar line Lateral epicondyle Lateral epicondyle Lateral condyle Lateral condyle A Anterior view. 412 Linea aspera Patellar surface Medial condyle Intercondylar notch B Posterior view. Acetabular labrum Patella 31 Hip & Thigh Patellar surface of femur Acetabulum Head of femur Fovea of femoral head Fig. 31.5 Hip joint: Transverse section Neck of femur Right hip joint, superior view. Greater trochanter Medial condyle Iliopectineal bursa Lateral condyle C Proximal view. The acetabulum has been sectioned in the horizontal plane. Head of femur Patellar surface of femur (femoral trochlea) Fibrous membrane Lig. of head of femur Neck of femur Acetabulum Patellar surface of femur Lateral condyle Greater trochanter Trochanteric bursa Ischium Medial condyle Intercondylar notch DDistal view. Clinical box 31.1 Rotation of the femoral head The acetabular rim is oriented anteroinferiorly relative to the sagittal plane. At birth, the aperture angle measures approximately 7 degrees but increases to 17 degrees by adulthood (A). This angle affects the stability and “seating” of the femoral head in the hip joint. When the femoral head is centered in the 17° acetabulum, the distal femur and thus the knee joint, point slightly inward. Note how external (B) and internal (C) rotation of the femoral head affect the orientation of the knee joint. Acetabular inlet plane Sagittal (anterior) aperture angle Patella A Sagittal plane B C 413 Hip Joint: Overview Lower Limb Fig. 31.6 Right hip joint The head of the femur articulates with the acetabulum of the pelvis at the hip joint, a special type of spheroidal (ball-and-socket) joint. The roughly spherical femoral head (with an average radius of curvature of approximately 2.5 cm) is largely contained within the acetabulum. Iliac crest Anterior superior iliac spine Iliac crest Bony acetabular rim Head of femur Posterior superior iliac spine Greater trochanter Intertrochanteric line Pubic tubercle Neck of femur Lesser trochanter Posterior inferior iliac spine Acetabular rim Head of femur Greater trochanter Neck of femur Intertrochanteric crest A Anterior view. Lesser trochanter Ischial spine Gluteal tuberosity Ischial tuberosity Pectineal line Linea aspera B Posterior view. 414 31 Hip & Thigh Fig. 31.7 Hip joint: Coronal section Right hip joint, anterior view. Epiphyseal line Clinical box 31.2 Ilium Neck of femur Acetabulum Head of femur Lig. of head of femur Fractures of the femur Femoral fractures caused by falls in patients with osteoporosis are most frequently located in the neck of the femur. Femoral shaft fractures are less frequent and are usually caused by strong trauma (e.g., a car accident). Acetabular fossa Acetabular labrum Medial femoral neck fractures Lateral femoral neck fracture Peritrochanteric femoral fracture Greater trochanter Subtrochanteric femoral fracture Shaft of femur Trochanteric bursa Clinical box 31.3 Diagnosing hip dysplasia and dislocation Ultrasonography, the most important imaging method for screening the infant hip, is used to identify morphological changes such as hip dysplasia and dislocation. Clinically, hip dislocation presents with instability and limited abduction of the hip joint, and leg shortening with asymmetry of the gluteal folds. Ilium Bony acetabular rim Bony acetabular rim Acetabular labrum Acetabular labrum Ossification center Femur A Normal hip joint in a 5-month-old. Inferior margin of ilium Femur Inferior margin of ilium B Hip dislocation and dysplasia in a 3-month-old. 415 Lower Limb Hip Joint: Ligaments & Capsule The hip joint has three major ligaments: iliofemoral, pubofemoral, and ischiofemoral. The iliofemoral, the strongest of these, provides an important constraint for the hip joint: it prevents the pelvis from tilting posteriorly in the upright stance, without the need for muscular effort. It also limits adduction of the extended limb and stabilizes the pelvis on the stance side during gait. A fourth ligament, the zona orbicularis (anular ligament) is not visible externally and encircles the femoral neck like a buttonhole. Fig. 31.8 Ligaments of the hip joint Right hip joint. L5 vertebra Posterior superior iliac spine Iliac crest Anterior superior iliac spine Posterior sacroiliac ligs. Inguinal lig. Sacrum Pubofemoral lig. Sacrospinous lig. Pubic tubercle Ischial spine Iliofemoral lig. Sacrotuberous lig. Greater trochanter Ischiofemoral lig. A Lateral view Femur Iliolumbar lig. Iliolumbar lig. Iliac crest L5 vertebra Anterior sacroiliac ligs. Posterior sacroiliac ligs. Sacrotuberous lig. Ischial spine Sacrospinous lig. Iliofemoral lig. Ischial spine Greater trochanter 416 Iliac crest Sacral promontory Inguinal lig. B Anterior view L4 vertebra Anterior longitudinal lig. L5 vertebra Anterior superior iliac spine Intertrochanteric line L4 vertebra Pubic symphysis Lesser trochanter Posterior superior iliac spine Iliofemoral lig. Greater trochanter Sacrospinous lig. Intertrochanteric crest Sacrotuberous lig. Lesser trochanter Ischial tuberosity Pubofemoral lig. C Posterior view Ischiofemoral lig. Fig. 31.9 Weakness in the joint capsule A Anterior view 31 Hip & Thigh Right hip joint. Weak spots in the joint capsule (color-shaded areas) are located between the joint ligaments. External trauma may cause the femoral head to dislocate from the acetabulum at these sites. Iliofemoral lig. Iliofemoral lig. Pubofemoral lig. B Posterior view Ischiofemoral lig. Fig 31.10 Synovial membrane of the joint capsule Synovial membrane Fibrous membrane Reflection of synovial membrane Neck of femur Greater trochanter Intertrochanteric line Synovial membrane Fibrous membrane Lesser trochanter A Anterior view B Posterior view Fig. 31.11 Ligament of the head of the femur in the acetabulum Right hip joint, lateral view. Acetabular labrum Acetabular roof Joint capsule Acetabular fossa Obturator membrane Acetabular labrum Lunate surface Fovea on femoral head Lig. of head of femur Greater trochanter Lig. of head of femur A The joint capsule has been divided and the femoral head dislocated to expose the cut ligament of the head of the femur. Lesser trochanter Joint capsule Acetabular fossa Transverse lig. of acetabulum B Acetabulum of the hip joint. Note: The ligament of the head of the femur (cut) has no mechanical function, but transmits branches from the obturator artery that nourish the femoral head (see p. 473). 417 Lower Limb Anterior Muscles of the Hip, Thigh & Gluteal Region (I) Fig. 31.12 Anterior muscles of the hip and thigh (I) Right limb. Muscle origins are shown in red, insertions in blue. Anterior longitudinal lig. Iliac crest Iliacus Sacral promontory Anterior superior iliac spine Psoas major Piriformis Sartorius Inguinal lig. Rectus femoris Tensor fasciae latae Iliopsoas Pubic symphysis Pectineus Adductor longus Rectus femoris Sartorius Gracilis Vastus intermedius Adductor magnus Iliotibial tract Vastus medialis Vastus lateralis Sartorius Quadriceps femoris tendon Gracilis Patella Head of fibula Patellar lig. Semitendinosus Pes anserinus A Removed: Fascia lata of thigh (to the lateral iliotibial tract). 418 Pes anserinus (common tendon of insertion) B Removed: Inguinal ligament, sartorius and rectus femoris. Iliacus 31 Hip & Thigh Psoas major Psoas major Iliacus Sartorius Sartorius Tensor fasciae latae Gluteus medius Piriformis Rectus femoris Gluteus minimus Piriformis Piriformis Rectus femoris Gluteus minimus Piriformis Iliofemoral lig. Obturator externus Iliopsoas Pectineus Vastus lateralis Vastus medialis Gluteus medius Pectineus Obturator externus Vastus lateralis Adductor brevis Iliopsoas Adductor minimus Adductor brevis Vastus medialis Adductor longus Adductor longus Gracilis Gracilis Vastus intermedius Vastus intermedius Adductor magnus Adductor magnus Adductor hiatus Vastus lateralis Articularis genus Adductor hiatus Articularis genus Vastus medialis Iliotibial tract Iliotibial tract Patellar lig. Pes anserinus C Removed: Rectus femoris (completely), vastus lateralis, vastus ­medialis, iliopsoas, and tensor fasciae latae. Biceps femoris Quadriceps femoris Semimembranosus Gracilis Sartorius Semitendinosus Pes anserinus (common tendon of insertion) DRemoved: Quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), iliopsoas, tensor fasciae latae, pectineus, and midportion of adductor longus. 419 Lower Limb Anterior Muscles of the Hip, Thigh & Gluteal Region (II) Fig. 31.13 Anterior muscles of the hip and thigh (II) Right limb. Muscle origins are shown in red, insertions in blue. Psoas major Iliacus Sartorius Rectus femoris Piriformis Pectineus Piriformis Obturator externus Gluteus minimus Vastus lateralis Gracilis Iliopsoas Adductor longus Adductor minimus Adductor brevis Quadratus femoris Adductor magnus Adductor hiatus Piriformis Rectus femoris Piriformis Pectineus Gluteus minimus Gracilis Adductor longus Vastus lateralis Adductor brevis Iliopsoas Quadratus femoris Vastus medialis Adductor magnus Obturator externus Vastus intermedius Articularis genus Tendinous insertion of adductor magnus Adductor magnus Adductor tubercle Semimembranosus Iliotibial tract Semimembranosus Gracilis Biceps femoris Gracilis Sartorius Quadriceps femoris A Removed: Gluteus medius and minimus, piriformis, obturator externus, adductor brevis and longus, and gracilis. 420 Semitendinosus B Removed: All muscles. Midsagittal section. L5 vertebral body Iliac crest 31 Hip & Thigh Fig. 31.14 Medial muscles of the hip, thigh, and gluteal region Sacral promontory Iliacus Anterior superior iliac spine Sacrum Psoas minor Psoas major Obturator internus Piriformis Sacrospinous lig. Pubic symphysis Gluteus maximus Sartorius Adductor magnus Adductor longus Rectus femoris Semitendinosus Gracilis Semimembranosus Vastus medialis Patella Patellar lig. Pes anserinus (common tendon of insertion) Gastrocnemius Tibialis anterior Tibia 421 Posterior Muscles of the Hip, Thigh & Gluteal Region (I) Lower Limb Fig. 31.15 Posterior muscles of the hip, thigh, and gluteal region (I) Right limb. Muscle origins are shown in red, insertions in blue. L5 spinous process Gluteus medius Iliac crest Iliac crest Anterior superior iliac spine Anterior superior iliac spine Gluteus medius Tensor fasciae latae Gluteus maximus Greater trochanter Gluteus minimus Gluteus maximus Tensor fasciae latae Gemellus superior Piriformis Gluteus medius Gemellus inferior Obturator internus Quadratus femoris Gluteus maximus Sacrotuberous lig. Adductor magnus Ischial tuberosity Adductor magnus Semitendinosus Iliotibial tract Biceps femoris, long head Gracilis Semimembranosus Iliotibial tract Semitendinosus Gracilis Popliteal fossa Semimembranosus Plantaris Plantaris Pes anserinus Gastrocnemius, medial and lateral heads A Removed: Fascia lata (to iliotibial tract). 422 Biceps femoris, long head Gastrocnemius, medial and lateral heads B Partially removed: Gluteus maximus and medius. Tensor fasciae latae Tensor fasciae latae Gluteus minimus Gluteus maximus Gemellus superior Piriformis Gemellus inferior Gluteus medius Obturator internus Quadratus femoris Sacrotuberous lig. Vastus lateralis Adductor magnus Gluteus maximus Gluteus minimus Gluteus maximus Gemellus superior Rectus femoris Gemellus inferior Piriformis Gluteus medius and minimus Obturator internus Quadratus femoris Semimembranosus Biceps femoris (long head) and semitendinosus (cut) Gluteus maximus Adductor magnus Adductor magnus Vastus intermedius Vastus intermedius Semimembranosus Semitendinosus (cut) Gracilis 31 Hip & Thigh Gluteus medius Gluteus medius Biceps femoris, short head Biceps femoris, long head Vastus lateralis Adductor hiatus Biceps femoris, short head Plantaris Plantaris Gastrocnemius, medial and lateral heads Semimembranosus Biceps femoris Popliteus Soleus Gastrocnemius, medial and lateral heads Tibialis posterior Flexor digitorum longus C Removed: Semitendinosus and biceps femoris (partially); gluteus maximus and medius (completely). DRemoved: Hamstrings (semitendinosus, semimembranosus, and biceps femoris), gluteus minimus, gastrocnemius, and muscles of the leg. 423 Lower Limb Posterior Muscles of the Hip, Thigh & Gluteal Region (II) Fig. 31.16 Posterior muscles of the hip, thigh, and gluteal region (II) Right limb. Muscle origins are shown in red, insertions in blue. Gluteus medius Tensor fasciae latae Gluteus minimus Gluteus maximus Gemellus superior Obturator externus Gemellus inferior Gluteus medius and minimus, piriformis Obturator internus Quadratus femoris Iliopsoas Rectus femoris Obturator internus and externus, gemellus superior and inferior Gemellus superior Gemellus inferior Gluteus medius and minimus, piriformis Obturator internus Quadratus femoris Semimembranosus Biceps femoris, long head and semitendinosus Iliopsoas Adductor magnus Adductor magnus Gluteus maximus Pectineus Vastus lateralis Adductor brevis Adductor brevis Vastus medialis Adductor longus Adductor magnus Vastus intermedius Adductor magnus Adductor longus Biceps femoris, short head Vastus medialis Adductor magnus Adductor magnus Plantaris Gastrocnemius, medial and lateral heads Semimembranosus Biceps femoris Popliteus Soleus Tibialis posterior Flexor digitorum longus A Removed: Piriformis, obturator internus, quadratus femoris, and adductor magnus. 424 B Removed: All muscles. 31 Hip & Thigh Fig. 31.17 Lateral muscles of the hip, thigh, and gluteal region Note: The iliotibial tract (the thickened band of fascia lata) functions as a tension band to reduce the bending loads on the proximal femur. L4 spinous process Posterior superior iliac spine Iliac crest Anterior superior iliac spine Gluteus medius Tensor fasciae latae Gluteus maximus Sartorius Rectus femoris Iliotibial tract Long head Biceps femoris Short head Vastus lateralis Patella Fibula, head Fibularis longus Gastrocnemius Patellar lig. Tibial tuberosity Tibialis anterior 425 Lower Limb Muscle Facts (I) Iliopsoas muscle Table 31.1 Muscles Origin Insertion ① Psoas major* Superficial: T12–L4 and associated intervertebral disks (lateral surfaces) Deep: L1–L5 vertebrae (costal processes) ② Iliacus Iliac fossa ③ Iliopsoas Femur (lesser trochanter) Innervation Action Lumbar plexus L1, L2(L3) Femoral n. (L2–L3) • Hip joint: flexion and external rotation • Lumbar spine: unilateral contraction (with the femur fixed) flexes the trunk laterally to the same side; bilateral contraction raises the trunk from the supine position * The psoas minor, present in approximately 50% of the population, is often found on the superficial surface of the psoas major (see Fig. 31.19). It is not a muscle of the lower limb. It originates, inserts, and exerts its action on the abdomen (see Table 13.1, p. 148). Fig. 31.18 Muscles of the hip Right side, schematic. G F K SA H J Ö Iliotibial tract L Ä D A Iliopsoas muscle, anterior view. Table 31.2 426 B Vertically oriented gluteal muscles, posterior view. C Horizontally oriented gluteal muscles, posterior view. Gluteal muscles Muscle Origin Insertion Innervation Action ④ Gluteus maximus Sacrum (dorsal surface, lateral part), ilium (gluteal surface, posterior part), thoracolumbar fascia, sacrotuberous lig. • Upper fibers: iliotibial tract • Lower fibers: gluteal tuberosity Inferior gluteal n. (L5–S2) • Entire muscle: extends and externally rotates the hip in sagittal and coronal planes • Upper fibers: abduction • Lower fibers: adduction ⑤ Gluteus medius Ilium (gluteal surface below the iliac crest between the anterior and posterior gluteal line) Greater trochanter of the femur (lateral surface) ⑥ Gluteus minimus Ilium (gluteal surface below the origin of gluteus medius) Greater trochanter of the femur (anterolateral surface) ⑦ Tensor fasciae latae Anterior superior iliac spine Iliotibial tract ⑧ Piriformis Pelvic surface of the sacrum Apex of the greater trochanter of the femur ⑨ Obturator internus Inner surface of the obturator membrane and its bony boundaries Medial surface of the greater trochanter ⑩ Gemelli • Gemellus superior: ischial spine • Gemellus inferior: ischial tuberosity Jointly with obturator internus tendon (medial surface, greater trochanter) ⑪ Quadratus femoris Lateral border of the ischial tuberosity Intertrochanteric crest of the femur Superior gluteal n. (L4–S1) • Entire muscle: abducts the hip, stabilizes the pelvis in the coronal plane • Anterior part: flexion and internal rotation • Posterior part: extension and external rotation • Tenses the fascia lata • Hip joint: abduction, flexion, and internal rotation Sacral plexus (S1, S2) Sacral plexus (L5, S1) • External rotation, abduction, and extension of the hip joint • Stabilizes the hip joint External rotation and extension of the hip joint (also active in abduction, depending on the joint’s position) External rotation of the hip joint Fig. 31.19 Psoas and iliacus muscles Fig. 31.20 Superficial muscles of the gluteal region Right side, anterior view. Right side, posterior view. Gluteus medius Thoracolumbar fascia Tensor fasciae latae Gluteus maximus Psoas minor 31 Hip & Thigh Iliac crest Psoas major L5 vertebra Sacral promontory Axis of abduction/ adduction Iliac crest Iliotibial tract Iliacus Anterior superior iliac spine Inguinal lig. Sacrospinous lig. Greater trochanter Tibia Fibula Intertrochanteric line Interosseous membrane Iliopsoas Lesser trochanter Fig. 31.21 Deep muscles of the gluteal region Iliac crest Iliac crest Ilium, gluteal surface Anterior superior iliac spine Gluteus medius Posterior gluteal line Gluteus minimus Piriformis Piriformis Obturator internus Gemellus superior and inferior Quadratus femoris Obturator internus Gemellus superior and inferior Quadratus femoris Ischial spine Greater trochanter Greater trochanter Sacrotuberous lig. Ischial tuberosity A Deep layer with gluteus maximus removed. Gluteal tuberosity Lesser trochanter Intertrochanteric crest B Deep layer with gluteus maximus and gluteus medius removed. 427 Lower Limb Muscle Facts (II) Functionally, the medial thigh muscles are considered the adductors of the hip. Promontory Iliac crest Fig. 31.22 Medial thigh muscles: Superficial layer Right side, anterior view. Superior pubic ramus Greater trochanter Lesser trochanter Pectineus A S D Adductor brevis Adductor longus Femur Gracilis F Patella A Schematic. Gracilis tendon Tibia B Superficial adductor group. Table 31.3 428 Fibula Medial thigh muscles: Superficial layer Muscle Origin Insertion Innervation Action ① Pectineus Pecten pubis Femur (pectineal line and the proximal linea aspera) Femoral n., obturator n. (L2, L3) • Hip joint: adduction, external rotation, and slight flexion • Stabilizes the pelvis in the coronal and sagittal planes ② Adductor longus Superior pubic ramus and anterior side of the pubic symphysis Obturator n. (L2–L4) ③ Adductor brevis Inferior pubic ramus • Hip joint: adduction and flexion (up to 70 degrees); extension (past 80 degrees of flexion) • Stabilizes the pelvis in the coronal and sagittal planes ④ Gracilis Inferior pubic ramus below the pubic symphysis Femur (linea aspera, medial lip in the middle third of the femur) Tibia (medial border of the tuberosity, along with the tendons of sartorius and semitendinosus) Obturator n. (L2, L3) • Hip joint: adduction and flexion • Knee joint: flexion and internal rotation Fig. 31.23 Medial thigh muscles: Deep layer Right side, anterior view. 31 Hip & Thigh Iliac crest Superior pubic ramus Obturator externus Greater trochanter A Lesser trochanter S Femur S Adductor magnus Adductor hiatus Adductor magnus, tendinous part Adductor tubercle Patella A Schematic. Tibial tuberosity Tibia Fibula B Deep adductor group. Table 31.4 Medial thigh muscles: Deep layer Muscle Origin Insertion Innervation Action ① Obturator externus Outer surface of the obturator membrane and its bony boundaries Trochanteric fossa of the femur Obturator n. (L3, L4) •H ip joint: adduction and external rotation •S tabilizes the pelvis in the sagittal plane • Deep part (“fleshy insertion”): medial lip of the linea aspera • Deep part: obturator n. (L2–L4) • Superficial part (“tendinous insertion”): adductor tubercle of the femur • Superficial part: tibial n. (L4) ② Adductor magnus Inferior pubic ramus, ischial ramus, and ischial tuberosity •H ip joint: adduction, extension, and slight flexion (the tendinous insertion is also active in internal rotation) •S tabilizes the pelvis in the coronal and sagittal planes 429 Lower Limb Muscle Facts (III) The anterior and posterior muscles of the thigh can be classified as extensors and flexors, respectively, with regard to the knee joint. Fig. 31.24 Anterior thigh muscles Right side, anterior view. Anterior superior iliac spine Sartorius Anterior inferior iliac spine Acetabular roof Greater trochanter Greater trochanter Intertrochanteric line S A Sartorius Rectus femoris G Vastus medialis Vastus lateralis Vastus medialis Quadriceps femoris tendon Rectus femoris Sartorius Patella Lateral patellar retinaculum Patellar lig. Pes anserinus Fibula Medial patellar retinaculum Tibial tuberosity A Schematic. B Superficial group. C Deep group. Removed: Sartorius and rectus femoris. Anterior thigh muscles Muscle Origin Insertion Innervation Action ① Sartorius Anterior superior iliac spine Medial to the tibial tuberosity (together with gracilis and semitendinosus) Femoral n. (L2, L3) • Hip joint: flexion, abduction, and external rotation • Knee joint: flexion and internal rotation ② Rectus femoris Anterior inferior iliac spine, acetabular roof of hip joint Tibial tuberosity (via patellar lig.) ③ Vastus medialis Linea aspera (medial lip), intertrochanteric line (distal part) ④ Vastus lateralis Linea aspera (lateral lip), greater trochanter (lateral surface) Tibial tuberosity via patellar lig.; patella and tibial tuberosity via respective medial and lateral patellar retinacula ⑤ Vastus intermedius Femoral shaft (anterior side) Tibial tuberosity (via patellar lig.) Articularis genus (distal fibers of vastus intermedius) Anterior side of femoral shaft at level of the suprapatellar recess Suprapatellar recess of knee joint capsule Quadriceps femoris* *The entire muscle inserts on the tibial tuberosity via the patellar lig. 430 Quadriceps femoris D F Table 31.5 Rectus femoris Vastus intermedius Vastus lateralis Lesser trochanter • Hip joint: flexion • Knee joint: extension Femoral n. (L2–L4) Knee joint: extension Knee joint: extension; retracts the suprapatellar bursa to prevent entrapment of capsule Right side, posterior view. Anterior superior iliac spine Posterior superior iliac spine Posterior inferior iliac spine Ischial spine Sacrotuberous lig. Ischial tuberosity Gluteal tuberosity Common head S D Biceps femoris, short head Semitendinosus Biceps femoris, long head Linea aspera Biceps femoris, short head Semitendinosus A Biceps femoris, long head Semimembranosus Popliteus A Schematic. Semimembranosus Semimembranosus tendon (part) Fibula, head Popliteus Pes anserinus Medial tibial condyle Popliteus Interosseous membrane B Superficial group. Table 31.6 31 Hip & Thigh Fig. 31.25 Posterior thigh muscles C Deep group. Removed: Biceps femoris (long head) and semitendinosus. Posterior thigh muscles Muscle Origin ① Biceps femoris Long head: ischial tuberosity, sacrotuberous lig. (common head with semitendinosus) Insertion Innervation Action Tibial n. (L5–S2) • Hip joint (long head): extends the hip, stabilizes the pelvis in the sagittal plane • Knee joint: flexion and external rotation Common fibular n. (L5–S2) Knee joint: flexion and external rotation Tibial n. (L5–S2) • Hip joint: extends the hip, stabilizes the pelvis in the sagittal plane • Knee joint: flexion and internal rotation Head of fibula Short head: lateral lip of the linea aspera in the middle third of the femur ② Semimembranosus Ischial tuberosity Medial tibial condyle, oblique popliteal lig., popliteus fascia ③ Semitendinosus Ischial tuberosity and sacrotuberous lig. (common head with long head of biceps femoris) Medial to the tibial tuberosity in the pes anserinus (along with the tendons of gracilis and sartorius) See p. 451 for the popliteus. 431 32 Knee & Leg Lower Limb Tibia & Fibula The tibia and fibula articulate at two joints, allowing limited motion (rotation). The crural interosseous membrane is a sheet of tough connective tissue that serves as an origin for several muscles in the leg. It also acts with the tibiofibular syndesmosis to stabilize the ankle joint. Fig. 32.1 Tibia and fibula Right leg. Lateral condyle Tibial plateau Tibial plateau Tibiofibular joint Medial condyle Head of fibula Tibiofibular joint Medial condyle Head of fibula Intercondylar eminence Neck of fibula Tibial tuberosity Neck of fibula Head of tibia Soleal line Interosseous membrane Interosseous membrane Fibula, shaft Medial surface Lateral surface Tibiofibular syndesmosis Lateral malleolus A Anterior view. 432 Lateral condyle Tibia, shaft Tibia, shaft Lateral surface Fibula, shaft Medial surface Posterior surface Anterior border Medial malleolus Ankle mortise Malleolar groove (for tibialis posterior tendon) Medial malleolus B Posterior view. Lateral malleolar fossa Lateral malleolus Clinical box 32.1 Head of fibula Fibular fracture Posterior intercondylar area When diagnosing a fibular fracture, it is important to determine whether the tibiofibular syndesmosis (see p. 432) is disrupted. Fibular fractures may occur distal to, level with, or proximal to the tibiofibular syndesmosis; the latter two frequently involve tearing of the syndesmosis. 32 Knee & Leg Intercondylar eminence Fibula Tibia Medial malleolus Tibiofibular syndesmosis Lateral malleolus Talus Calcaneus Lateral condyle Tibial tuberosity Medial condyle Anterior intercondylar area C Proximal view. Posterior surface Posterior surface Interosseous membrane Tibia Lateral surface Fibula In this fracture located proximal to the syndesmosis (arrow), the syndesmosis is torn, as indicated by the widened medial joint space of the upper ankle joint (see pp. 456–457). Medial surface Medial surface Lateral surface Anterior border DTransverse section, proximal view. Articular surface of lateral malleolus Inferior articular surface Articular surface of medial malleolus Fibula Lateral malleolus Medial malleolus Lateral malleolar fossa Tibia Distal view. E 433 Lower Limb Knee Joint: Overview In the knee joint, the femur articulates with the tibia and patella. Both joints are contained within a common capsule and have communicating articular cavities. Note: The fibula is not included in the knee joint (contrast to the humerus in the elbow; see p. 326). Instead, it forms a separate rigid articulation with the tibia. Fig. 32.2 Right knee joint Femur Popliteal surface Intercondylar notch Patella Lateral epicondyle Medial epicondyle Lateral epicondyle Lateral femoral condyle Medial femoral condyle Lateral femoral condyle Lateral tibial condyle Intercondylar eminence Medial tibial condyle Tibial plateau Tibiofibular joint Head of fibula Head of fibula Neck of fibula Tibial tuberosity Soleal line Fibula Fibula Tibia A Anterior view. 434 Tibia B Posterior view. Fig. 32.3 Patella Base 32 Knee & Leg Apex Anterior surface A Anterior view. Articular surface Femoropatellar joint Apex B Posterior view. Lateral femoral condyle Patella Fig. 32.4 Patellofemoral joint: Transverse section Lateral tibial condyle Head of fibula Distal view with right knee in slight flexion. Patellar lig. (quadriceps tendon) Prepatellar bursa Medial facet Tibial tuberosity Fibula Patella Lateral facet Radiographic view in Fig. 35.11B Joint space Tibia Patellar surface of femur Fibrous membrane C Lateral view. Lateral collateral lig. Lateral femoral condyle Common fibular n. Synovial membrane Medial collateral lig. Cruciate ligs. Medial femoral condyle Popliteal a. and v. Tibial n. Gastrocnemius 435 Lower Limb Knee Joint: Capsule, Ligaments & Bursae Table 32.1 Ligaments of the knee joint Fig. 32.5 Ligaments of the knee joint Extrinsic ligaments Anterior view of right knee. Patellar lig. Medial longitudinal patellar retinaculum Anterior side Lateral longitudinal patellar retinaculum Femur Medial transverse patellar retinaculum Lateral transverse patellar retinaculum Medial and lateral sides Posterior side Medial (tibial) collateral lig. Vastus intermedius tendon of insertion Lateral (fibular) collateral lig. Oblique popliteal lig. Arcuate popliteal lig. Vastus lateralis Vastus medialis Intrinsic ligaments Anterior cruciate lig. Posterior cruciate lig. Rectus femoris tendon of insertion Transverse lig. of knee Posterior meniscofemoral lig. Lateral transverse patellar retinaculum Medial collateral lig. Lateral longitudinal patellar retinaculum Medial transverse patellar retinaculum Lateral collateral lig. Medial longitudinal patellar retinaculum Head of fibula Patellar lig. Tibial tuberosity Fibula Tibia Interosseous membrane 436 Posterior view of right knee. The joint cavity communicates with periarticular bursae at the subpopliteal recess, semimembranosus bursa, and medial subtendinous bursa of the gastrocnemius. Clinical box 32.2 Gastrocnemio-semimembranosus bursa (Baker’s cyst) Painful swelling behind the knee may be caused by a cystic outpouching of the joint capsule (synovial popliteal cyst). This frequently results from an increase in intra-articular pressure (e.g., in rheumatoid arthritis). 32 Knee & Leg Fig. 32.6 Capsule, ligaments, and periarticular bursae Femur Medial subtendinous bursa of gastrocnemius Lateral subtendinous bursa of gastrocnemius Oblique popliteal lig. Semimembranosus bursa Lateral collateral lig. Medial collateral lig. Arcuate popliteal lig. Axial MRI of a Baker’s cyst in the right popliteal fossa, inferior view. Baker’s cysts often occur in the medial part of the popliteal fossa between the semimem­ branosus tendon and the medial head of the gas­ trocnemius at the level of the posteromedial femoral condyle. Popliteus Subpopliteal recess Fibula Tibia 437 Lower Limb Knee Joint: Ligaments & Menisci Fig. 32.7 Collateral and patellar ligaments of the knee joint Right knee joint. Each knee joint has medial and lateral collateral ligaments. The medial collateral ligament is attached to both the capsule and the medial meniscus, whereas the lateral collateral ligament has no direct contact with either the capsule or the lateral meniscus. Both collateral ligaments are taut when the knee is in extension and stabilize the joint in the coronal plane. Femur Quadriceps femoris tendon Femoropatellar joint Femur Medial epicondyle Quadriceps femoris tendon Medial femoral condyle Medial meniscus Patellar lig. Medial collateral lig. Patella Lateral epicondyle Lateral femoral condyle Fibula Tibia, medial surface Lateral collateral lig. Posterior lig. of fibular head Patellar surface of femur Lateral meniscus Patellar lig. Anterior lig. of fibular head A Medial view. Tibial tuberosity Fibula B Lateral view. 438 Fig. 32.8 Menisci in the knee joint Right tibial plateau, proximal view. Medial meniscus Injury to the menisci Transverse lig. of knee The less mobile medial meniscus (see Fig. 32.9) is more susceptible to injury than the lateral meniscus. Trauma generally results from sudden extension or rotation of the flexed knee while the leg is fixed. 32 Knee & Leg Clinical box 32.3 Patellar lig. Anterior cruciate lig. Tibiofibular joint Medial collateral lig. Lateral collateral lig. Posterior cruciate lig. Posterior meniscofemoral lig. Lateral meniscus Head of fibula A Bucket-handle tear. A Right tibial plateau with cruciate, patellar, and collateral ligaments divided. Medial meniscus Anterior cruciate lig. Synovial membrane B Attachment sites of menisci and cruciate ligaments. Red line indicates the tibial attachment of the synovial membrane that covers the cruciate ligaments. The cruciate ligaments lie in the subsynovial connective tissue. Radial tear of posterior horn. B Head of fibula Posterior cruciate lig. Lateral meniscus Fig. 32.9 Movements of the menisci Right knee joint. The medial meniscus, which is anchored more securely than the lateral meniscus, undergoes less displacement during knee flexion. Patella Patella Extension Patellar Patellar lig. ligament Lateral Lateral collateral collateral lig. ligament Flexion A Extension. Medial collateral Medial collateral ligament ligament B Flexion. Lateral collateral Lateral collateral ligament ligament C Tibial plateau, proximal view. 439 Lower Limb Cruciate Ligaments Fig. 32.10 Cruciate and collateral ligaments Right knee joint. The cruciate ligaments keep the articular surfaces of the femur and tibia in contact, while stabilizing the knee joint primarily in the sagittal plane. Portions of the cruciate ligaments are taut in every joint position. Intercondylar notch Patellar surface of femur Medial femoral condyle Anterior cruciate lig. Transverse lig. of knee Anterior cruciate lig. Posterior meniscofemoral lig. Lateral meniscus Posterior cruciate lig. Medial meniscus Lateral meniscus Lateral collateral lig. Medial collateral lig. Lateral collateral lig. Anterior lig. of fibular head Lateral femoral condyle Posterior lig. of fibular head Patellar lig. (reflected inferiorly) Head of fibula Patella Fibula Tibia A Anterior view. 440 B Posterior view. Interosseous membrane Fig. 32.11 Right knee joint in flexion Clinical box 32.4 Anterior view with joint capsule and patella removed. Patellar surface of femur Posterior cruciate lig. Medial femoral condyle Lateral femoral condyle Lateral collateral lig. Anterior cruciate lig. Cruciate ligament rupture destabilizes the knee joint, allowing the tibia to move forward (anterior “drawer sign”) or backward (posterior “drawer sign”) relative to the femur. Anterior cruciate ligament ruptures are approximately 10 times more common than posterior ligament ruptures. The most common mechanism of injury is an internal rotation trauma with the leg fixed. A lateral blow to the fully extended knee with the foot planted tends to cause concomitant rupture of the anterior cruciate and medial collateral ligaments, as well as tearing of the attached medial meniscus. 32 Knee & Leg Rupture of cruciate ligaments Medial meniscus Lateral meniscus Head of fibula Medial collateral lig. Tibial tuberosity Fibula Tibia Right knee in flexion, rupture of anterior A cruciate ligament, anterior view. Fig. 32.12 Cruciate and collateral ligaments in flexion and extension Right knee, anterior view. Taut ligament fibers shown in red. While most parts of the collateral ligaments are taut only in extension (A), the cruciate ligaments, or portions of them, are taut in flexion, extension and internal rotation (B,C). The cruciate ligaments thus help stabilize the knee in any joint position. A Extension. Flexion. B B Right knee in flexion, anterior “drawer sign,” medial view. During examination of the flexed knee, the tibia can be pulled forward. Flexion and internal rotation. C 441 Lower Limb Knee Joint Cavity Fig. 32.13 Opened joint capsule Fig. 32.14 Joint cavity Right knee, anterior view with patella reflected downward. Right knee, lateral view. The joint cavity was demonstrated by injecting liquid plastic into the knee joint and later removing the capsule. Quadriceps tendon Suprapatellar pouch Femur Femur Suprapatellar pouch Patella Femur, patellar surface Lateral femoral condyle Anterior cruciate lig. Medial femoral condyle Lateral collateral lig. Lateral meniscus Lateral collateral lig. Patellar lig. Subpopliteal recess Infrapatellar bursa Medial meniscus Alar folds Lateral meniscus Fibula Tibia Infrapatellar fat pad Patella, articular surface Joint capsule (cut edge) Suprapatellar pouch Fibula Tibia Fig 32.15 Relations of structures to the joint capsule and articular cavity Right knee joint, proximal view. Several joint structures provide strength or stability to the knee from outside of, or within, the joint space. • Extracapsular structures (lateral collateral ligament) remain outside of the joint capsule. • Intracapsular structures (medial collateral and cruciate ligaments) lie within the joint capsule but run in the subsynovial tissue outside the synovial membrane and are therefore also extra-articular. • Intra-articular structures (menici) lie within the articular cavity, enclosed by the synovial membrane, and are bathed in synovial fluid. Patellar lig. Intracapsular ligs. Cruciate ligs. Medial (tibial) collateral lig. Medial meniscus 442 Fibrous membrane Subintima Synovial Intima membrane Lateral meniscus Extracapsular lig. (lateral [fibular] collateral lig.) Fibula Joint capsule Fig. 32.17 Suprapatellar pouch during flexion Lateral view. Right knee joint, medial view. Suprapatellar pouch Femur 32 Knee & Leg Fig. 32.16 Right knee joint: Midsagittal section Sites of attachment of the joint capsule Suprapatellar pouch A Neutral (0-degree) position. Quadriceps tendon Patella Quadriceps femoris Prepatellar bursa Patellar lig. Patella Infrapatellar fat pad Patellar lig. Anterior intercondylar area Infrapatellar bursa B 80 degrees of flexion. Tibia Anterior cruciate lig. C 130 degrees of flexion. Clinical box 32.5 The ballottable patella sign of knee effusion Intra-articular effusion due to inflammatory changes or injury can be differentiated from swelling of the joint capsule by pushing down on the patella of the extended knee. If there is excessive fluid in the joint, the patella will rebound when released, signifying a positive test. Patella Effusion Femur Effusion Tibia Fibula 443 Lower Limb Muscles of the Leg: Anterior & Lateral Compartments Fig. 32.18 Muscles of the anterior compartment of the leg Right leg. Muscle origins shown in red, insertions in blue. Rectus femoris Femur Gracilis Vastus lateralis Sartorius Iliotibial tract Vastus medialis Patella Head of fibula Fibularis longus Tibial tuberosity Patellar lig. Tibial tuberosity Pes anserinus (common tendon of insertion of sartorius, gracilis, and semitendinosus) Gastrocnemius, medial head Fibularis longus Tibialis anterior Extensor digitorum longus Soleus Tibia Extensor hallucis longus Tibialis anterior Extensor digitorum longus Extensor hallucis longus Fibularis brevis Medial malleolus Fibularis tertius (variable) Extensor hallucis brevis Interossei Extensor digitorum brevis Fibularis tertius Extensor hallucis brevis Tibialis anterior Extensor digitorum longus Extensor hallucis longus A All muscles shown. 444 Extensor digitorum longus B Removed: Tibialis anterior and fibularis longus; extensor digitorum longus tendons (distal portions). Note: The fibularis tertius is a division of the extensor digitorum longus. Right leg. The triceps surae is comprised of the soleus and two heads of the gastrocnemius. Biceps femoris, long head Patella Rectus femoris 32 Knee & Leg Fig. 32.19 Muscles of the lateral compartment of the leg Vastus lateralis Biceps femoris, short head Iliotibial tract Patella Biceps femoris, common tendon of insertion Fibularis longus Interosseous membrane Patellar lig. Head of fibula Lateral tibial condyle Gastrocnemius, lateral head Tibialis anterior Fibularis longus Extensor digitorum longus Tibialis anterior Soleus Extensor hallucis longus Extensor digitorum longus Triceps surae Fibularis brevis Fibularis tertius Fibularis brevis Extensor digitorum brevis Lateral malleolus, fibula Extensor hallucis brevis and extensor digitorum brevis Fibularis tertius (variable) Calcaneal (Achilles’) tendon Fibularis brevis Tibialis anterior Fibularis tertius Extensor hallucis brevis Extensor digitorum longus Extensor hallucis longus Extensor digitorum brevis Calcaneus Fibularis longus Fibularis brevis Extensor digitorum longus Extensor hallucis longus C Removed: All muscles. 445 Lower Limb Muscles of the Leg: Posterior Compartment Fig. 32.20 Muscles of the posterior compartment of the leg Right leg. Muscle origins shown in red, insertions in blue. Gracilis Semitendinosus Iliotibial tract Semimembranosus Plantaris Gastrocnemius, medial head Plantaris Biceps femoris Gastrocnemius, medial head Gastrocnemius, lateral head Biceps femoris Popliteus Gastrocnemius, lateral head Fibularis longus Soleus Plantaris tendon Fibularis longus Fibularis longus Flexor digitorum longus Calcaneal (Achilles’) tendon Medial malleolus Tibialis posterior Flexor digitorum longus Soleus Flexor hallucis longus Lateral malleolus Calcaneus Fibularis brevis Fibularis longus A Note: The bulge of the calf is produced mainly by the triceps surae (soleus and the two heads of the gastrocnemius). Calcaneal (Achilles’) tendon Flexor hallucis longus Fibularis brevis Fibularis brevis Flexor hallucis longus 446 Flexor digitorum longus Tibialis posterior Flexor digitorum longus Flexor hallucis longus B Removed: Gastrocnemius (both heads). Calcaneus Fibularis brevis Fibularis longus Gastrocnemius, lateral head Plantaris Gastrocnemius, medial head Gastrocnemius, lateral head Popliteus Popliteus Biceps femoris Biceps femoris Fibularis longus Fibularis longus Soleus 32 Knee & Leg Plantaris Gastrocnemius, medial head Soleus Tibialis posterior Tibialis posterior Flexor digitorum longus Flexor digitorum longus Flexor hallucis longus Flexor hallucis longus Interosseous membrane Fibularis brevis Crural chiasm (intersection of two tendons) Plantaris Triceps surae Plantaris Triceps surae Tibialis posterior Fibularis brevis Tibialis anterior Fibularis longus Plantar chiasm (intersection of two tendons) Tibialis posterior Fibularis brevis Tibialis anterior Flexor hallucis longus Flexor digitorum longus Flexor hallucis longus Flexor digitorum longus C Removed: Triceps surae, plantaris, popliteus, fibularis longus, and fibularis brevis muscles. DRemoved: All muscles. 447 Lower Limb Muscle Facts (I) he muscles of the leg control the flexion/extension and inversion/ T eversion of the foot, which provide stability to the lower limb during movements at the knee and hip joint. Femur Fig. 32.21 Muscles of the lateral compartment of the leg Right leg and foot. Patella Lateral tibial condyle Head of fibula Lateral tibial surface 1st metatarsal Interosseous membrane Medial cuneiform Cuboid ① Fibularis longus tendon ② Fibularis longus Course of the fibularis longus tendon, C plantar view. Fibularis brevis Fibularis muscles, anterior view, schematic. A Lateral malleolus Calcaneus Lateral compartment, right lateral view. B Table 32.2 448 Fibularis longus tendon Cuboid Fibularis brevis tendon Tuberosity of 5th metatarsal Lateral compartment Muscle Origin Insertion ① Fibularis longus Fibula (head and proximal two thirds of the lateral surface, arising partly from the intermuscular septa) Medial cuneiform (plantar side), 1st metatarsal (base) ② Fibularis brevis Fibula (distal half of the lateral surface), intermuscular septa 5th metatarsal (tuberosity at the base, with an occasional division to the dorsal aponeurosis of the 5th toe) Innervation Superficial fibular n. (L5, S1) Action • Talocrural joint: plantar flexion • Subtalar joint: eversion (pronation) • Supports the transverse arch of the foot • Talocrural joint: plantar flexion • Subtalar joint: eversion (pronation) Fig. 32.22 Muscles of the anterior compartment of the leg Right leg, anterior view. Femur 32 Knee & Leg Lateral epicondyle Lateral tibial condyle Head of fibula Tibial tuberosity 1 3 2 Shaft of tibia Tibialis anterior 4 A Schematic. Table 32.3 B Anterior compartment. Extensor digitorum longus Anterior compartment Muscle Origin Insertion Innervation Action ① Tibialis anterior Tibia (upper two thirds of the lateral surface), interosseous membrane, and superficial crural fascia (highest part) Medial cuneiform (medial and plantar surface), first metatarsal (medial base) Deep fibular n. (L4, L5) • Talocrural joint: dorsiflexion • Subtalar joint: inversion (supination) Deep fibular n. (L4, L5) • Talocrural joint: dorsiflexion • Subtalar joint: active in both eversion and inversion (pronation/supination), depending on the initial position of the foot • Extends the MTP and IP joints of the big toe 2nd to 5th toes (at the dorsal aponeuroses at the bases of the distal phalanges) Deep fibular n. (L4, L5) • Talocrural joint: dorsiflexion • Subtalar joint: eversion (pronation) • Extends the MTP and IP joints of the 2nd to 5th toes 5th metatarsal (base) Deep fibular n. (L4, L5) • Talocrural joint: dorsiflexion • Subtalar joint: eversion (pronation) ② Extensor hallucis longus Fibula (middle third of the medial surface), interosseous membrane 1st toe (at the dorsal aponeurosis at the base of its distal phalanx) ③ Extensor digitorum longus Fibula (head and medial surface), tibia (lateral condyle), and interosseous membrane ④ Fibularis tertius Distal fibula (anterior border) Extensor hallucis longus Fibularis tertius Lateral malleolus Fibularis tertius tendon Medial malleolus Extensor digitorum longus tendon Extensor hallucis longus tendon 1st through 5th distal phalanges IP, interphalangeal; MTP, metatarsophalangeal. 449 Lower Limb Muscle Facts (II) Fig. 32.23 Muscles of the posterior compartment of the leg: Superficial flexors The muscles of the posterior compartment are divided into two groups: the superficial and deep flexors. These groups are separated by the transverse intermuscular septum. Right leg, posterior view. Femur ③ Medial epicondyle ① Lateral epicondyle Plantaris Gastrocnemius, lateral head (cut) Plantaris Medial femoral condyle ② Gastrocnemius, medial head (cut) Medial tibial condyle Head of fibula Tendinous arch of soleus Plantaris tendon Gastrocnemius, lateral head A Foot in plantar flexion, schematic. Triceps surae Soleus Gastrocnemius, medial head Gastrocnemius, medial head Triceps surae Gastrocnemius, lateral head Soleus Plantaris tendon Calcaneal (Achilles’) tendon Medial malleolus Lateral malleolus Talus Navicular 1st metatarsal 450 Talus Subtalar joint Calcaneus C Superficial flexors with gastrocnemius removed (portions of medial and lateral heads). Superficial flexors of the posterior compartment Muscle Origin ①G astrocnemius Triceps surae Femur (medial head: superior posterior part of the medial femoral condyle. lateral head: lateral surface of lateral femoral condyle) ② Soleus Fibula (head and neck, posterior surface), tibia (soleal line via a tendinous arch) ③ Plantaris Calcaneal (Achilles’) tendon Calcaneal tuberosity B Superficial flexors. Table 32.4 Talocrural joint Femur (lateral epicondyle, proximal to lateral head of gastrocnemius) Insertion Calcaneal tuberosity via the calcaneal (Achilles’) tendon Calcaneal tuberosity Innervation Action Tibial n. (S1, S2) • Talocrural joint: plantar flexion when knee is extended (gastrocnemius) • Knee joint: flexion (gastrocnemius) • Talocrural joint: plantar flexion (soleus) Negligible; may act with gastrocnemius in plantar flexion Fig. 32.24 Posterior compartment of the leg: Deep flexors Right leg with foot in plantar flexion, posterior view. F Popliteus Medial tibial condyle Head of fibula A Medial tibial condyle Head of fibula Soleal line 32 Knee & Leg Femur S D Tibialis posterior Crural chiasm Flexor digitorum longus Plantar chiasm Tibialis posterior Posterior surface of tibia Flexor hallucis longus Posterior surface of fibula A Schematic. Tibialis posterior Interosseous membrane Fibula Calcaneal tuberosity Lateral malleolus Tuberosity of cuboid Talus Tibialis posterior tendon Tuberosity of 5th metatarsal Medial cuneiform Medial malleolus Table 32.5 Calcaneus Lateral malleolus Tibialis posterior tendon Tibialis posterior tendons Flexor hallucis longus tendon DInsertion of the tibialis posterior. Medial malleolus Calcaneal tuberosity Tuberosity of 5th metatarsal 1st through 5th metatarsals Flexor digitorum longus tendons B Deep flexors. C Tibialis posterior. Deep flexors of the posterior compartment Muscle Origin Insertion Innervation Action ① Tibialis posterior Interosseous membrane, adjacent borders of tibia and fibula Navicular tuberosity; cuneiforms (medial, intermediate, and lateral); 2nd to 4th metatarsals (bases) Tibial n. (L4, L5) • Talocrural joint: plantar flexion • Subtalar joint: inversion (supination) • Supports the longitudinal and transverse arches ② Flexor digitorum longus Tibia (middle third of posterior surface) 2nd to 5th distal phalanges (bases) ③ Flexor hallucis longus Fibula (distal two thirds of posterior surface), adjacent interosseous membrane 1st distal phalanx (base) ④ Popliteus Lateral femoral condyle, posterior horn of the lateral meniscus Posterior tibial surface (above the origin at the soleus) Tibial n. (L5–S2) Tibial n. (L4–S1) • Talocrural joint: plantar flexion • Subtalar joint: inversion (supination) • MTP and IP joints of the 2nd to 5th toes: plantar flexion • Talocrural joint: plantar flexion • Subtalar joint: inversion (supination) • MTP and IP joints of the 1st toe: plantar flexion • Supports the medial longitudinal arch Knee joint: flexes and unlocks the knee by externally rotating the femur on the fixed tibia IP, interphalangeal; MTP, metatarsophalangeal. 451 33 Ankle & Foot Lower Limb Bones of the Foot Fig. 33.1 Subdivisions of the pedal skeleton Fig. 33.2 Bones of the foot Right foot, dorsal view. Descriptive anatomy divides the skeletal elements of the foot into the tarsus, metatarsus, and forefoot (ante­ tarsus). Functional and clinical criteria divide the pedal skeleton into hindfoot, midfoot, and forefoot. 1st distal phalanx Head 1st proximal phalanx Antetarsus (phalanges) Forefoot 1st metatarsal Metatarsus (metatarsal bones) Shaft 5th distal phalanx Base 5th middle phalanx Head 5th proximal phalanx Shaft 5th metatarsal Base Midfoot Medial cuneiform Tarsus (tarsal bones) Intermediate cuneiform Hindfoot Lateral cuneiform Navicular Tuberosity of 5th metatarsal Head Talus Cuboid Neck Body Calcaneus Talus Neck Body Head Posterior process Intermediate cuneiform Navicular Medial cuneiform Calcaneus Calcaneal tuberosity Lateral process of calcaneal tuberosity Right foot, lateral view. B 452 Calcaneal tuberosity A Right foot, dorsal (superior) view. 1st metatarsal Cuboid Medial process of calcaneal tuberosity Lateral cuneiform Tuberosity of 5th metatarsal 5th metatarsal 5th proximal phalanx 5th middle phalanx 5th distal phalanx 33 Ankle & Foot 1st distal phalanx 5th distal phalanx 1st proximal phalanx 5th middle phalanx Sesamoids 5th proximal phalanx Clinical box 33.1 The functional position of the foot Right foot, lateral view. In the neutral (0°) position, the skeleton of the foot is angled approximately 90° relative to the skeleton of the leg. This plantigrade foot position is termed the “functional position” and is an important basis for normal standing and walking. 1st metatarsal 5th metatarsal Medial cuneiform Intermediate cuneiform Tuberosity of 5th metatarsal Lateral cuneiform Groove for fibularis longus tendon Navicular Tuberosity of cuboid Head Cuboid Neck Body Talus Calcaneus Posterior process Sustentaculum tali C Right foot, plantar (inferior) view. Talus Neck Head Navicular 1st metatarsal 1st proximal phalanx Head Shaft Base Body Medial tubercle Base Lateral tubercle Shaft Head Posterior process of talus Calcaneal tuberosity Medial cuneiform 1st distal phalanx DRight foot, medial view. Cuboid Sustentac­ ulum tali Medial process of calcaneal tuberosity 453 Joints of the Foot (I) Lower Limb Fig. 33.3 Joints of the foot Right foot with talocrural joint in plantar flexion. Talocrural (ankle) joint Subtalar (talocalcaneal) joint Tranverse tarsal joint Talonavicular joint Calcaneocuboid joint Intercuneiform joints Cuneocuboid joint Cuneonavicular joint Tarsometatarsal joints Intermetatarsal joints Metatarsophalangeal joints Interphalangeal joint of the hallux Proximal interphalangeal joints Distal interphalangeal joints A Anterior view. Fibula Lateral malleolus Interosseous talocalcanean ligament Calcaneus Transverse tarsal joint Talonavicular joint Calcaneo­ cuboid joint Cuboid Intercuneiform joints Tarsometatarsal joints (Lisfranc’s joint line) Abductor digiti minimi Interossei Tibia Talocrural (ankle) joint Medial malleolus Talus Navicular Cuneonavicular joint Intermediate cuneiform Lateral cuneiform Medial cuneiform Abductor hallucis 1st metatarsal Proximal inter­ phalangeal joints 5th middle phalanx Distal inter­ phalangeal joints 1st metatarso­ phalangeal joint 1st proximal phalanx 1st distal phalanx B Superior view of coronal section. 454 Fig. 33.4 Proximal articular surfaces Fig. 33.5 Distal articular surfaces Right foot, proximal view. Right foot, distal view. C B Medial malleolar surface Lateral malleolar surface Head of talus (with articular surface for navicular) A Metatarsophalangeal joints. C Sustentaculum tali 33 Ankle & Foot B D A Superior trochlear surface of talus Base of 1st proximal phalanx A D Calcaneus 1st through 5th metatarsals Calcaneus (with articular surface for cuboid) Talus A Talonavicular and calcaneocuboid joints. Navicular Base of 5th metatarsal Base of 1st metatarsal Tuberosity of 5th metatarsal Navicular tuberosity Calcaneus B Tarsometatarsal joints. B Cuneonavicular and calcaneocuboid joints. Intermediate Lateral cuneiform cuneiform Calcaneus (with articular surface for cuboid) Talus Navicular Intermediate cuneiform Cuboid Medial cuneiform Cuboid Medial cuneiform Tuberosity of 5th metatarsal Lateral cuneiform C Cuneonavicular and calcaneocuboid joints. Calcaneus C Tarsometatarsal joints. Base Navicular 1st metatarsal Shaft Head Cuboid DTalonavicular and calcaneocuboid joints. 1st through 5th metatarsals Sesamoids DMetatarsophalangeal joints. 455 Joints of the Foot (II) Lower Limb Fig. 33.6 Talocrural and subtalar joints Right foot. The talocrural (ankle) joint is formed by the distal ends of the tibia and fibula (ankle mortise) articulating with the trochlea of the talus. The subtalar joint consists of an anterior and a posterior compart­ ment (the talocalcaneal and talocalcaneonavicular joints, respectively) divided by the interosseous talocalcaneal ligament (see p. 458). Tibia Fibula Clinical box 33.2 Range of motion of the forefoot and hindfoot Right foot, anterior view. Ankle mortise Medial malleolus Lateral malleolus Talocrural joint Navicular Talus Subtalar (talo­ calcaneal) joint Sustentaculum tali 1st metatarsal 60° 30° Tuberosity of 5th metatarsal A Eversion and pronation of the forefoot. Sesamoids B Inversion and supina­ tion of the forefoot. Calcaneal tuberosity A Posterior view with foot in neutral (0-degree) position. Ankle mortise Tibialis anterior Tibia Medial malleolar articular surface Medial malleolus Talus, superior trochlear surface Tibialis posterior Flexor digitorum longus Flexor hallucis longus Extensor hallucis Extensor digitorum Tibiofibular syndesmosis Talocrural joint Lateral malleolar articular surface Lateral malleolus Subtalar (talo­ calcaneal) joint Fibularis brevis Fibularis longus Posterior tibial a. and vv. Abductor hallucis B Coronal section, proximal view. The talocrural joint is plantar flexed, and the subtalar joint has been sectioned through its posterior compartment. 456 Quadratus plantae Calcaneus Flexor digitorum brevis Fibula Fig. 33.7 Talocrural and subtalar joints: Sagittal section Right foot, medial view. Interosseous talocalcaneal lig. Tibia Talocrural joint Navicular Calcaneal (Achilles’) tendon Cuneiforms 33 Ankle & Foot Talocalcaneonavicular joint (anterior compartment of subtalar joint) Talus Talocalcaneal joint (posterior compartment of subtalar joint) 2nd metatarsal Bursa of calcaneal tendon Calcaneus Short pedal muscles Fig. 33.8 Talocrural joint Plantar Plantar calcaneo­ aponeurosis navicular lig. Right foot. The talocrural (ankle) joint is tighter and more stable with the foot in dorsiflexion, when the wider, anterior part of the trochlea (of the talus) is wedged within the ankle mortise. Accordingly the joint is looser and less stable in plantar flexion. Tibia Tibia Fibula Fibula Medial malleolus Lateral malleolus Ankle mortise Medial malleolus Lateral malleolus Talus Navicular Navicular Sustentac­ ulum tali Superior trochlear surface of talus (anterior diameter) A Anterior view. Calcaneus Superior trochlear surface of talus (posterior diameter) B Posterior view. Head Anterior diameter Neck Medial malleolar surface Inferior articular surface Fibula Tibia Lateral malleolus Superior trochlear surface Posterior diameter Medial malleolus Lateral malleolar surface Lateral tubercle C Proximal (superior) view of talus. Lateral malleolar articular surface Medial malleolar articular surface DDistal (inferior) view of ankle mortise. 457 Lower Limb Joints of the Foot (III) Fig. 33.9 Subtalar joint and ligaments ment: the posterior compartment (talocalcaneal joint) and the anterior compartment (talocalcaneonavicular joint). Right foot with opened subtalar joint. The subtalar joint consists of two distinct articulations separated by the interosseous talocalcaneal liga­ 5th metatarsal Medial cuneiform Navicular Cuboid Tunnel for fibularis longus tendon Plantar calcaneonavicular lig. Long plantar lig. Calcaneus Sustentaculum tali Talus Medial cuneiform Navicular Plantar calcaneo­ navicular lig. B Plantar view. The plantar calcaneonavicular (“spring”) ligament com­ pletes the bony socket of the talocalcaneal joint. The long plantar ligament converts the tuberosity of the cuboid bone into a tunnel for the fibularis longus tendon (arrow). Cuboid Bifurcate lig. Dorsal calcaneo­ cuboid lig. Talus Anterior compart­ ment Posterior compart­ ment Subtalar joint Tibia Calcaneus Interosseous talocalcaneal lig. Medial malleolus Navicular surface Talus Navicular A Dorsal view. Medial cuneiform Interosseous talocalcaneal lig. 1st metatarsal Sustentaculum tali Calcaneus Plantar Long plantar lig. aponeurosis C Medial view. The interosseous talocalcaneal ligament has been divided and the talus displaced upward. Note the course of the plantar calca­ 458 Plantar calcaneo­ navicular lig. neonavicular ligament, which functions with the long plantar ligament and plantar aponeurosis to support the longitudinal arch of the foot. Fig. 33.10 Talus and calcaneus Lateral malleolar surface Navicular articular surface Anterior talar articular surface Superior trochlear surface Cuboid articular surface Medial malleolar surface Sinus tarsi Medial tubercle Posterior process of talus Sulcus calcanei Posterior talar articular surface Groove for flexor hallucis longus tendon Lateral tubercle A Dorsal (superior) view. 33 Ankle & Foot The two tarsal bones have been separated at the subtalar joint to demonstrate their articular surfaces. Sustentac­ ulum tali Middle talar articular surface Calcaneal body Superior trochlear surface Lateral malleolar surface Navicular articular surface Posterior calcaneal articular surface Posterior talar articular surface Middle talar articular surface Cuboid articular surface Anterior calcaneal articular surface Navicular articular surface Sinus tarsi Cuboid articular surface B Lateral view. Middle calcaneal articular surface Sulcus tali Posterior calcaneal articular surface Groove for flexor hallucis longus tendon Calcaneal tuberosity Medial tubercle Medial process Lateral process C Plantar view. Lateral tubercle Groove for flexor hallucis longus tendon Superior trochlear surface Medial malleolar surface Navicular articular surface Posterior talar articular surface Anterior talar articular surface Sustentac­ ulum tali Cuboid articular surface Calcaneus Middle talar articular surface DMedial view. 459 Lower Limb Ligaments of the Ankle & Foot The ligaments of the foot are classified as belonging to the talocrural joint, subtalar joint, metatarsus, forefoot, or sole of the foot. The medial and lateral collateral ligaments, along with the syndesmotic ligaments, are of major importance in the stabilization of the subtalar joint. Fig. 33.11 Ligaments of the ankle and foot Right foot. See p. 458 for inferior view. Tibia Fibula Ligaments of the talocrural joint Table 33.1 Anterior talofibular lig. Lateral ligs.* Posterior talofibular lig. Calcaneofibular lig. Anterior tibiotalar part Anterior tibiofibular lig. Medial malleolus Medial ligs.* Deltoid lig. Talus Lateral malleolus Deltoid lig. Anterior talo­ fibular lig. Dorsal talonavicular lig. Bifurcate lig. Navicular Cuboid Posterior tibiotalar part Tibionavicular part Tibiocalcaneal part Syndesmotic ligs. of the ankle mortise Anterior tibiofibular lig. Posterior tibiofibular lig. *The medial and lateral ligs. are also known as the medial and lateral collateral ligs. Dorsal tarsal ligs. Dorsal metatarsal ligs. 1st metatarsal Metatarso­ phalangeal joint capsules Interosseous membrane Tibia Fibula 1st proximal phalanx 1st distal phalanx A Anterior view with talocrural joint in plan­ tar flexion. Medial malleolus Deltoid lig. Talus Posterior tibio­ fibular lig. Lateral malleolus Posterior talo­ fibular lig. Calcaneofibular lig. Calcaneus Posterior view in plantigrade foot position. B 460 33 Ankle & Foot Tibia Posterior tibio­ fibular lig. Medial malleolus Anterior tibio­ talar part Talus Tibionavicular part Dorsal talonavicular lig. Tibiocalcaneal part Navicular Deltoid lig. Posterior tibiotalar part 1st metatarsal 1st proximal phalanx Sustentac­ ulum tali 1st distal phalanx Calcaneus Medial cuneiform Dorsal tarsal ligs. Long plantar lig. Plantar calcaneo­ navicular lig. C Medial view. Tibia Fibula Posterior tibiofibular lig. Anterior tibiofibular lig. Tibiofibular syndesmosis (syndesmotic ligs.) Dorsal talonavicular lig. Lateral malleolus Talus Navicular Dorsal tarsal ligs. Posterior talofibular lig. Metatarsophalangeal joint capsules Anterior talo­ fibular lig. Calcaneo­ fibular lig. Calcaneus Long plantar lig. Bifurcate lig. DLateral view. Interosseous talocalcaneal lig. Cuboid Dorsal calcaneocuboid ligs. 5th metatarsal 461 Lower Limb Plantar Vault & Arches of the Foot Fig. 33.12 The plantar vault Right foot. The forces of the foot are distributed among two lateral (fibular) and three medial (tibial) rays. The arrangement of these rays creates a longitudinal and a transverse arch in the sole of the foot, help­ ing the foot adapt to uneven terrain and absorb vertical loads. Head of 1st metatarsal Medial rays Head of 5th metatarsal Lateral rays B Posteromedial view. Cuneiforms Navicular C Superior view. The area outlined in red by interconnecting the bony points of support for the plantar vault forms a triangle. By contrast, the area of ground contact defined by the plantar soft tissues (the foot­ print or podogram) is considerably larger. Cuboid Talus Calcaneus A Superior view. Fig. 33.13 Stabilizers of the transverse arch Right foot. The transverse pedal arch is supported by both active and passive stabilizing structures (muscles and ligaments, respectively). Calcaneal tuberosity Note: The arch of the forefoot has only passive stabilizers, whereas the arches of the metatarsus and tarsus have only active stabilizers. Plantar ligs. Deep transverse metatarsal lig. Plantar ligs. Proximal phalanx of great toe Metatarso­ phalangeal joint of great toe Adductor hallucis, transverse head Fibularis longus Base of 1st proximal phalanx Deep transverse metatarsal lig. Adductor hallucis, transverse head 1st metatarsal Adductor hallucis, oblique head Cuboid B Anterior arch (forefoot), proximal view. Medial cuneiform C Metatarsal arch, proximal view. Base of 1st metatarsal Adductor hallucis, oblique head Intermediate cuneiform Base of 5th meta­ tarsal Lateral cuneiform Cuboid Tibialis posterior Medial malleolus Sustentac­ ulum tali Calcaneus Plantar view. A 462 Talus DTarsal region, proximal view. Medial cuneiform Tibialis posterior Fibularis longus Tuberosity of 5th metatarsal Fig. 33.14 Stabilizers of the longitudinal arch Right foot, medial view. Navicular Flexor digitorum longus Talus Medial cuneiform Medial malleolus Medial tubercle Plantar Long plantar aponeurosis lig. Plantar calcaneocuboid lig. Plantar calcaneonavicular lig. 33 Ankle & Foot Flexor hallucis longus Sustentac­ ulum tali A Passive stabilizers of the longitudinal arch. The main passive stabilizers of the longitudinal arch are the plantar aponeurosis (strongest component), the long plantar ligament, and the plantar calcaneona­ vicular ligament (weakest component). Fibularis longus tendon Flexor hallucis brevis Plantar interossei Calcaneal (Achilles’) tendon Dorsal interossei Adductor hallucis Quadratus plantae Abductor hallucis Lumbrical Flexor digitorum brevis Plantar aponeurosis B Active stabilizers of the longitudinal arch. Sagittal section at the level of the second ray. The major active stabilizers of the foot are the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, and abductor digiti minimi. 463 Lower Limb Muscles of the Sole of the Foot Fig. 33.15 Plantar aponeurosis Right foot, plantar view. The plantar aponeurosis is a tough aponeurotic sheet, thickest at the center, that blends with the dorsal fascia (not shown) at the borders of the foot. Annular ligs. Cruciform ligs. Superficial transverse metatarsal lig. Transverse fascicles Flexor digiti minimi brevis 3rd plantar interosseus Tuberosity of 5th metatarsal Abductor digiti minimi Lateral plantar septum Plantar aponeurosis Fibularis longus Fig. 33.16 Intrinsic muscles of the sole of the foot Right foot, plantar view. Flexor hallucis brevis Medial plantar septum Abductor hallucis Tibialis posterior Flexor digitorum longus Flexor hallucis longus Calcaneal tuberosity Flexor digitorum brevis tendons 3rd plantar interosseus 4th dorsal interosseus Flexor digiti minimi brevis Flexor hallucis longus tendon Lumbricals Flexor hallucis brevis Flexor digitorum brevis Abductor digiti minimi Abductor hallucis Fibularis longus Plantar aponeurosis Tibialis posterior Flexor digitorum longus Flexor hallucis longus Superficial (first) layer. Removed: Plantar aponeurosis, including the A superficial transverse metacarpal ligament. 464 33 Ankle & Foot Flexor digitorum brevis tendons Flexor digitorum longus tendons Flexor hallucis longus tendon Adductor hallucis, transverse head Lumbricals 3rd plantar interosseus Flexor hallucis brevis 4th dorsal interosseus Flexor digitorum longus Flexor digiti minimi brevis Abductor digiti minimi Fibularis longus tendon Abductor hallucis Quadratus plantae Fibularis longus Tibialis posterior Flexor digitorum brevis Flexor digitorum longus Flexor hallucis longus Flexor digitorum longus tendons Flexor digitorum brevis tendons Flexor hallucis longus Lumbricals Transverse head B Second layer. Removed: Flexor digitorum brevis. Oblique head Plantar and dorsal interossei Opponens digiti minimi Adductor hallucis Flexor hallucis brevis, medial and lateral heads Abductor hallucis Flexor digiti minimi brevis Tuberosity of 5th metatarsal Fibularis brevis Long plantar lig. Fibularis longus tendon Tibialis posterior tendon Quadratus plantae Fibularis longus Abductor digiti minimi C Third layer. Removed: Abductor digiti minimi, abductor hallucis, quadratus plantae, lumbricals, and tendons of insertion of the flexors digitorum and hallucis longus. Abductor hallucis Flexor digitorum longus Flexor hallucis longus 465 Muscles & Tendon Sheaths of the Foot Lower Limb Fig. 33.17 Deep intrinsic muscles of the sole of the foot Right foot, plantar view. Plantar ligs. 1st through 4th lumbricals Transverse head Oblique head Flexor digiti minimi brevis Adductor hallucis Flexor hallucis brevis 1st dorsal interosseus 3rd plantar interosseus 4th dorsal interosseus 2nd dorsal interosseus Abductor hallucis Adductor hallucis, oblique head 1st plantar interosseus Opponens digiti minimi Flexor hallucis brevis Tibialis anterior tendon Flexor digiti minimi brevis Fibularis longus tendon Plantar calcaneonavicular lig. Long plantar lig. Fibularis brevis Tibialis posterior tendon Quadratus plantae Fibularis longus Abductor digiti minimi Flexor digitorum longus Abductor hallucis Flexor digitorum brevis Plantar aponeurosis Flexor digiti minimi brevis A Fourth layer. Removed: Adductor hallucis, flexor digiti minimi brevis, and flexor hal­ lucis brevis. Flexor hallucis longus Flexor digitorum brevis 1st through 4th dorsal interossei Flexor hallucis brevis Abductor digiti minimi Abductor hallucis Adductor hallucis 1st through 3rd plantar interossei Adductor hallucis, transverse head Opponens digiti minimi 3rd plantar interosseus 4th dorsal interosseus 2nd plantar interosseus 3rd dorsal interosseus Adductor hallucis, oblique head Flexor digiti minimi brevis Abductor digiti minimi and fibularis brevis 1st dorsal interosseus 2nd dorsal interosseus 1st plantar interosseus Tibialis anterior Fibularis longus Tibialis posterior Flexor hallucis brevis Abductor digiti minimi Flexor digitorum brevis B Muscle origins are shown in red, insertions in blue. 466 Quadratus plantae Abductor hallucis Fig. 33.18 Tendon sheaths and retinacula of the ankle Fibularis longus Tibialis anterior Tibia Extensor digitorum longus Extensor hallucis longus Fibularis brevis Superior extensor retinaculum 33 Ankle & Foot Right foot. The superior and inferior extensor retinacula retain the long extensor tendons, the fibularis retinacula hold the fibular muscle ten­ dons in place, and the flexor retinaculum retains the long flexor tendons. Triceps surae Medial malleolus Inferior extensor retinaculum Lateral malleolus Fibularis brevis Tendon sheath Tibialis anterior Extensor hallucis brevis Fibularis tertius Tibia Extensor digitorum brevis Tuberosity of 5th metatarsal Interossei Extensor hallucis longus tendon Flexor digitorum longus Superior extensor retinaculum Extensor digitorum longus tendons Abductor digiti minimi Triceps surae Tibialis posterior Medial malleolus Inferior extensor retinaculum Flexor hallucis longus Extensor hallucis longus Tendon sheath Calcaneal (Achilles’) tendon Flexor retinaculum Flexor hallucis longus A Anterior view with talocrural joint in plantar flexion. Tuberosity of 5th metatarsal Flexor hallucis Tibialis longus anterior Fibularis longus Tibialis anterior Flexor digitorum longus Calcaneal tuberosity B Medial view. Extensor hallucis longus Triceps surae Extensor digitorum longus Fibularis brevis Fibula Superior extensor retinaculum Fibularis tertius Inferior extensor retinaculum Extensor digitorum brevis Extensor digitorum longus tendons Lateral malleolus Calcaneal (Achilles’) tendon Extensor hallucis longus tendon Extensor digitorum brevis tendons Superior fibular retinaculum Fibularis longus Inferior fibular retinaculum Fibularis brevis C Lateral view. Tibialis posterior Abductor digiti minimi Tuberosity of 5th metatarsal Dorsal aponeurosis 467 Lower Limb Muscle Facts (I) The dorsal surface (dorsum) of the foot contains only two muscles, the extensor digitorum brevis and the extensor hallucis brevis. The sole of the foot, however, is composed of four complex layers that maintain the arches of the foot. Fig. 33.19 Intrinsic muscles of the dorsum of the foot Right foot, dorsal view. Extensor digitorum brevis tendons 5th distal phalanx 1st proximal phalanx 5th middle phalanx 5th proximal phalanx S A Extensor hallucis brevis tendon 5th metatarsal Extensor hallucis brevis Medial cuneiform A Schematic. Extensor digitorum brevis Intermediate cuneiform Navicular Tuberosity of 5th metatarsal Superior trochlear surface Talus Calcaneus B Dorsal muscles of the foot. Table 33.2 Intrinsic muscles of the dorsum of the foot Muscle Origin ① Extensor digitorum brevis Calcaneus (dorsal surface) ② Extensor hallucis brevis Insertion 2nd to 4th toes (at dorsal aponeuroses and bases of the middle phalanges) 1st toe (at dorsal aponeurosis and proximal phalanx) MTP, metatarsophalangeal; PIP, proximal interphalangeal. 468 Innervation Deep fibular n. (L5, S1) Action Extension of the MTP and PIP joints of the 2nd to 4th toes Extension of the MTP joints of the 1st toe Fig. 33.20 Superficial intrinsic muscles of the sole of the foot Right foot, plantar view. 33 Ankle & Foot Cruciform ligs. Sesamoids A S D Flexor digitorum brevis Tuberosity of 5th metatarsal A First layer, schematic. Tuberosity of cuboid Abductor hallucis Abductor digiti minimi Plantar aponeurosis Calcaneal tuberosity B Intrinsic muscles of the sole, first layer. Table 33.3 Superficial intrinsic muscles of the sole of the foot Muscle Origin Insertion ① Abductor hallucis Calcaneal tuberosity (medial process); flexor retinaculum, plantar aponeurosis 1st toe (base of proximal phalanx via the medial sesamoid) ② Flexor digitorum brevis ③ Abductor digiti minimi Calcaneal tuberosity (medial tubercle), plantar aponeurosis Innervation Medial plantar n. (S1, S2) 2nd to 5th toes (sides of middle phalanges) 5th toe (base of proximal phalanx), 5th metatarsal (at tuberosity) Action • 1st MTP joint: flexion and abduction of the 1st toe • Supports the longitudinal arch • Flexes the MTP and PIP joints of the 2nd to 5th toes • Supports the longitudinal arch Lateral plantar n. (S1–S3) • Flexes the MTP joint of the 5th toe • Abducts the 5th toe • Supports the longitudinal arch MTP, metatarsophalangeal; PIP, proximal interphalangeal. 469 Lower Limb Muscle Facts (II) Fig. 33.21 Deep intrinsic muscles of the sole of the foot Right foot, plantar view, schematics. S ⑥ ④ J ③ K ⑤ A Flexor digitorum longus tendon A Second layer. Table 33.4 B Third layer. Deep intrinsic muscles of the sole of the foot Muscle Origin Insertion Innervation Action ① Quadratus plantae Calcaneal tuberosity (medial and plantar borders on plantar side) Flexor digitorum longus tendon (lateral border) Lateral plantar n. (S1–S3) Redirects and augments the pull of flexor digitorum longus ② Lumbricals (four muscles) Flexor digitorum longus tendons (medial borders) 2nd to 5th toes (at dorsal aponeuroses) ③ Flexor hallucis brevis Cuboid, lateral cuneiforms, and plantar calcaneocuboid lig. 1st toe (at base of proximal phalanx via medial and lateral sesamoids) ④ Adductor hallucis Oblique head: 2nd to 4th metatarsals (at bases) cuboid and lateral cuneiforms Transverse head: MTP joints of 3rd to 5th toes, deep transverse metatarsal lig. 1st proximal phalanx (at base, by a common tendon via the lateral sesamoid) ⑤ Flexor digiti minimi brevis 5th metatarsal (base), long plantar lig. 5th toe (base of proximal phalanx) ⑥ Opponens digiti minimi* Long plantar lig.; fibularis longus (at plantar tendon sheath) 5th metatarsal ⑦ Plantar interossei (three muscles) 3rd to 5th metatarsals (medial border) 3rd to 5th toes (medial base of proximal phalanx) 1st interosseus: 2nd proximal phalanx (medial base) ⑧ Dorsal interossei (four muscles) 1st to 5th metatarsals (by two heads on opposing sides) 2nd to 4th interossei: 2nd to 4th proximal phalanges (lateral base), 2nd to 4th toes (at dorsal aponeuroses) IP, interphalangeal; MTP, metatarsophalangeal. *May be absent. 470 C Fourth layer. 1st lumbrical: medial plantar n. (S2, S3) 2nd to 4th lumbrical: lateral plantar n. (S2, S3) Medial head: medial plantar n. (S1, S2) Lateral head: lateral plantar n. (S1, S2) Lateral plantar n., deep branch (S2, S3) Lateral plantar n., superficial branch (S2, S3) • Flexes the MTP joints of 2nd to 5th toes • Extension of IP joints of 2nd to 5th toes • Adducts 2nd to 5th toes toward the big toe • Flexes the first MTP joint • Supports the longitudinal arch • Flexes the first MTP joint • Adducts big toe • Transverse head: supports transverse arch • Oblique head: supports longitudinal arch Flexes the MTP joint of the little toe Pulls 5th metatarsal in plantar and medial direction • Flexes the MTP joints of 3rd to 5th toes • Extension of IP joints of 3rd to 5th toes • Adducts 3rd to 5th toes toward 2nd toe Lateral plantar n. (S2, S3) • Flexes the MTP joints of 2nd to 4th toes • Extension of IP joints of 2nd to 4th toes • Abducts 3rd and 4th toes from 2nd toe Fig. 33.22 Deep intrinsic muscles of the sole of the foot Right foot, plantar view. 33 Ankle & Foot Flexor digitorum longus tendons 1st dorsal interosseus 3rd plantar interosseus 1st through 4th lumbricals Medial cuneiform Tuberosity of 5th metatarsal Long plantar lig. Fibularis longus tendon Quadratus plantae Flexor digitorum longus Flexor digitorum brevis Lateral sesamoid Metatarso­ phalangeal joint capsules Opponens digiti minimi Flexor digiti minimi brevis Medial sesamoid Transverse head Oblique head Medial head Lateral head Adductor hallucis Flexor hallucis brevis Sustentaculum tali Calcaneus Fibularis longus tendon A Intrinsic muscles of the sole, second and fourth layers. Long plantar lig. Lateral process Tibialis posterior tendon Plantar calcaneonavicular lig. Medial process B Intrinsic muscles of the sole, third layer. 471 34 Neurovasculature Lower Limb Arteries of the Lower Limb Fig. 34.1 Arteries of the lower limb and the sole of the foot Adductor hiatus Abdominal aorta Common iliac a. Internal iliac a. Deep circumflex iliac a. Superior and inferior gluteal aa. Superficial epigastric a. External iliac a. Superficial circumflex iliac a. Inferior epigastric a. Piriformis Adductor magnus Medial superior genicular a. Middle genicular a. Medial inferior genicular a. External pudendal aa. Anterior tibial a. Lateral circumflex femoral a. Deep a. of the thigh 1st through 4th perforating aa. Posterior tibial a. Popliteal a. Lateral superior genicular a. Sural aa. Lateral inferior genicular a. Posterior tibial recurrent a. Anterior tibial recurrent a. Fibular a. Medial circumflex femoral a. Muscular brs. Femoral a. Adductor canal (with adductor magnus) Communicating br. Popliteal a. Lateral superior and inferior genicular aa. Adductor hiatus Descending genicular a. Medial superior and inferior genicular aa. Medial malleolar brs. Medial plantar a. Perforating br. Lateral malleolar brs. Calcaneal brs. B Right leg, posterior view. Anterior tibial recurrent a. Interosseous membrane Proper plantar digital aa. Anterior tibial a. Plantar metatarsal aa. Deep plantar arch Anterior lateral malleolar a. Lateral tarsal a. Arcuate a. Anterior medial malleolar a. Dorsal pedal a. Lateral plantar a. Dorsal metatarsal aa. Common plantar digital aa. Superficial br. Deep br. Abductor hallucis Medial plantar a. Posterior tibial a. A Right leg, anterior view. 472 C Sole of right foot, plantar view. Medial plantar a. Fig. 34.2 Segments of the femoral artery The blood supply to the lower limbs originates from the femoral artery. Color is used to identify the named distal segments of this vessel. Internal iliac a. External iliac a. Right leg. The artery passes posteriorly through the adductor muscles of the medial thigh to supply the muscles of the posterior compart­ ment via three to five perforating branches. Ligation of the femoral artery proximal to the origin of the deep artery of the thigh (left) is well tolerated owing to the collateral blood supply (arrows) from branches of the internal iliac artery that anastomose with the perfor­ ating branches. Inguinal lig. Deep a. of the thigh Adductor magnus Adductor longus 34 Neurovasculature Abdominal aorta Common iliac a. Fig. 34.3 Deep artery of the thigh Femoral a. 1st perforating a. Adductor canal 2nd perforating a. Adductor hiatus Adductor brevis Femoral a. 3rd perforating a. Popliteal a. Popliteal a. passing through adductor hiatus Anterior tibial a. Posterior tibial a. Interosseous membrane Fibular a. Clinical box 34.1 Femoral head necrosis Dislocation or fracture of the femoral head (e.g., in patients with osteoporosis) may tear the femoral neck vessels, resulting in femoral head necrosis. Dorsal pedal a. Medial plantar a. Fig. 34.4 Arteries of the femoral head Acetabular roof Anterior view. Head of femur Lig. of head of femur Femoral neck vessels Fibrous membrane Acetabu­ lar fossa Synovial membrane Lig. of head of femur A. of lig. of head of femur Synovial membrane Fibrous membrane Acetabular labrum Obturator a. Medial circum­ flex femoral a. Zona orbicularis Iliopsoas tendon Deep a. of the thigh Lateral circumflex femoral a. Medial circumflex femoral a. Lesser trochanter A Right femur. B Right femur, coronal section. 473 Lower Limb Veins & Lymphatics of the Lower Limb Fig. 34.5 Superficial (epifascial) veins of the lower limb Superficial circumflex iliac v. Femoral v. (in saphenous opening) Anterior femoral cutaneous v. Superficial epigastric v. Fig. 34.6 Deep veins of the lower limb External pudendal vv. Inguinal lig. Accessory saphenous v. Great saphenous v. Piriformis External iliac v. Lateral circumflex femoral vv. Medial circumflex femoral vv. Deep v. of thigh Great saphenous v. Femoral v. Accessory saphenous v. Posterior tibial vv. Adductor canal Adductor hiatus Popliteal v. Dorsal venous network Popliteal v. Dorsal venous arch Anterior tibial v. Fibular vv. Small saphenous v. Adductor magnus Lateral malleolus Genicular vv. A Right limb, anterior view. Small saphenous v. Great saphenous v. B Right limb, posterior view. Fig. 34.7 Veins of the sole of the foot Right foot, plantar view. Femoro­ popliteal v. Anterior tibial vv. Popliteal v. Great saphenous v. Small saphenous v. Posterior arch v. Small saphenous v. Dorsal venous network of the foot A Right limb, anterior view. B Right limb, posterior view. 474 Plantar digital vv. Plantar metatarsal vv. Plantar venous arch Lateral plantar v. Small saphenous v. Dorsal venous arch Medial plantar v. Great saphenous v. Posterior tibial vv. Fig. 34.8 Clinically important ­perforating veins Fig. 34.9 Superficial lymph nodes Right limb. Arrows indicate the main directions of lymphatic drainage. Right leg, medial view. 34 Neurovasculature Anus Superficial inguinal l.n. External iliac v. Great saphenous v. Scrotum Femoral v. Antero­ medial bundle Superficial popliteal l.n. Great saphenous v. Dodd’s vv. Small saphenous v. Femoral v. Great saphenous v. A Anterior view. Postero­ lateral bundle B Posterior view. Boyd’s vv. Lumbar lymph nodes Common iliac lymph nodes Inferior vena cava Posterior tibial vv. Posterior arch v. Cockett’s vv. • Receive drainage from – Deep inguinal l.n. – Urinary bladder, shaft and glans of penis, uterus Internal iliac lymph nodes Superolateral l.n. Superomedial l.n. Inferior l.n. Internal iliac v. Superficial inguinal lymph nodes Inguinal lig. • Receive drainage from – Skin of the limb (except the calf and the medial border of the foot) – Abdominal wall below the umbilicus – Lower back – Gluteal region, bowel, anal region – External genitalia (in women, also the uterine fundus along the round lig.) Fig. 34.10 Lymph nodes and ­lymphatic drainage Right limb, anterior view. Arrows indicate direction of lymphatic drainage. Yellow shading: superficial nodes; green shading: deep nodes. Common iliac v. External iliac v. External iliac lymph nodes Great saphenous v. • Receive drainage from – Pelvic organs – Pelvic wall – Gluteal muscles – Erectile tissues – Deep perineal region Deep inguinal lymph nodes • Receive drainage from – Deep portions of the lower limb Femoral v. Deep popliteal lymph nodes Superficial popliteal lymph nodes • Receive drainage from – Leg – Foot • Receive drainage from – Lateral border of foot – Calf Popliteal v. Small saphenous v. 475 Lower Limb Lumbosacral Plexus The lumbosacral plexus supplies sensory and motor innervation to the lower limb. It is formed by the anterior (ventral) rami of the lumbar and sacral spinal nerves, with contributions from the subcostal nerve (T12) and coccygeal nerve (Co1). The lumbar plexus mainly supplies the anterior and medial parts of the thigh with a small contribution to the medial leg. The sacral plexus supplies the posterior thigh and most of the leg and foot. Subcostal n. Iliohypogastric n. Ilioinguinal n. Genitofemoral n. Pudendal n. Inferior clunial nn. Nerves of the lumbosacral plexus Table 34.1 Lumbar plexus Iliohypogastric n. L1 Ilioinguinal n. L1 Obturator n. Genitofemoral n. L1–L2 Lateral cutaneous n. of the thigh Lateral cutaneous n. of the thigh L2–L3 Femoral n. Obturator n. L2–L4 Femoral n. p. 479 p. 480 p. 481 Sacral plexus Posterior cutaneous n. of the thigh Saphenous n. Sciatic n. Superior gluteal n. L4–S1 Inferior gluteal n. L5–S2 Posterior cutaneous n. of the thigh S1–S3 p. 482 Common fibular n. L4–S2 p. 484 Tibial n. L4–S3 p. 485 S2–S4 pp. 284–285 Sciatic n. Pudendal n. p. 483 Tibial n. Common fibular n. Deep fibular n. Tibial n. Superficial fibular n. Sural n. Medial and lateral plantar nn. 476 Lateral sural cutaneous n. (with communicating br.) Clinical box 34.2 Injuries to nerves of the lumbar and sacral plexuses Similar to nerve injuries of the upper limb, injuries involving nerves of the lumbosacral plexus are best understood though an appreciation of the plexus organization. The lumbar plexus arises from higher levels (L1–L4) of the spinal cord and supplies muscles of the abdominal wall and anterior and medial thigh. The sacral plexus arises from lower levels (L4–S4) of the spinal cord and supplies the perineum and, via the large sciatic nerve, the posterior thigh, entire leg and most of the foot. Nerves of the lumbar and sacral plexuses are less likely to be injured at the root level than those of the brachial plexus, although exceptions to this are the obturator and femoral nerves that may be compromised by herniation of intervertebral disks at L4 or L5 as they pass through the intervertebral foramina. Peripheral nerve injuries, such as that of the common fibular nerve, can occur in places where the nerve is superficial and passes close to a bony prominence. Fig. 34.11 Lumbosacral plexus L1 L2 Iliohypo­ gastric n. Ilioinguinal n. Lumbar plexus L3 L4 Genito­ femoral n. Lateral cutaneous n. of the thigh 34 Neurovasculature Right side, anterior view. Spinal nerve contributions to nerves of the lumbar and sacral plexuses. Separation of the anterior rami into anterior and posterior divisions are not as neatly demarcated in the lumbosacral plexus as they are in the brachial plexus of the upper limb. Where clearly separated into nerves they are indicated as: green = anterior ­division, blue = posterior divi­ sion. Note: Nerves of the sacral plexus not shown: n. to piriformis (S1, S2), n. to obturator internus (L5, S1), and n. to quadratus femoris (L5, S1). L5 Obturator n. S1 Femoral n. T12 vertebra 12th rib S2 Superior gluteal n. Subcostal n. S3 Inferior gluteal n. S4 Sciatic n. Sacral plexus Ilioinguinal n. Co1 Common fibular n. Coccygeal n. Genito­ femoral n. L5 vertebra Coccygeal plexus Lumbosacral trunk Pudendal n. Structure of the lumbosacral plexus. A Iliohypogastric n. S5 Tibial n. Posterior cutaneous n. of the thigh L1 vertebra S1 vertebra Obturator n. Femoral n. Lateral cutaneous n. of the thigh Superior and inferior gluteal nn. Sciatic n. Coccygeal plexus, anococcygeal nn. Coccygeal n. Muscular brs. Femoral n. Anterior femoral cutaneous brs. Pudendal n. Inguinal lig. Muscular brs. Saphenous n. Anterior br. Posterior br. Obturator n. Muscular brs. B Course of the lumbosacral plexus. Distribution of anterior rami of lumbar (yellow/orange) and sacral (blue/green) spinal nerves to the gluteal region and lower limb. Sciatic n. (common fibular n. and tibial n.) 477 Lower Limb Nerves of the Lumbar Plexus Table 34.2 Nerves of the lumbar plexus Nerve Level Iliohypogastric n. L1 Innervated muscle Cutaneous branches Anterior and lateral cutaneous brs. Transversus abdominis and internal oblique (inferior portions) ♂: Anterior scrotal nn. ♀: Anterior labial nn. Ilioinguinal n. L1 Genitofemoral n. L1–L2 ♂: Cremaster (genital br.) Genital br. Femoral br. Lateral cutaneous n. of the thigh L2–L3 — lateral cutaneous n. of the thigh Obturator n. L2–L4 See p. 480 Femoral n. L2–L4 See p. 481 T12–L4 Psoas major Quadratus lumborum Iliacus Intertransversarii lumborum Short, direct muscular brs. — Fig. 34.12 Cutaneous innervation of the inguinal region Right male inguinal region, anterior view. Ilioinguinal n. Iliohypo­ gastric n. Genitofemoral n. Lateral cutaneous br. Anterior cutaneous br. Superficial inguinal ring Ilioinguinal n. Lateral cutaneous n. of the thigh Genital br. Femoral br. Genito­ femoral n. Anterior scrotal brs. Femoral n., anterior cutaneous brs. Clinical box 34.3 Entrapment of the lateral femoral cutaneous nerve (meralgia paresthetica) Ischemia (diminished blood flow) of the lateral cutaneous nerve of the thigh can result when the nerve is stretched or entrapped by the inguinal ligament (see Fig. 34.11B) during hyperextension of the hip or with increased lordosis (curvature) of the lumbar spine, as often occurs during pregnancy. 478 This results in pain, numbness, or paresthesia (tingling or burning) on the outer aspect of the thigh. It is most commonly found in obese or diabetic individuals and in pregnant women. Fig. 34.13 Nerves of the lumbar plexus Right side, anterior view with the anterior abdominal wall removed. Internal oblique External oblique Iliac crest Lateral cutaneous br. Inguinal lig. Transversus abdominis Quadratus lumborum Iliohypogastric n. Internal oblique Anterior cutane­ ous br. Superficial inguinal ring Ilioinguinal n. Psoas major Psoas major Iliacus Quadratus lumborum 34 Neurovasculature Transversus abdominis Iliacus Inguinal lig. Ilioinguinal n. Superficial inguinal ring Spermatic cord B Ilioinguinal nerve. A Iliohypogastric nerve. Quadratus lumborum Quadratus lumborum Genitofemoral n. Psoas major Psoas major Anterior superior iliac spine Lateral cutaneous n. of the thigh Iliacus Inguinal lig. Rectus abdominis Inguinal lig. Femoral br. Iliacus Genital br. Fascia lata Spermatic cord Spermatic cord C Genitofemoral nerve. DLateral cutaneous nerve of the thigh. 479 Nerves of the Lumbar Plexus: Obturator & Femoral Nerves Lower Limb Fig. 34.15 Obturator nerve Right side, anterior view. Fig. 34.14 Obturator nerve: Cutaneous distribution L4 vertebra Right leg, medial view. Cutaneous br. Obturator n. Linea terminalis Pectineus Obturator externus Anterior br. Posterior br. Adductor brevis Muscular brs. Adductor longus Adductor magnus Cutaneous br. Gracilis Table 34.3 Obturator nerve (L2–L4) Motor branches Innervated muscles Direct br. Obturator externus Adductor longus Anterior br. Adductor brevis Gracilis Pectineus Posterior br. Sensory branches Cutaneous br. 480 Adductor magnus Fig. 34.16 Femoral nerve Right side, anterior view. L4 vertebra Fig. 34.17 Femoral nerve: Cutaneous distribution Right limb, anterior view. 34 Neurovasculature Psoas major Muscular br. Iliacus Inguinal lig. Iliopsoas Sartorius Anterior cutaneous brs. Femoral n. Muscular brs. Anterior cutaneous brs. Rectus femoris Infra­ patellar br. Pectineus Saphenous n. Medial cutaneous brs. Muscular brs. Saphenous n. Vastus intermedius Quadriceps femoris Vastus lateralis Rectus femoris Vastus medialis Anteromedial intermuscular septum Sartorius Table 34.4 Femoral nerve (L2–L4) Motor branches Innervated muscles Iliopsoas Infrapatellar br. Saphenous n. Muscular brs. Pectineus Sartorius Quadriceps femoris Sensory branches Anterior cutaneous br. Saphenous n. 481 Lower Limb Nerves of the Sacral Plexus Nerves of the sacral plexus Table 34.5 Nerve Level Innervated muscle Cutaneous branches Superior gluteal n. L4–S1 Gluteus medius Gluteus minimus Tensor fasciae latae — Inferior gluteal n. L5–S2 Gluteus maximus — Posterior cutaneous n. of the thigh S1–S3 — Posterior cutaneous n. of the thigh S1–S2 Piriformis — L5–S1 Obturator internus Gemelli — Quadratus femoris — N. of piriformis Direct branches N. of obturator internus N. of quadratus femoris Sciatic n. Common fibular n. L4–S2 See p. 484 Tibial n. L4–S3 See p. 485 S2–S4 See pp. 284–285 Pudenal n. Inferior clunial nn. Perineal brs. Fig. 34.18 Cutaneous innervation of the gluteal region Right limb, posterior view. Fig. 34.19 Posterior cutaneous nerve of the thigh: Cutaneous distribution Right limb, posterior view. Superior clunial nn. (posterior rami of L1–L3) Middle clunial nn. (posterior rami of S1–S3) Lateral br. (iliohypogastric n.) Inferior clunial nn. Inferior clunial nn. (Posterior cutaneous n. of the thigh) Perineal brs. Posterior cutaneous n. of the thigh Fig. 34.20 Emerging spinal nerve Horizontal section, superior view. Anterior (ventral) root Anterior sacral foramen Anterior (ventral) ramus (to sacral plexus) Posterior (dorsal) ramus Cauda equina 482 Posterior (dorsal) root Posterior sacral foramen Lateral br. (to the clunial nn.) Small gluteal muscle weakness The small gluteal muscles on the stance side stabilize the pelvis in the coronal plane (A). Weakness or paralysis of the small gluteal muscles from damage to the superior gluteal nerve (e.g., due to a faulty intramuscular injection) is manifested by weak abduction of the affected hip joint. In a positive Trendelenburg’s test, the pelvis sags toward the normal, unsupported side (B). Tilting the upper body toward the affected side shifts the center of gravity onto the stance side, thereby elevating the pelvis on the swing side (Duchenne’s limp) (C). With bilateral loss of the small gluteals, the patient exhibits a typical waddling gait. Fig. 34.21 Nerves of the sacral plexus Right limb. Gluteus medius Superior gluteal n. 34 Neurovasculature Clinical box 34.4 Insufficient small gluteals Gluteus medius and minimus Anterior superior iliac spine Shifted center of gravity Pelvis sags Tensor fasciae latae Iliotibial tract Stance leg Swing leg Normal gait. A B Small gluteal muscle weakness. C Duchenne’s limp. A Superior gluteal nerve. Lateral view. Piriformis (with n.) Inferior gluteal n. Gluteus maximus Muscular brs. Sciatic n. Inferior gluteal nerve. Posterior view. B Obturator internus (with n.) Sacrotuberous lig. Sciatic n. Gemellus superior Gemellus inferior Quadratus femoris (with n.) Direct branches. Posterior view. C 483 Lower Limb Nerves of the Sacral Plexus: Sciatic Nerve The sciatic nerve gives off several direct muscular branches before dividing into the tibial and common fibular nerves proximal to the popliteal fossa. Fig. 34.23 Common fibular nerve Fig. 34.22 Common fibular nerve: Cutaneous distribution Right limb, lateral view. Anterior superior iliac spine Lateral sural cutaneous n. Sciatic n. Fibular communicating br. Medial dorsal cutaneous n. Medial dorsal cutaneous n. Intermediate dorsal cutaneous n. Intermediate dorsal cuta­ neous n. Lateral cutaneous n. of big toe Deep fibular n. Medial cutaneous n. of 2nd toe A Right leg, anterior view. Table 34.6 Superficial fibular n. Tibial n. Common fibular n. B Right leg, lateral view. Common fibular nerve (L4–S2) Nerve Innervated muscles Sensory branches Direct branches from sciatic n. Bicep femoris (short head) — Superficial fibular n. Fibularis brevis and longus Medial dorsal cutaneous n. Intermediate dorsal cutaneous n. Deep fibular n. Tibialis anterior Extensors digitorum brevis and longus Extensors hallucis brevis and longus Fibularis tertius Lateral cutaneous n. of big toe Medial cutaneous n. of 2nd toe Biceps femoris, long head Neck of fibula Head of fibula Deep fibular n. Superficial fibular n. Tibialis anterior Fibularis longus Extensor digitorum longus Fibularis brevis Extensor hallucis longus Lateral malleolus 484 Biceps femoris, short head Superficial fibular n. Medial dorsal cutaneous n. Intermediate dorsal cuta­ neous n. Fig. 34.24 Tibial nerve Fig. 34.25 Tibial nerve: Cutaneous distribution Right limb. Right lower limb, posterior view. 34 Neurovasculature Proper plantar digital nn. Lumbricals Adductor hallucis Common plantar digital nn. Flexor hallucis longus tendon Lateral plantar n., super­ ficial br. Muscular brs. Abductor digiti minimi Flexor digitorum longus tendon Lateral plantar n. Fibular com­ municating br. Sural n. Abductor hallucis Quadratus plantae Sciatic n. Medial sural cutaneous n. Medial plantar n. Flexor digitorum brevis and plantar aponeurosis Sacro­ tuberous lig. Lateral dorsal cutaneous n. Medial calcaneal brs. Lateral calcaneal brs. Proper plantar digital nn. Tibial n. Muscular brs. Biceps femoris, long head Semi­ tendinosus Semi­ membranosus Adductor magnus, medial part Biceps femoris, short head B Right foot, plantar view. Table 34.7 Nerve Innervated muscles Sensory branches Direct brs. from sciatic n. Semitendinosus Semimembranosus Biceps femoris (long head) Adductor magnus (medial part) — Tibial n. Triceps surae Plantaris Popliteus Tibialis posterior Flexor digitorum longus Flexor hallucis longus Medial sural cutaneous n. Medial and lateral calcaneal brs. Lateral dorsal cutaneous n. Medial plantar n. Adductor hallucis Flexor digitorum brevis Flexor hallucis brevis (medial head) 1st lumbricals Proper plantar digital nn. Lateral plantar n. Flexor hallucis brevis (lateral head) Quadratus plantae Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi 2nd to 4th lumbricals 1st to 3rd plantar interossei 1st to 4th dorsal interossei Adductor hallucis Proper plantar digital nn. Tibial n. Popliteal fossa Gastrocnemius Soleus Deep flexors Deep flexor tendons Tibial n. (in malleolar canal) A Posterior view. Lateral malleolus Tibial nerve (L4–S3) 485 Lower Limb Superficial Nerves & Veins of the Lower Limb Fig. 34.26 Superficial cutaneous veins and nerves of right lower limb Inguinal lig. Superficial circumflex iliac v. Lateral cutaneous n. of the thigh Superficial epigastric v. Femoral a. and v. (in saphenous opening) Ilioinguinal n. Superior clunial nn. Iliohypogastric n., lateral cutaneous br. Middle clunial nn. Superficial inguinal ring External pudendal vv. Femoral n., anterior femoral cutaneous brs. Accessory saphenous v. Inferior clunial nn. (posterior cutaneous n. of the thigh) Lateral cutaneous n. of the thigh Fascia lata Great saphenous v. Obturator n. Posterior cutaneous n. of the thigh Obturator n., cutaneous br. Saphenous n., infrapatellar br. Saphenous n. (femoral n.) Lateral sural cutaneous n. (common fibular n.) Great saphenous v. Saphenous n. (femoral n.) Small saphenous v. Superficial fibular n. Medial sural cutaneous n. (tibial n.) Lateral sural cutaneous n. (common fibular n.) Sural n. (tibial n.) Intermediate dorsal cutaneous n. Sural n. (tibial n.) Medial dorsal cutaneous n. Calcaneal brs. Lateral dorsal cutaneous n. (tibial n.) Deep fibular n. Medial and lateral plantar cutaneous brs. A Anterior view. 486 B Posterior view. Right lower limb. Iliohypo­ gastric n. Lateral cutaneous n. of the thigh Obturator n. Genitofemoral n. Iliohypogastric n. Clunial nn. Ilioinguinal n. 34 Neurovasculature Fig. 34.27 Cutaneous innervation of the lower limb Lateral cutaneous n. of the thigh Posterior cutaneous n. of the thigh Femoral n. Obturator n. Common fibular n. Sciatic n. Femoral n. Tibial n. Common fibular n. Sciatic n. Tibial n. B Posterior view. Anterior view. A Fig. 34.28 Dermatomes of the lower limb Right lower limb. T11 L2 T12 L1 L3 S2 S5 L2 S4 L3 S3 L4 L5 S2 S1 L4 L5 L4 S1 Anterior view. A L5 Posterior view. B 487 Lower Limb Topography of the Inguinal Region Fig. 34.29 Superficial veins and lymph nodes Right male inguinal region, anterior view. Removed: Cribriform fascia over the saphenous opening. Superficial and superolateral inguinal l.n. Inguinal lig. External iliac v. External iliac l.n. Superficial circum­ flex iliac v. Rosenmüller’s l.n. Superficial epigastric v. External pudendal v. Superficial and superomedial inguinal l.n. Saphenous opening Femoral a. and v. Deep inguinal l.n. Anterior femoral cutaneous v. Superficial and inferior inguinal l.n. Great saphenous v. Fig. 34.30 Inguinal region Right male inguinal region, anterior view. Linea alba External oblique Arcuate line Internal oblique Rectus abdominis Transversus abdominis Lateral cutaneous n. of the thigh Anterior rectus sheath Superficial circumflex iliac a. and v. Inguinal lig. Superficial abdominal fascia Genitofemoral n., femoral br. External oblique aponeurosis Superficial inguinal ring Ilioinguinal n. Genitofemoral n., genital br. Reflected inguinal lig. Spermatic cord (cut) Femoral a. and v. (deep to saphenous opening) Lacunar lig. Saphenous opening in fascia lata External pudendal a. and v. Anterior femoral cutaneous v. 488 Great saphenous v. Pectineus, deep to fascia lata Region Anterior superior iliac spine Structures in the inguinal region Boundaries Contents Retro-inguinal space ① ② Iliopectineal arch ③ Reflected inguinal lig. Iliopubic eminence Pubic tubercle Lacunar lig. ① Muscular compartment Anterior superior iliac spine Inguinal lig. Iliopectineal arch Femoral n. Lateral cutaneous n. of the thigh Iliacus Psoas major ②V ascular compartment Inguinal lig. Iliopectineal arch Lacunar lig. Femoral a. and v. Genitofemoral n., femoral br. Rosenmüller’s lymph node Medial crus Lateral crus Reflected inguinal lig. Ilioinguinal n. Genitofemoral n., genital br. Spermatic cord 34 Neurovasculature Table 34.8 Ilioinguinal lig. Inguinal canal ③ Superficial inguinal ring Fig. 34.31 Retro-inguinal space: Muscular and vascular compartments Right inguinal region, anterior view. External oblique Lateral cutaneous n. of the thigh External oblique aponeurosis Inguinal lig. Muscular compartment Femoral n. Iliacus Iliopsoas Intercrural fibers Psoas major Medial crus Iliopectineal bursa Lateral crus Superficial inguinal ring Iliopectineal arch Reflected inguinal lig. Acetabular fossa Femoral ring Lacunar lig. Genitofemoral n., femoral br. Vascular compartment Pubic symphysis Femoral a. and v. Rosenmüller’s l.n. Ischial spine Ischial tuberosity 489 Lower Limb Topography of the Gluteal Region Fig. 34.32 Gluteal region Right gluteal region, posterior view. Gluteal fascia (gluteus medius) Gluteal fascia (gluteus maximus) Gluteus maximus Gluteus medius Superior gluteal a., v., and n. Inferior gluteal a., v., and n. Gluteal sulcus Fascia lata A Fasciae and cutaneous neurovasculature. Posterior cutaneous n. of the thigh Pudendal n., perineal brs. Obturator internus Sacrotuberous lig. Ischial tuberosity Posterior cutaneous n. of the thigh, perineal brs. Superior clunial nn. Iliohypogastric n., lateral br. Gluteal fascia (gluteus medius) Middle clunial nn. Gluteus maximus Inferior clunial nn. Adductor magnus Posterior cutaneous n. of the thigh (with biceps femoris long head) Semi­ membranosus Semitendinosus B Gluteal region. Removed: Fascia lata. 490 Piriformis Gemellus superior and inferior Obturator internus Sciatic n. (with a.) Quadratus femoris Gluteus maximus Adductor magnus Adductor magnus Gracilis Posterior cutaneous n. of the thigh C Deep gluteal region. Partially removed: Gluteus maximus. Table 34.9 Sciatic foramina Posterior superior iliac spine Anterior superior iliac spine A Piriformis Greater sciatic foramen ① Suprapiriform portion Superior gluteal a., v., and n. ② Infrapiriform portion Inferior gluteal a., v., and n. Internal pudendal a. and v. Pudendal n. Sciatic n. Posterior cutaneous n. of the thigh S Sacro­ spinous lig. Sacro­ tuberous lig. Greater sciatic notch D ③ Lesser sciatic foramen Internal pudendal a. and v. Pudendal n. Obturator internus Boundaries Greater sciatic notch Sacrospinous lig. Sacrum 34 Neurovasculature Transmitted structures Foramen Lesser sciatic notch Sacrospinous lig. Sacrotuberous lig. Lesser sciatic notch Fig. 34.33 Gluteal region and ­ischioanal fossa Right gluteal region, posterior view. Removed: Gluteus maximus and medius. Anterior superior iliac spine Gluteus minimus Posterior superior iliac spine Tensor fasciae latae Superior gluteal a. and n. Piriformis Inferior gluteal n. Gemellus superior Inferior gluteal aa. and vv. Obturator internus Pudendal n. Gemellus inferior Internal pudendal a. and v. Br. of medial circumflex femoral a. Obturator internus Trochanteric bursa Pudendal (Alcock’s) canal Quadratus femoris Sacrotuberous lig. Adductor magnus Sciatic n. Gracilis Adductor magnus 1st perforating a. Semitendinosus Semi­ membranosus Biceps femoris, long head Posterior cutaneous n. of the thigh 491 Topography of the Anterior, Medial & Posterior Thigh Fig. 34.34 Anterior and medial thigh Lower Limb Anterior superior Inguinal Superficial epigastric a. iliac spine lig. Right thigh, anterior view. Superficial circumflex iliac a. External oblique aponeurosis Tensor fasciae latae Iliopsoas Femoral n. External pudendal a. Femoral a. and v. Spermatic cord Pectineus Deep a. of thigh Sartorius Adductor longus Gracilis Rectus femoris External iliac a. and v. Inguinal lig. Lateral cutaneous n. of the thigh Sartorius Iliotibial tract Femoral a. and v. in adductor canal Femoral n. Sacral plexus Femoral a. and v. Rectus femoris Lateral circumflex femoral a., ascending br. Deep a. of thigh Quadriceps femoris Superior and inferior gluteal aa. Medial circumflex femoral a. Pectineus Obturator n. Adductor brevis Perforating aa. Lateral circumflex femoral a., descending br. Fascia lata Adductor longus Adductor magnus Patellar vascular network Descending genicular a. A Femoral triangle. Removed: Skin, subcutaneous tissue, and fascia lata. Partially transparent: Sartorius. Vastus intermedius Rectus femoris Vastus medialis Vastus lateralis Femoral a. and v., saphenous n. (in adductor canal) Obturator n., cutaneous br. Sartorius Saphenous n. B Neurovasculature of the anterior thigh. Removed: Anterior abdominal wall. Partially removed: Sartorius, rectus femoris, adductor longus, and pectineus. 492 34 Neurovasculature Fig. 34.35 Posterior thigh Right thigh, posterior view. Superior clunial nn. Iliohypo­ gastric n., lateral br. Gluteal fascia (gluteus medius) Middle clunial nn. Gluteus maximus Inferior clunial nn. Adductor magnus Posterior cutaneous n. of the thigh Fascia lata, iliotibial tract Gluteus maximus Gluteus medius Superior gluteal a., v., and n. Gluteus minimus Inferior gluteal n. Piriformis Pudendal n. Medial circumflex femoral a. Inferior gluteal a. Trochanteric bursa Sacrotuberous lig. Gluteus maximus Posterior cutaneous n. of the thigh Quadratus femoris Sciatic n. (with a.) Obturator internus 1st perforating a. Adductor magnus Biceps femoris, long head Biceps femoris, long head Adductor magnus 2nd perforating a. Popliteal a. and v. Tibial n. Common fibular n. Lateral sural cutaneous n. Sural n. Gracilis Semi­ tendinosus 3rd perforating a. Adductor hiatus Biceps femoris, short head Iliotibial tract Popliteal a. and v. Common fibular n. Semi­ membranosus Gluteal region and thigh. Removed: Fascia lata. A Biceps femoris, long head Tibial n. Plantaris Medial sural cutaneous n. Lateral sural cutaneous n. Gastrocnemius Neurovasculature of the posterior thigh. Partially removed: Gluteus maxi­ B mus, gluteus medius, and biceps femoris. Retracted: Semimembranosus. 493 Lower Limb Topography of the Posterior Compartment of the Leg & Foot Fig. 34.36 Posterior compartment of leg Right leg, posterior view. Semi­ tendinosus Semi­ membranosus Tibial n. Semi­ tendinosus Biceps femoris Plantaris Common fibular n. Gracilis Semi­ membranosus Tibial n. Gastroc­ nemius Lateral sural cutaneous n. Plantaris Common fibular n. Popliteus Popliteal a. and v. Medial sural cutaneous n. Great saphenous v. Biceps femoris Tendinous arch of soleus Soleus Gastrocnemius, lateral head Deep fascia of the leg Small saphenous v. Gastrocnemius, medial head Communi­ cating br. Posterior tibial a. Tibial n. Fibular a. Flexor digitorum longus Tibialis posterior Saphenous n. Sural n. Flexor hallucis longus Medial malleolus Fibularis brevis Perforating br. Communi­ cating br. Fibular a. Fibularis longus Lateral malleolus Tibial n., medial calcaneal br. A Superficial neurovascular structures. 494 Dorsal cutaneous n. of the foot Flexor retinaculum Calcaneal (Achilles’) tendon Calcaneal rete B Deep neurovascular structures. Removed: Gastrocnemius. Windowed: Soleus. Fig. 34.37 Popliteal region Right leg, posterior view. Sciatic n. Biceps femoris, long head Gracilis Biceps femoris, short head Semi­ membranosus Semi­ tendinosus Deep popliteal l. n. Popliteal a. and v. Common fibular n. Gastrocnemius, medial head Biceps femoris Semi­ membranosus Plantaris Gastroc­ nemius Small saphenous v. Medial superior genicular a. Medial subtendinous bursa of gastrocnemius 34 Neurovasculature Popliteal a. and v. Lateral superior genicular a. Plantaris Middle genicular a. Gastroc­ nemius, lateral head Semimembranosus bursa Oblique popliteal lig. Lateral inferior genicular a. Semimembranosus tendon Posterior tibial recurrent a. Medial inferior genicular a. B Deep lymph nodes. Fig. 34.38 Ankle region Right ankle, medial view. Plantaris tendon Fibularis group Tibial n. Fibula Deep flexors Superficial flexors Extensor group Soleus Popliteus Gastrocnemius Tibia Triceps surae A Deep neurovascular structures. Tibial n., posterior tibial a. Superior extensor retinaculum Medial malleolar brs. Medial malleolus (with subcutaneous bursa) Tibialis posterior Inferior extensor retinaculum Flexor digi­ torum longus Tibialis anterior Flexor hallucis longus Medial tarsal aa. Calcaneal (Achilles’) tendon Extensor hallucis longus tendon Medial calcaneal br. Medial plantar a., superficial br. Tarsal tunnel Flexor retinaculum Medial plantar a. and n. 1st metatarsal Abductor hallucis Medial plantar a. and n. Lateral plantar a. and n. 495 Lower Limb Topography of the Lateral & Anterior Compartments of the Leg & Dorsum of the Foot Head of fibula Fig. 34.39 Neurovasculature of the lateral compartment of the leg Right limb. Removed: Origins of the fibularis longus and extensor digitorum longus. Biceps femoris Short head Tibia Anterior intermuscular septum Superficial fibular n. Iliotibial tract Long head Common fibular n. Lateral sural cutaneous n. Transverse intermuscular septum Anterior crural intermuscular septum Table 34.10 Deep fibular n. Compartment ① Anterior compartment ③ Superficial part Sural n. Posterior compartment 496 Extensor hallucis longus Fibularis longus Fibularis brevis Triceps surae (gastrocnemius and soleus) Neurovascular contents Deep fibular n. Anterior tibial a. and v. Intermediate dorsal cutaneous n. Deep fibular n., cutaneous br. Superficial fibular n. — Plantaris Flexor digitorum longus Flexor hallucis longus Deep fascia of the leg Lateral dorsal cutaneous n. Extensor digitorum longus Tibialis posterior ④ Deep part Superficial fibular n. Lateral malleolus Deep fascia of the leg Fibularis tertius Extensor digitorum longus Medial dorsal cutaneous n. Sural n., small saphenous v. Muscular contents ② Lateral compartment Soleus Tibial n., posterior tibial a. and v. Compartments of the leg Tibialis anterior Commu­ nicating br. F Tibialis anterior Fibularis longus Medial sural cutaneous n. (tibial n.) Saphenous n., great saphenous v. Interosseous membrane D Fibular a. and v. Superficial fibular n. Gastroc­ nemius Lateral calcaneal brs. S Posterior intermuscular septum Lateral tibial condyle Head of fibula A Fibula Patella Deep fibular n., anterior tibial a. and v. Tibial n. Posterior tibial a. and v. Fibular a. and v. Fig. 34.40 Neurovasculature of the anterior compartment of the leg and foot Clinical box 34.5 Right limb with foot in plantar flexion. Muscle edema or hematoma can lead to a rise in tissue fluid pressure in the compartments of the leg. Subsequent compression of neurovascular structures due to this increased pressure may cause ischemia and irreversible muscle and nerve damage. Patients with anterior compartment syndrome, the most common form, suffer excruciating pain and cannot dorsiflex the toes. Emergency incision of the fascia of the leg may be performed to relieve compression. Patella Head of fibula Patellar lig. Pes anserinus (common insertion of sartorius, gracilis, and semitendinosus) 34 Neurovasculature Compartment syndrome Gastrocnemius Fibularis longus Fibula Tibia Fibular a., perforating br. Extensor hallucis longus Anterior lateral malleolar a. Tibialis anterior tendon Deep fibular n. Lateral br. of deep fibular n. Extensor hallucis brevis Extensor digitorum brevis Lateral tarsal a. Medial br. of deep fibular n. Dorsalis pedis a. Arcuate a. Dorsal interossei Deep plantar a. Dorsal meta­ tarsal aa. Extensors hallucis longus and brevis tendons Extensors digitorum longus and brevis tendons Dorsal digital nn. Muscular brs. Deep fibular n. Extensor hallucis longus Extensor digitorum longus Anterior tibial a. Tibialis anterior Anterior tibial a. and v. Soleus Superficial fibular n. Fibularis brevis Inferior extensor retinaculum Lateral dorsal cutaneous n. Intermediate dorsal cutaneous n. Medial dorsal cutaneous n. Dorsal metatarsal aa. Superior extensor retinaculum Medial malleolus Dorsalis pedis a. Extensor hallucis brevis Extensor hallucis longus tendon Deep fibular n. Deep fibular n., cutaneous br. B Neurovasculature of the leg. Removed: Skin, subcutaneous tissue, and fasciae. Retracted: Tibialis anterior and extensor hallucis longus. Dorsal digital aa. A Neurovasculature of the dorsum of the foot. 497 Lower Limb Topography of the Sole of the Foot Fig. 34.41 Neurovasculature of the sole of the foot Right foot, plantar view. Proper plantar digital aa. Proper plantar digital nn. Common plantar digital nn. Medial plantar n. Lateral plantar a. Medial plantar a., super­ ficial br. Plantar aponeurosis Lateral plantar n., superficial brs. Lateral plantar sulcus Medial plantar a., deep br. Medial plantar n., super­ ficial br. Medial plantar sulcus Abductor hallucis Proper plantar digital aa. and nn. Flexor digi­ torum brevis tendons Plantar metatarsal aa. Lateral plantar n., super­ ficial br. A Superficial layer. Removed: Skin, subcutane­ ous tissue, and fascia. Lateral plantar n., deep br. Quadratus plantae Lateral plantar a., v., and n. Abductor digiti minimi Flexor digitorum brevis B Middle layer. Removed: Plantar aponeurosis and flexor digitorum brevis. 498 Flexor hallucis longus tendon Common plantar digital nn. Medial plantar a., super­ ficial br. Medial plantar a., deep br. Flexor digi­ torum longus tendon Medial plantar n. Abductor hallucis Plantar aponeurosis 34 Neurovasculature Proper plantar digital aa. and nn. Flexor digitorum longus tendons Flexor digitorum brevis tendons Lumbricals Transverse head Plantar interossei Adductor hallucis Oblique head Plantar metatarsal aa. Flexor hallucis brevis Deep plantar arch Medial plantar a., deep br. Lateral plantar n., deep br. Flexor hallucis longus tendon Quadratus plantae Medial plantar a. Medial plantar n. Lateral plantar a., v., and n. Abductor hallucis Flexor digitorum brevis Plantar aponeurosis C Deep layer. Removed: Flexor digitorum longus. Windowed: Adductor hallucis (oblique head). Extensor digitorum longus Fig. 34.42 Neurovasculature of the foot: Cross section Coronal section, distal view. Intermediate dorsal cuta­ Extensor neous n. digitorum longus Interossei 3rd metatarsal Deep fibular n., dorsal pedal a. Extensor hallucis brevis Extensor digitorum longus Extensor hallucis longus Lateral dorsal cutaneous n. Medial dorsal cutaneous n. Dorsal meta­ tarsal a. 2nd metatarsal Medial cuneiform Abductor digiti minimi Tibialis anterior Opponens digiti minimi Deep layer of plantar fascia Flexor digiti minimi brevis Saphenous n., cutaneous br. Lateral plantar a. and v. Abductor hallucis Lateral plantar septum Lateral plantar n., deep br. Lateral plantar n., superficial br. Quadratus plantae Fibularis longus Aponeurosis of flexor digitorum longus Flexor hallucis brevis Plantar aponeurosis Flexor digitorum brevis Medial plantar a. and n. Deep plantar arch Flexor hallucis longus Medial plantar septum 499 35 Sectional & Radiographic Anatomy Lower Limb Sectional Anatomy of the Lower Limb Fig. 35.1 Windowed dissection of the thigh and leg Right limb, posterior view. Iliac crest Gluteus minimus Gluteus maximus Gluteus medius Piriformis Gemellus superior Tensor fasciae latae Obturator internus Gluteus maximus Gemellus inferior Quadratus femoris Ischial tuberosity Adductor magnus Gracilis Adductor magnus Iliotibial tract Semitendinosus Femur Biceps femoris, long head Rectus femoris Vastus medialis Vastus intermedius Sartorius Vastus lateralis Gracilis Adductor longus Biceps femoris, short head Adductor brevis Sciatic nerve Gracilis Semitendinosus Semimembranosus Iliotibial tract Biceps femoris, long head Plantaris Gastrocnemius Tibia Soleus Fibula Interosseous membrane Triceps surae Calcaneal (Achilles’) tendon 500 Right limb, proximal view. Quadriceps femoris Vastus medialis Vastus intermedius Rectus femoris Vastus lateralis Medial intermuscular septum Femur Sartorius Femoral artery and vein Iliotibial tract Adductor longus 35 Sectional & Radiographic Anatomy Fig. 35.2 Cross-section through the thigh and leg Sciatic nerve Adductor brevis Lateral intermuscular septum Gracilis Biceps femoris, short head Adductor magnus Semimembranosus Semitendinosus Biceps femoris, long head A Thigh (plane of upper section in Fig. 35.1A) Deep fibular nerve Tibialis anterior Extensor hallucis longus Extensor digitorum longus Tibia Anterior tibial artery and vein Anterior intermuscular septum Interosseous membrane Fibularis brevis Tibialis posterior Fibularis longus Flexor digitorum longus Posterior intermuscular septum Tibial nerve Fibula Plantaris tendon Soleus Posterior tibial artery and vein Transverse Flexor intermuscular hallucis longus septum Gastrocnemius, Gastrocnemius, lateral head medial head B Leg (plane of lower section in Fig. 35.1B) 501 Lower Limb Radiographic Anatomy of the Lower Limb (I) Fig. 35.3 MRI of the thigh Sartorius Transverse section, distal (inferior) view. Rectus femoris Circumflex femoral a. and v. Femoral a., v., and n. Adductor longus Deep femoral a. and v. Tensor fasciae latae A B C Pectineus Vastus lateralis Iliotibial tract Femur Adductor magnus Sciatic n. Lateral femoral intermuscular septum A Proximal thigh. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Gluteus maximus Rectus femoris Vastus lateralis Vastus medialis Sartorius Great saphenous v. Vastus intermedius Femoral a. and v. Femur Sciatic n. B Mid-thigh. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Biceps femoris, long head Adductor longus Gracilis Adductor magnus Semimembranous Semitendinous Rectus femoris, tendon Vastus intermedius Vastus medialis Femur Vastus lateralis Biceps femoris, short head Perforating a. and v. of deep a. and v. of thigh C Distal thigh. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) 502 Common fibular n. Tibial n. Biceps femoris, long head Sartorius Femoral a. and v. Gracilis Semimembranosus Semitendinosus Fig. 35.4 MRI of the leg Transverse section, distal (inferior) view. Tibia Tibial tuberosity Sartorius, tendon Extensor digitorum longus Gracilis, tendon A Semitendinosus, tendon B Popliteus Common fibular n. Popliteal a. and v. C Tibial n. Gastrocnemius, lateral head Gastrocnemius, medial head A Proximal leg. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Tibialis anterior Extensor halluces longus Tibia Extensor digitorum longus Tibialis posterior Deep fibular n. Flexor digitorum longus Anterior tibial a. and v. Posterior tibial a. and v. Interosseous membrane Tibial n. Fibularis brevis B Mid-leg. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) 35 Sectional & Radiographic Anatomy Anterior tibial muscle Fibular a. and v. Fibula Flexor hallucis longus Soleus Extensor hallucis longus Anterior tibial a. and v. Great saphenous v. Extensor digitorum longus Tibia Tibialis posterior, tendon Fibula Fibularis longus, tendon C Distal leg. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 2, 4th ed. New York, NY: Thieme; 2014.) Fibularis brevis Sural n. Small saphenous v. Tibial n. Flexor hallucis longus Soleus muscle Tendons of triceps surae and plantaris 503 Lower Limb Radiographic Anatomy of the Lower Limb (II) Fig. 35.5 Radiograph of the right hip joint Anteroposterior view. Anterior acetabular rim Roof of the acetabulum Posterior acetabular rim Fovea of the femoral head Femoral head Greater trochanter Köhler’s teardrop figure Femoral neck Superior pubic ramus Intertrochanteric crest Obturator foramen Ischial tuberosity Lesser trochanter Fig. 35.6 Radiograph of right hip joint with limb abducted laterally (Lauenstein view) (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Anterior superior iliac spine Sacroiliac joint Superior acetabular rim Anterior acetabular rim Femoral neck Pubic bone Greater trochanter Ischium Lesser trochanter Superior pubic ramus Inferior pubic ramus Femoral head 504 Ischial tuberosity Fig. 35.7 MRI of the right hip joint Sartorius Iliopsoas Tensor fascia lata Head of femur Gluteus medius Femoral a., v., and n. Urinary bladder Pubis, superior ramus Obturator a., v., and n. Levator ani Obturator internus Sciatic n. Ischium Gluteus maximus Fig. 35.8 MRI of the hip joints 35 Sectional & Radiographic Anatomy Transverse section, distal (inferior) view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) L4 vertebra Coronal section, anterior view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Psoas Iliacus Urinary bladder Gluteus medius Head of femur Iliotibial tract Hip joint Obturator internus Greater trochanter Obturator externus Gracilis Adductor longus Vastus lateralis Fig. 35.9 MRI of the right hip joint Sagittal section, medial view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Iliopsoas Ilium (roof of acetabulum) Gluteus maximus Hip joint Femur, head Lateral circumflex femoris a. (ascending branch) Pectineus Ischium Sartorius Deep a. and v. of the thigh Adductor magnus Biceps femoris Vastus medialis 505 Lower Limb Radiographic Anatomy of the Lower Limb (III) Fig. 35.10 Radiograph of the right knee joint Femur Anteroposterior view. (Reproduced courtesy of Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig Holstein, Campus Kiel: Prof. Dr. Med. S. Müller-Huelsbeck.) Patella Lateral femoral epicondyle Medial femoral epicondyle Medial femoral condyle Lateral femoral condyle Medial tibial condyle Lateral tibial condyle Medial and lateral tubercles of intercondylar eminence Epiphyseal plate Fibular head Tibia Fibula Cortex Fig. 35.11 Radiograph of the knee in flexion Patellofemoral joint (Reproduced courtesy of Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig Holstein, Campus Kiel: Prof. Dr. Med. S. Müller-Huelsbeck.) Patella Femur Patella Lateral femoral condyle Medial femoral condyle Tibial plateau Fibular head Tibial tuberosity Lateral femoral condyle A Lateral view. 506 B Sunrise view. Intercondylar fossa Medial femoral condyle Fig. 35.12 MRI of the knee joint Patellar lig. Lateral femoral condyle Medial collateral lig. Lateral collateral lig. Medial femoral condyle Anterior cruciate lig. Biceps femoris Posterior cruciate lig. Popliteal a. and v. Gastrocnemius, lateral head A Transverse section, distal (inferior) view. Gastrocnemius, medial head Tibial n. Anterior cruciate lig. Lateral epicondyle Posterior cruciate lig. Medial collateral lig. Lateral femoral condyle Medial femoral condyle Lateral meniscus, intermediate portion Medial meniscus, intermediate portion Lateral tibial condyle Fibula, head B Coronal section. 35 Sectional & Radiographic Anatomy (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Medial intercondylar tubercle Fig. 35.13 MRI of the knee joint Medial tibial condyle Quadriceps tendon Sagittal section. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Popliteal a. Popliteal v. Vastus lateralis Biceps femoris Patella Gastrocnemius, lateral head Femur, lateral condyle A B Lateral meniscus, posterior horn Anterior cruciate lig. Patellar lig. Tibiofibular joint Fibula, head A Lateral meniscus, anterior horn Lateral tibial condyle B Infrapatellar fat pad Posterior cruciate lig. 507 Lower Limb Radiographic Anatomy of the Lower Limb (IV) Fig. 35.14 Radiograph of the ankle (Reproduced from Moeller TB, Reif E. Taschenatlas der Roentgenanatomie, 2nd ed. Stuttgart: Thieme; 1998.) Fibula Tibia Tibia Fibula Growth plate Talocrural joint Medial malleolus Growth plate Fibular notch Talocrural joint Medial malleolus Lateral malleolus Trochlea of talus Calcaneus Subtalar joint Navicular A Anteroposterior view. Trochlea of talus Talus Lateral malleolus Talonavicular joint Sinus tarsi Navicular Posterior tuberosity of calcaneus Cuboid B Left lateral view. Fig. 35.15 Anterior-posterior view of the forefoot Distal phalanx Distal phalanx Middle phalanx Proximal phalanx Distal interphalangeal joint Proximal phalanx Proximal interphalangeal joint Metatarsophalangeal joint Sesamoids Metatarsals Lateral cuneiform Metatarsophalangeal joint Base of 5th metatarsal Cuboid Calcaneocuboid joint 508 Medial cuneiform Intermediate cuneiform Intertarsal joint Navicular Talocalcaneonavicular joint Fig. 35.16 MRI of the right ankle Tibia Fibula Talocrural joint Talus Deltoid lig. (posterior tibiotalar part) Talofibular joint Subtalar joint Posterior talofibular lig. Calcaneofibular joint Fibularis longus tendon Medial plantar a., v., and n. Calcaneus Abductor hallucis Flexor digitorum brevis Plantar aponeurosis Fig. 35.17 MRI of the right foot Coronal section, anterior (distal) view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) 35 Sectional & Radiographic Anatomy Coronal section, anterior view. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Dorsal Intermediate cuneiform Lateral cuneiform Medial cuneiform Metatarsal II (base) Abductor hallucis Metatarsal III (base) Metatarsal IV (base) Metatarsal V (base) Flexor digitorum brevis Interosseous mm. Abductor digiti minimi Fig. 35.18 MRI of the right foot and ankle Talonavicular joint Talocalcaneal interosseous lig. Talus Tibia Talocrural joint Calcaneal (Achilles) tendon) Sagittal section. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Subtalar joint Navicular Medial cuneiform Calcaneous Plantar calcaneonavicular lig. Proximal, middle, and distal phalanx of second toe Plantar aponeurosis Metatarsal II, head Adductor hallucis Intermediate cuneiform Quadratus plantae 509 Head & Neck 36 Surface Anatomy Surface Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512 37 Neck Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arteries & Veins of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . Lymphatics of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Innervation of the Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Larynx: Cartilage & Structure . . . . . . . . . . . . . . . . . . . . . . . . . Larynx: Muscles & Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Larynx, Thyroid & Parathyroids . . . Topography of the Neck: Regions & Fascia . . . . . . . . . . . . . . Topography of the Anterior Cervical Region . . . . . . . . . . . . . Topography of the Anterior & Lateral Cervical Regions . . . . Topography of the Lateral Cervical Region . . . . . . . . . . . . . . Topography of the Posterior Cervical Region . . . . . . . . . . . . 514 516 518 520 522 524 526 528 530 532 534 536 538 540 38 Bones of the Head Anterior & Lateral Skull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Posterior Skull & Calvaria . . . . . . . . . . . . . . . . . . . . . . . . . . . . Base of the Skull . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovascular Pathways Exiting or Entering the Cranial Cavity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ethmoid & Sphenoid Bones . . . . . . . . . . . . . . . . . . . . . . . . . . 542 544 546 548 550 39 Muscles of the Skull & Face Muscles of Facial Expression & of Mastication . . . . . . . . . . . . Muscle Origins & Insertions on the Skull . . . . . . . . . . . . . . . . Muscle Facts (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Muscle Facts (II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 554 556 558 40 Cranial Nerves Cranial Nerves: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN I & II: Olfactory & Optic Nerves . . . . . . . . . . . . . . . . . . . . CN III, IV & VI: Oculomotor, Trochlear & Abducent Nerves . . . CN V: Trigeminal Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN VII: Facial Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN VIII: Vestibulocochlear Nerve . . . . . . . . . . . . . . . . . . . . . . CN IX: Glossopharyngeal Nerve . . . . . . . . . . . . . . . . . . . . . . . CN X: Vagus Nerve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CN XI & XII: Accessory & Hypoglossal Nerves . . . . . . . . . . . . Autonomic Innervation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560 562 564 566 568 570 572 574 576 578 41 Neurovasculature of the Skull & Face Innervation of the Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arteries of the Head & Neck . . . . . . . . . . . . . . . . . . . . . . . . . . External Carotid Artery: Anterior, Medial & Posterior Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External Carotid Artery: Terminal Branches . . . . . . . . . . . . . . 580 582 584 586 Veins of the Head & Neck . . . . . . . . . . . . . . . . . . . . . . . . . . . . Meninges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dural Sinuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Superficial Face . . . . . . . . . . . . . . . . . . . . Topography of the Parotid Region & Temporal Fossa . . . . . . Topography of the Infratemporal Fossa . . . . . . . . . . . . . . . . . Neurovasculature of the Infratemporal Fossa . . . . . . . . . . . . 588 590 592 594 596 598 600 42 Orbit & Eye Bones of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602 Muscles of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .604 Neurovasculature of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . 606 Topography of the Orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608 Orbit & Eyelid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610 Eyeball . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612 Cornea, Iris & Lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614 43 Nasal Cavity & Nose Bones of the Nasal Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paranasal Air Sinuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Nasal Cavity . . . . . . . . . . . . . . . . . . Pterygopalatine Fossa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616 618 620 622 44 Temporal Bone & Ear Temporal Bone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . External Ear & Auditory Canal . . . . . . . . . . . . . . . . . . . . . . . . . Middle Ear: Tympanic Cavity . . . . . . . . . . . . . . . . . . . . . . . . . Middle Ear: Ossicular Chain & Tympanic Membrane . . . . . . . Arteries of the Middle Ear . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inner Ear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624 626 628 630 632 634 45 Oral Cavity & Pharynx Bones of the Oral Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Temporomandibular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oral Cavity Muscle Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Innervation of the Oral Cavity . . . . . . . . . . . . . . . . . . . . . . . . Tongue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Topography of the Oral Cavity & Salivary Glands . . . . . . . . . Tonsils & Pharynx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pharyngeal Muscles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neurovasculature of the Pharynx . . . . . . . . . . . . . . . . . . . . . . 636 638 640 642 644 646 648 650 652 654 46 Sectional & Radiographic Anatomy Sectional Anatomy of the Head & Neck (I). . . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (II) . . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (III). . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (IV). . . . . . . . . . . . . . Sectional Anatomy of the Head & Neck (V) . . . . . . . . . . . . . . Radiographic Anatomy of the Head & Neck (I). . . . . . . . . . . . Radiographic Anatomy of the Head & Neck (II). . . . . . . . . . . Radiographic Anatomy of the Head & Neck (III). . . . . . . . . . . 656 658 660 662 664 666 668 670 36 Surface Anatomy Head & Neck Surface Anatomy Fig. 36.1 Regions of the head and neck Parietal region Frontal region Orbital region Infraorbital region Temporal region Nasal region Zygomatic region Oral region Infratemporal region Parietal region Mental region Submandibular triangle Parotid-masseteric region Submental triangle Retromandibular region Anterior cervical region Carotid triangle Buccal region Posterior cervical region Temporal region Muscular (omotracheal) triangle Occipital region Sternocleidomastoid region Lateral cervical region Greater supraclavicular fossa Lesser supraclavicular fossa Jugular fossa A Right anterolateral view. Fig. 36.2 Surface anatomy of the head and neck Vertebra prominens Frontal bone Zygomatic bone Posterior cervical region Right posterolateral view. B Supraorbital margin Infraorbital margin Philtrum Helix Antihelix Tragus Antitragus Commissure of lips Mental protuberance Submandibular gland Mandibular angle Mandible, inferior border Thyroid cartilage Trapezius Clavicle Omohyoid, inferior belly Suprasternal notch Clavicular Sternal head head A Right anterolateral view. Jugular notch Sternocleidomastoid Parietal bone Occipital bone External occipital protuberance Nuchal lig. Mastoid process Mandibular angle Trapezius Sternocleidomastoid B Right posterolateral view. 512 Spinous process of C7 36 Surface Anatomy Fig. 36.3 Palpable bony prominences of the head and neck Frontal bone Frontal notch Supraorbital notch Nasal bone Zygomatic arch Infraorbital foramen Maxilla Mandibular angle Mental protuberance Mental foramen Body of hyoid bone Superior thyroid notch Laryngeal prominence Larynx Cricoid cartilage Clavicle Manubrium sterni Sternoclavicular joint Parietal bone Sagittal suture A Anterior view. Lambdoid suture Occipital bone External occipital protuberance Temporal bone Mastoid process Transverse process of atlas (C1) Mandibular angle Spinous processes Scapula, superior angle Vertebra prominens (C7) B Posterior view. 513 37 Neck Head & Neck Muscle Facts (I) The bones, joints, and ligaments of the neck and the six topographic classes of neck muscles are covered here in this unit with the neck, or in Unit 1 with the back (see Table 37.1). However, some muscles in the same topographic class belong in different functional classes; for example, the platysma belongs to the muscles of facial expression; the Table 37.1 trapezius, to the muscles of the shoulder girdle; and the nuchal muscles, to the intrinsic back muscles. Note that the suboccipital muscles (short nuchal and craniovertebral joint muscles) are covered with the lateral (deep) muscles of the neck. Bones, joints, ligaments, and muscles of the neck Bones, joints, and ligaments Bones of the cervical spine See pp. 8–9 Joints & ligaments of the craniovertebral junction See pp. 18–19 Joints & ligaments of the cervical spine See pp. 16– 17, 20-21 Hyoid bone & larynx Fig. 45.3, Fig. 37.18 Muscles I Superficial neck muscles III Platysma, ①, ② sternocleidomastoid, ③, ④, ⑤ trapezius II Fig. 37.3 Digastric, geniohyoid, mylohyoid, stylohyoid Nuchal muscles (intrinsic back muscles) ⑥ Semispinalis capitis ⑦ Semispinalis cervicis ⑧ Splenius capitis ⑨ Splenius cervicis ⑩ Longissimus capitis ⑪ Longissimus cervicis IV See p. 34 VI ⑫ Iliocostalis cervicis Fig. 37.1 Superficial neck muscles schematic Fig. 37.6C Fig. 37.4B Prevertebral muscles Longus capitis, longus coli, rectus capitis anterior and lateralis See p. 32 Fig. 37.4A Infrahyoid muscles Sternohyoid, sternothyroid, thyrohyoid, omohyoid V Suboccipital muscles (short nuchal and craniovertebral joint muscles) Suprahyoid muscles See p. 31 Fig. 37.6A Lateral (deep) neck muscles Anterior, middle, and posterior scalenes Fig. 37.6B Fig. 37.2 Nuchal muscles schematic See Table 37.2 for details. K H S J L A A Sternocleidomastoid. A Semispinalis. D B Splenius. Ö F Ä Y G B Trapezius. 514 C Longissimus. DIliocostalis. Fig. 37.3 Superficial neck muscles 37 Neck Depressor anguli oris Sternocleidomastoid Sternocleidomastoid Platysma Trapezius Trapezius A Anterior view. Clavicular head Sternal head B Left lateral view. Sternocleidomastoid Deep layer of nuchal fascia Trapezius Descending part Rhomboid minor Levator scapulae Transverse part Clavicle Acromion Scapular spine Supraspinatus C Posterior view. Removed: Trapezius (right side). Table 37.2 Superficial neck muscles Muscle Origin Insertion Innervation Action Platysma Skin over lower neck and upper lateral thorax Mandible (inferior border), skin over lower face and angle of mouth Cervical branch of facial n. (CN VII) Depresses and wrinkles skin of lower face and mouth, tenses skin of neck, aids forced depression of mandible Motor: Accessory n. (CN XI) Unilateral: Tilts head to same side, rotates head to opposite side Bilateral: Extends head, aids in respiration when head is fixed ① Sternal head Sternocleidomastoid Trapezius Sternum (manubrium) ② Clavicular head Clavicle (medial one third) Temporal bone (mastoid process), occipital bone (superior nuchal line) ③ Descending part* Occipital bone, spinous processes of C1–C7 Clavicle (lateral one third) Proprioception: Cervical plexus (C2, C3, [C4]) Draws scapula obliquely upward, rotates glenoid cavity superiorly * The transverse ④ and ascending ⑤ parts are described on p. 320. 515 Head & Neck Muscle Facts (II) Suprahyoid muscles Table 37.3 The suprahyoid muscles are also considered accessory muscles of mastication. Muscle Origin Insertion 1a Anterior belly Mandible (digastric fossa) 1b Posterior belly Temporal bone (mastoid notch, medial to mastoid process) Digastric ② Stylohyoid Via an intermediate tendon with a fibrous loop Temporal bone (styloid process) ③ Mylohyoid ④ Geniohyoid Via a split tendon Hyoid bone (body) Mandible (mylohyoid line) Innervation Mandible (inferior mental spine) Mylohyoid n. (from CN V3) Facial n. (CN VII) Action Elevates hyoid bone (during swallowing), assists in opening mandible Via median tendon of insertion (mylohyoid raphe) Mylohyoid n. (from CN V3) Tightens and elevates oral floor, draws hyoid bone forward (during swallowing), assists in opening mandible and moving it side to side (during mastication) Directly Anterior ramus of C1 via hypoglossal n. (CN XII) Draws hyoid bone forward (during swallowing), assists in opening mandible Fig. 37.4 Suprahyoid and infrahyoid muscles S D K 1b G F 1a H A Suprahyoid muscles, left lateral view. Table 37.4 B Infrahyoid muscles, anterior view. Infrahyoid muscles Muscle Origin Insertion Innervation ⑤ Omohyoid Scapula (superior border) – inferior belly ⑥ Sternohyoid Manubrium and sternoclavicular joint (posterior surface) Hyoid bone (body) – superior belly Ansa cervicalis (C1–C3) of cervical plexus ⑦ Sternothyroid Manubrium (posterior surface) Thyroid cartilage (oblique line) Ansa cervicalis (C1–C3) of cervical plexus ⑧ Thyrohyoid Thyroid cartilage (oblique line) Hyoid bone (body) Anterior ramus of C1 via hypoglossal n. (CN XII) * The omohyoid also tenses the cervical fascia (via its intermediate tendon). 516 J Action Depresses (fixes) hyoid, draws larynx and hyoid down for phonation and terminal phases of swallowing* Depresses and fixes hyoid, raises the larynx during swallowing Fig. 37.5 Suprahyoid and infrahyoid muscles 37 Neck Stylohyoid Digastric, posterior belly Digastric, anterior belly Thyrohyoid Mylohyoid Sternohyoid Sternothyroid Omohyoid, superior and inferior bellies Intermediate tendon of omohyoid Coronoid process Geniohyoid Mylohyoid line A Left lateral view. Head of mandible Mylohyoid Mylohyoid raphe Hyoid bone Thyrohyoid Thyroid cartilage Sternothyroid Anterior belly Mandibular ramus Digastric Posterior belly Stylohyoid Mylohyoid Hyoid bone (body) B Mylohyoid and geniohyoid (oral floor), posterosuperior view. Sternohyoid Omohyoid, superior and inferior bellies C Anterior view. The sternohyoid has been cut (right). 517 Muscle Facts (III) Head & Neck Fig. 37.6 Deep muscles of the neck D A F S ⑥ ⑦ ⑤ A Prevertebral muscles, anterior view. K B Scalene muscles, anterior view. L Ö Ä C Suboccipital muscles, posterior view. Deep muscles of the neck Table 37.5 Muscle Origin Insertion Innervation Action C3–C6 (anterior tubercles of transverse processes) Occipital bone (basilar part) Anterior rami of C1–C3 Flexion of head at atlanto-occipital joints Vertical (intermediate) part C5–T3 (anterior surfaces of vertebral bodies) C2–C4 (anterior surfaces) Superior oblique part C3–C5 (anterior tubercles of transverse processes) Atlas (anterior tubercle) Anterior rami of C2–C6 Unilateral: Tilts and rotates cervical spine to opposite side Inferior oblique part T1–T3 (anterior surfaces of vertebral bodies) C5–C6 (anterior tubercles of transverse processes) C1 (lateral mass) Occipital bone (basilar part) Prevertebral muscles ① Longus capitis ② Longus colli ③ Rectus capitis anterior Bilateral: Forward flexion of cervical spine C1 (transverse process) Occipital bone (basilar part, lateral to occipital condyles) Anterior rami of C1 and C2 ⑤ Anterior scalene C3–C6 (anterior tubercles of transverse processes) 1st rib (scalene tubercle) Anterior rami of C4–C6 ⑥ Middle scalene C1–C2 (transverse processes), C3–C7 (posterior tubercles of transverse processes) 1st rib (posterior to groove for subclavian a.) Anterior rami of C3–C8 C5–C7 (posterior tubercles of transverse processes) 2nd rib (outer surface) Anterior rami of C6–C8 ④ Rectus capitis lateralis Unilateral: Lateral flexion of the head at the atlanto-occipital joint Bilateral: Flexion of the head at the atlantooccipital joint Scalene muscles ⑦ Posterior scalene With ribs mobile: Elevates upper ribs (during forced inspiration) With ribs fixed: Flexes cervical spine to same side (unilateral), flexes neck (bilateral) Suboccipital muscles (short nuchal and craniovertebral joint muscles) ⑧ Rectus capitis posterior minor ⑨ Rectus capitis posterior major C1 (posterior tubercle) C2 (spinous process) ⑩ Obliquus capitis inferior ⑪ Obliquus capitis superior 518 Occipital bone (inner third of inferior nuchal line) Occipital bone (middle third of inferior nuchal line) C1 (transverse process) C1 (transverse process) Occipital bone (above insertion of rectus capitis posterior major) Unilateral: Rotates head to same side Posterior ramus of C1 (suboccipital n.) Bilateral: Extends head Unilateral: Tilts head to same side, rotates it to opposite side Bilateral: Extends head Superior nuchal line Inferior nuchal line Fig. 37.7 Deep muscles of the neck Rectus capitis posterior minor 37 Neck Obliquus capitis superior Mastoid process Rectus capitis posterior major Posterior tubercle of atlas (C1) Transverse process of atlas (C1) Spinous process of axis (C2) Obliquus capitis inferior A Suboccipital muscles, posterior view. Rectus capitis anterior Rectus capitis lateralis Atlas (C1) Longus capitis Superior oblique part Vertical part Longus colli Inferior oblique part Middle scalene Anterior scalene Middle scalene Posterior scalene Posterior scalene Interscalene space Anterior scalene (cut) Groove for subclavian a. 2nd rib Prevertebral and scalene B muscles, anterior view. Removed: Longus capitis and anterior scalene (left). Scalene tubercle 1st rib 519 Head & Neck Arteries & Veins of the Neck Fig. 37.8 Arteries of the neck Left lateral view. The structures of the neck are primarily supplied by the external carotid artery (anterior branches) and the subclavian artery (vertebral artery, thyrocervical trunk, and costocervical trunk). Vertebral a. Ascending pharyngeal a. External carotid a. Internal carotid a. Infrahyoid br. Superior thyroid a. Vertebral a. Superior laryngeal a. Deep cervical a. Inferior thyroid a. Cricothyroid br. Ascending cervical a. Transverse cervical a. Common carotid a. Suprascapular a. Internal thoracic a. Thyrocervical trunk Highest intercostal a. Left subclavian a. 520 Costocervical trunk Axillary a. 37 Neck Fig. 37.9 Veins of the neck Left lateral view. The principal veins of the neck are the internal, external, and anterior jugular veins. Superior and inferior ophthalmic vv. Superior sagittal sinus Angular v. Cavernous sinus Transverse sinus Superficial temporal v. Pterygoid plexus Occipital v. Posterior auricular v. Maxillary v. Lingual v. Retromandibular v. Facial v. Deep cervical v. Superior thyroid v. External jugular v. Anterior jugular v. Vertebral v. Internal jugular v. Jugular venous arch Left brachiocephalic v. Subclavian v. Clinical box 37.1 Impeded blood flow and veins of the neck When clinical factors (e.g., chronic lung disease, mediastinal tumors, or infections) impede the flow of blood to the right heart, blood dams up in the superior vena cava and, consequently, the jugular veins (A). This causes conspicuous swelling in the jugular (and sometimes more minor) veins (B). External jugular v. Internal jugular v. External jugular v. External jugular v. Jugular Internal venous arch External jugular v. Sternocleidomastoid Sternocleidomastoid jugular v. Jugular Left brachiovenous arch Subclavian v. Subclavian v. A Superior vena cava Superior vena cava cephalic v. Left brachiocephalic v. Trapezius B Trapezius 521 Head & Neck Lymphatics of the Neck Fig. 37.10 Lymphatic drainage regions Right lateral view. Parotidauricular Occipital Buccal Facial Nuchal Jugulofacial venous junction Submentalsubmandibular Parallel to internal jugular vein Laryngotracheothyroidal Along the accessory nerve Jugulosubclavian venous junction Axillary Fig. 37.11 Lymphatic drainage of the tongue and oral floor Lymph flows into the submental and submandibular lymph nodes of the tongue and oral floor, which ultimately drain into the jugular lymph nodes along the internal jugular vein. Because the lymph nodes receive drainage from both the ipsilateral and contralateral sides (B), tumor cells may become widely disseminated in this region (e.g., metastatic squamous cell carcinoma, especially on the lateral border of the tongue, frequently metastasizes to the opposite side). Superior deep cervical l.n. Lingual v. Submental l.n. Superior deep cervical l.n. Jugulofacial venous junction Submandibular l.n. Inferior deep cervical l.n. Internal jugular v. Inferior deep cervical l.n. A Lateral view. 522 B Coronal section showing that lymphatic drainage from one side of the tongue can drain to either side of the neck. Fig. 37.12 Superficial cervical lymph nodes Right lateral view. Retroauricular l.n. Superficial parotid l.n. 37 Neck Occipital l.n. Mastoid l.n. Facial v. Deep parotid l.n. Superficial cervical lymph nodes Table 37.6 Lymph nodes (l.n.) Anterior superficial cervical l.n. Drainage region Retroauricular l.n. Occipital l.n. External jugular v. Occiput Mastoid l.n. Lateral superficial cervical l.n. Superficial parotid l.n. Deep parotid l.n. Anterior superficial cervical l.n. Lateral superficial cervical l.n. Parotid-auricular region Sternocleidomastoid region Fig. 37.13 Deep cervical lymph nodes Right lateral view. Submandibular l.n. II I Submental l.n. V III Level VI Internal jugular v. IV Table 37.7 I Deep cervical lymph nodes Lymph nodes (l.n.) Submental l.n. Face Submandibular l.n. Upper lateral group II III Drainage region Lateral jugular l.n. group Middle lateral group Nuchal region, laryngotracheo-thyroidal region Lower lateral group IV V L.n. in posterior cervical triangle Nuchal region VI Anterior cervical l.n. Laryngo-tracheo-thyroidal region 523 Head & Neck Innervation of the Neck Branches of the spinal nerves in the neck Table 37.8 Posterior (dorsal) ramus Nerve Sensory function C1 Suboccipital n. No C1 dermatome Motor function C2 Greater occipital n. Innervate C2 dermatome C3 3rd occipital n. Innervate C3 dermatome Hypoglossal n. (CN XII) Innervate intrinsic nuchal muscles C1 Lesser occipital n. C2 Anterior (ventral) ramus C1 C2 C2– C3 C3– C4 Great auricular n. Sensory branches Sensory function — — Motor branches Motor function Ansa cervicalis Lesser occipital n. Great auricular n. Transverse cervical n. Supraclavicular nn. Form sensory part of cervical plexus, innervate anterior and lateral neck Form ansa cervicalis (motor part of cervical plexus) C3 Superior root Innervate infrahyoid muscles (except thyrohyoid) C4 Inferior root C5 Transverse cervical n. Supraclavicular nn. To brachial plexus Phrenic n. Contribute to phrenic n.* Innervate diaphragm and pericardium* Branching of the cervical plexus. * The anterior roots of C3–C5 combine to form the phrenic nerve (see p. 66). Fig. 37.14 Sensory innervation of the ­nuchal region Posterior view. Ophthalmic n. (CN V1) C2 Lesser occipital n. C3 Suboccipital n. (in suboccipital triangle) C4 Great auricular n. A Dermatomes. Greater occipital n. Ophthalmic n. (CN V1) 3rd occipital n. Greater occipital n. Supraclavicular nn. Lesser occipital n. Posterior rami of spinal nn. B Cutaneous nerve territories. 524 Great auricular n. Supraclavicular nn. C5 spinal n., posterior ramus C Spinal nerve branches. Fig. 37.15 Sensory innervation of the anterolateral neck Left lateral view. Greater occipital n.+ Lesser occipital n. Lesser occipital n.* Maxillary n. (CN V2) Great auricular n. Great auricular n.* Mandibular n. (CN V3) Transverse cervical n. Posterior rami of spinal nn.+ Transverse cervical n.* 37 Neck Ophthalmic n. (CN V1) Supraclavicular nn. Supraclavicular nn.* A Cutaneous nerve territories. Trigeminal nerve, CN V3 (orange), posterior rami (+), anterior rami (*). B Sensory branches of the cervical plexus. Fig. 37.16 Motor innervation of the anterolateral neck Left lateral view. Hypoglossal n. (CN XII) C1, anterior ramus C1 C2 Superior root of ansa cervicalis Geniohyoid* Thyrohyoid* Infrahyoid muscles Omohyoid C4 Inferior root of ansa cervicalis Phrenic n. Ansa cervicalis Sternohyoid Sternothyroid Anterior scalene Middle scalene * Innervated by the anterior ramus of C1 (distributed by the hypoglossal n.). 525 Head & Neck Larynx: Cartilage & Structure Fig. 37.17 Laryngeal cartilages Fig. 37.18 Epiglottic cartilage Left lateral view. The larynx consists of five laryngeal cartilages: epiglottic, thyroid, cricoid, and the paired arytenoid and corniculate cartilages. They are connected to each other, the trachea, and the hyoid bone by elastic ligaments. Lesser horn Epiglottis The elastic epiglottic cartilage comprises the internal skeleton of the epiglottis, providing resilience to return it to its initial position after swallowing. Epiglottic cartilage Greater horn Hyoid bone (body) Stalk of epiglottis A Lingual (anterior) view. Thyroid cartilage B Left lateral view. C Laryngeal (posterior) view. Fig. 37.19 Thyroid cartilage Left oblique view. Right lamina Cricoid cartilage Superior horn Superior thyroid notch Trachea Superior tubercle Laryngeal prominence Left lamina Oblique line Inferior thyroid notch Inferior tubercle Fig. 37.20 Cricoid cartilage Articular facet for arytenoid cartilage Articular facet for thyroid cartilage A Anterior view. Arch Articular facet for arytenoid cartilage Arch Fig. 37.21 Arytenoid and corniculate cartilages C Posterior view. Apex Corniculate cartilage Colliculus Right cartilages. Posterior surface Anterolateral surface Arytenoid cartilage Vocal process Vocal process Muscular process A Right lateral view. 526 Lamina Articular facet for thyroid cartilage B Left lateral view. Corniculate cartilage Inferior horn Articular facet Muscular process Medial surface B Medial view. C Posterior view. 37 Neck Fig. 37.22 Structure of the larynx The larynx is suspended from the hyoid bone, primarily by the thyrohyoid membrane. The hyoid bone provides the sites for attachment of the suprahyoid and infrahyoid muscles. Epiglottis Thyrohyoid membrane Hyoid bone Median thyrohyoid lig. Laryngeal prominence Thyrohyoid lig. Cricotracheal lig. Vestibular lig. Corniculate cartilage Superior horn Thyroid cartilage Cricothyroid lig. Vocal lig. Foramen for superior laryngeal a. and v. and internal laryngeal n. Arytenoid cartilage Vocal process Thyroid cartilage Cricoarytenoid joint Cricothyroid joint Cricoid cartilage Median cricothyroid lig. Cricoid cartilage Cricotracheal lig. A Left anterior oblique view. B Sagittal section, viewed from the left medial aspect. The arytenoid cartilage alters the position of the vocal folds during phonation. Lesser horn Greater horn Thyrohyoid membrane Superior horn Thyroepiglottic lig. Inferior horn Epiglottic cartilage Foramen for superior laryngeal a. and v. and internal laryngeal n. Corniculate cartilage Cricoarytenoid lig. Median cricothyroid lig. Thyroid cartilage Vocal lig. Conus elasticus Arch of cricoid cartilage Vocal process Muscular process Colliculus Cricothyroid joint C Posterior view. Arrows indicate the directions of movement in the various joints. Corniculate cartilage Lamina of cricoid cartilage Cricoarytenoid lig. DSuperior view. 527 Head & Neck Larynx: Muscles & Levels Fig. 37.23 Laryngeal muscles The laryngeal muscles move the laryngeal cartilages relative to one another, affecting the tension and/or position of the vocal folds. Muscles that move the larynx as a whole (infra- and suprahyoid muscles) are described on p. 516. Thyroarytenoid muscle, thyroepiglottic part Aryepiglottic fold Cuneiform tubercle Thyroarytenoid Cricothyroid Corniculate tubercle Lateral cricoarytenoid Straight part Posterior cricoarytenoid Oblique part A Intrinsic laryngeal muscles, left lateral oblique view. B Intrinsic laryngeal muscles, left lateral view. Removed: Thyroid cartilage (left half). Revealed: Epiglottis and thyroarytenoid muscle. Epiglottis Arytenoid cartilage, vocal process Aryepiglottic fold Cuneiform tubercle Oblique arytenoid Vocalis Arytenoid cartilage, muscular process Conus elasticus Lateral cricoarytenoid Posterior cricoarytenoid Middle cricoarytenoid lig. Oblique arytenoid Posterior cricoarytenoid Articular facet for thyroid cartilage C Left lateral view with the epiglottis removed. DPosterior view. Table 37.9 A S B Open rima glottidis. D Actions of the laryngeal muscles G A Laryngeal muscles, superior view. H C Closed rima glottidis. Effect on rima glottidis Muscle Action ① Cricothyroid m.* Tightens the vocal folds None Adducts the vocal folds Closes ⑤ Posterior cricoarytenoid m. Abducts the vocal folds Opens ⑥ Lateral cricoarytenoid m. Adducts the vocal folds Closes ② Vocalis m. ③ Thyroarytenoid m. ④ Transverse arytenoid m. F 528 Thyroarytenoid Transverse arytenoid * The cricothyroid is innervated by the external laryngeal n. All other intrinsic laryngeal mm. are innervated by the recurrent laryngeal n. Levels of the larynx Table 37.10 Level Space Extent I Supraglottic space (laryngeal vestibule) Laryngeal inlet (aditus laryngis) to vestibular folds II Transglottic space (intermediate laryngeal cavity) Vestibular folds across laryngeal ventricle (lateral evagination of mucosa) to vocal folds III Subglottic space (infraglottic cavity) Vocal folds to inferior border of cricoid cartilage II III Posterior view. 37 Neck I Fig. 37.24 Cavity of the larynx Lingual tonsil Epiglottis Vestibular fold Ventricle Epiglottis Hyoid bone Piriform recess Hyoepiglottic lig. Vocal fold Thyrohyoid lig. Cricoid cartilage Vestibular fold Thyroid cartilage Aryepiglottic fold Cuneiform tubercle Corniculate tubercle Vocal fold Cricoid cartilage Median cricothyroid lig. A Posterior view with the larynx splayed open. Cricoid cartilage Esophagus Tracheal cartilage Membranous wall of trachea B Midsagittal section viewed from the left side. Fig. 37.25 Vestibular and vocal folds Coronal section, superior view. Quadrangular membrane Epiglottic cartilage Thyroid cartilage Glands Rima vestibuli Laryngeal saccule Laryngeal ventricle Vestibular lig. Rima glottidis Vocal lig. Conus elasticus Vocalis Thyroarytenoid 529 Head & Neck Neurovasculature of the Larynx, Thyroid & Parathyroids Fig. 37.26 Thyroid and parathyroid glands Thyroid cartilage Pyramidal lobe, thyroid gland Median cricothyroid lig. Cricothyroid Right lobe, thyroid gland Superior thyroid a. Left lobe, thyroid gland Isthmus of thyroid gland Parathyroid glands, superior pair Trachea Parathyroid glands, inferior pair A Thyroid gland, anterior view. Inferior thyroid a. B Thyroid and parathyroid glands, posterior view. Parathyroid glands Trachea Pretracheal visceral layer Pretracheal muscular layer Platysma Thyroid gland Investing (superficial) layer Sternocleidomastoid Internal jugular v. Carotid sheath Common carotid a. Vagus n. Esophagus Investing (superficial) layer Prevertebral layer Buccopharyngeal fascia (continuous with pretracheal layer) Retropharyngeal space Muscular pretracheal layer Visceral pretracheal layer Carotid sheath Prevertebral layer 530 C T ransverse section of neck at level of C6, superior view. Topographical relations of the thyroid and parathyroid glands. See p. 533 for coverage of the layers of the deep cervical fascia, which are shown here. Fig. 37.27 Arteries and nerves of the larynx Anterior view. Removed: Thyroid gland (right half). Left vagus n. (CN X) Superior thyroid a. Superior laryngeal n. Superior laryngeal a. Internal laryngeal n. Common carotid a. External laryngeal n. Fig. 37.28 Veins of the larynx 37 Neck Right vagus n. (CN X) Left lateral view. Note: The inferior thyroid vein generally drains into the left brachiocephalic vein. Cricothyroid br. Inferior laryngeal a. Recurrent laryngeal nn. Inferior thyroid a. Thyrocervical trunk Left subclavian a. Right recurrent laryngeal n. Left recurrent laryngeal n. Aortic arch Facial v. Superior thyroid v. Superior laryngeal v. Middle thyroid vv. Inferior laryngeal v. Thyroid venous plexus Internal jugular v. Inferior thyroid v. Left brachiocephalic v. Subclavian v. Fig. 37.29 Neurovasculature of the larynx Left lateral view. Epiglottis Superior laryngeal n. Internal laryngeal n. Hyoid bone Superior laryngeal a. and v. Thyrohyoid membrane Thyrohyoid Inferior pharyngeal constrictor External laryngeal n. Median cricothyroid lig. Cricothyroid Middle thyroid v. Inferior thyroid a. Thyroid gland Esophagus A Superficial layer. Left recurrent laryngeal n. Hyoid bone Median thyrohyoid lig. Thyroarytenoid Lateral cricoarytenoid Median cricothyroid lig. Cricothyroid Tracheal brs. Internal laryngeal n. Superior laryngeal a. and v. Galen’s anastomosis Posterior cricoarytenoid Esophagus Middle thyroid v. Inferior thyroid a. Left recurrent laryngeal n. B Deep layer. Removed: Cricothyroid muscle and left lamina of thyroid cartilage. Retracted: Pharyngeal mucosa. 531 Head & Neck Topography of the Neck: Regions & Fascia Table 37.11 Region ① Anterior cervical region (triangle) ② ① ③ Regions of the neck Divisions Contents Submandibular (digastric) triangle Submandibular gland and l.n., hypoglossal n. (CN XII), facial a. and v. Submental triangle Submental l.n. Muscular triangle Sternothyroid and sternohyoid mm., thyroid and parathyroid glands Carotid triangle Carotid bifurcation, carotid body, hypoglossal (CN XII) and vagus (CN X) nn. ② Sternocleidomastoid region* F ③ Lateral cervical region (posterior triangle) A Right anterior oblique view. B Left posterior oblique view. Sternocleidomastoid, common carotid a., internal jugular v., vagus n. (CN X), jugular l.n. Omoclavicular (subclavian) triangle Subclavian a., subscapular a., supraclavicular l.n. Occipital triangle Accessory n. (CN XI), trunks of brachial plexus, transverse cervical a., cervical plexus (posterior branches) Nuchal mm., vertebral a., cervical plexus ④ Posterior cervical region * The sternocleidomastoid region also contains the lesser supraclavicular fossa. Omohyoid, superior belly Fig. 37.30 Cervical regions Submandibular triangle Submandibular (digastric) triangle Digastric, anterior and posterior bellies Digastric, posterior belly Digastric, anterior belly Sternocleidomastoid Submental triangle Occipital triangle Carotid triangle Submental triangle Trapezius Omohyoid, inferior belly Sternohyoid Hyoid bone Omoclavicular (subclavian) triangle Sternocleidomastoid Carotid triangle Omohyoid, superior belly Occipital triangle Lesser supraclavicular fossa Trapezius Omoclavicular (subclavian) triangle A Anterior view. 532 Lesser supraclavicular fossa Muscular triangle Omohyoid, inferior belly B Left lateral view. Clavicle Table 37.12 Deep cervical fascia The deep cervical fascia is divided into four layers that enclose the structures of the neck. ① Investing (superficial) layer Pretracheal layer Type of fascia Description Muscular Envelopes entire neck; splits to enclose sternocleidomastoid and trapezius muscles ② Muscular Encloses infrahyoid muscles ③ Visceral Surrounds thyroid gland, larynx, trachea, pharynx, and esophagus ④ Prevertebral layer Muscular Surrounds cervical vertebral column and associated muscles ⑤ Carotid sheath Neurovascular Encloses common carotid artery, internal jugular vein, and vagus nerve 37 Neck Layer ① Superficial ③ Visceral layer of deep pretracheal fascia cervical fascia ② Muscular pretracheal fascia Retropharyngeal space ① Nuchal lig. Carotid sheath ⑤ Prevertebral fascia ④ Prevertebral layer (deep nuchal fascia) Buccopharyngeal fascia ① Spinal cord ② ④ ③ Superficial layer of deep cervical (superficial nuchal) fascia A Transverse section at level of C5 vertebra. B Midsagittal section, left lateral view. Fig. 37.31 Deep cervical fascial layers Anterior view. Mandible Parotid gland ① Investing (superficial) layer Sternohyoid ③ Pretracheal visceral layer ② Pretracheal muscular layer Sternocleidomastoid Carotid sheath ⑤ Omohyoid Prevertebral layer ④ Trapezius Clavicle 533 Head & Neck Topography of the Anterior Cervical Region Fig. 37.32 Anterior cervical triangle Anterior view. Mandible Facial n. (CN VII), cervical br. Parotid gland Investing layer of deep cervical fascia Platysma External jugular v. Anterior jugular v. Great auricular n. Pretracheal layer of deep cervical fascia Transverse cervical n. A Superficial layer. Removed: Subcutaneous platysma (right side) and investing layer of deep cervical fascia (center). Supraclavicular nn. Superior laryngeal a. Internal jugular v. External laryngeal n. Right common carotid a. Superior thyroid a. External jugular v. Sternocleidomastoid, sternal head Internal laryngeal n. Jugular venous arch Thyroid cartilage Hypoglossal n. (CN XII) Thyrohyoid br. (C1 via CN XII) Median thyrohyoid lig. Thyrohyoid Omohyoid, superior belly (cut) Sternocleidomastoid Cricothyroid Sternothyroid B Deep layer. Removed: Pretracheal lamina (middle layer of cervical fascia). Cuts: Sternohyoid, sternothyroid, and thyrohyoid (right side); sternohyoid (left side). 534 Sternohyoid (cut) Superior laryngeal a. Internal laryngeal n. Superior thyroid a. 37 Neck Internal jugular v. Thyroid cartilage Vagus n. (CN X) Accessory n. (CN XI) Trapezius Phrenic n. External laryngeal n. Brachial plexus Cricothyroid Ascending cervical a. Internal jugular v. Inferior thyroid a. Suprascapular n. Thyrocervical trunk Transverse cervical a. Suprascapular a. Vagus n. (CN X) Subclavian v. Subclavian a. Thyrocervical trunk C Deep anterior cervical region. Inferior thyroid v. Median thyrohyoid lig. Inferior laryngeal n. Thyroid cartilage Common carotid a. Left common carotid a. Internal jugular v. Vagus n. (CN X) External laryngeal n. Accessory n. (CN XI) Trapezius Middle cervical ganglion Phrenic n. Cricothyroid Anterior scalene Sympathetic trunk Brachial plexus Inferior thyroid a. Ascending cervical a. C8, anterior root Transverse cervical a. Vertebral a. Suprascapular a. T1, anterior root External jugular v. Left recurrent laryngeal n. Subclavian a. and v. Stellate ganglion DRoot of the neck. Left common carotid a. Thoracic duct Internal thoracic a. Thyrocervical trunk 535 Head & Neck Topography of the Anterior & Lateral Cervical Regions Fig. 37.33 Deep anterior cervical region The deep midline viscera of the anterior cervical region are the larynx and thyroid gland. The two lateral neurovascular pathways primarily supply these organs. Mandible Parotid gland Parotid gland Mylohyoid Digastric, anterior belly Hyoid Sternocleidomastoid Thyrohyid membrane (median thyrohyoid lig.) Thyroid cartilage Internal jugular v. Cricothyroid Pyramidal lobe Phrenic n. Thyroid gland Right common carotid a. Thyrocervical trunk Subclavian a. Brachiocephalic trunk 536 Sternohyoid Thyrohyoid Superior thyroid a. Superior thyroid v. Middle scalene Trapezius Accessory n. Anterior scalene Brachial plexus Vagus n. Phrenic n. Transverse cervical a. Middle thyroid v. Inferior thyroid vv. Left recurrent laryngeal n. Clavicle Left common carotid a. Fig. 37.34 Carotid triangle Digastric, posterior belly Right lateral view. Internal jugular and facial veins removed. Internal carotid a. External carotid a. Facial a. Hypoglossal n. (CN XII) Facial n. (CN VII) marginal mandibular br. Superior cervical ganglion 37 Neck Lingual a. Internal jugular v. (cut) Submandibular gland Occipital a. Superior laryngeal n. Vagus n. Superior root of ansa cervicalis (descendens hypoglossus) Hyoid bone Thyrohyoid br. (C1 via CN XII) Carotid body Superior thyroid a. Common carotid a. Thyrohyoid Sternocleidomastoid Investing layer of deep cerical fascia Sternothyroid Omohyoid, superior belly Ansa cervicalis Fig. 37.35 Deep lateral cervical region Right lateral view with sternocleidomastoid windowed. Internal carotid a. External carotid a. Facial a. and v. Hypoglossal n. (CN XII) Superior cervical ganglion Sympathetic trunk Accessory n. (CN XI) Middle scalene Anterior scalene Internal jugular v. Superficial cervical a. Carotid body Carotid bifurcation Superior thyroid a. Thyroid gland Common carotid a. Ansa cervicalis Sternohyoid Phrenic n. Inferior thyroid a. Brachial plexus Omohyoid, inferior belly Vagus n. (CN X) Sternothyroid Sternocleidomastoid 537 Head & Neck Topography of the Lateral Cervical Region Fig. 37.36 Lateral cervical region Parotid gland Right lateral view. The contents of the deep lateral cervical region are found in Fig. 37.34. Facial n. (CN VII), cervical br. Masseter Lesser occipital n. Great auricular n. Erb’s point External jugular v. Lateral supraclavicular nn. Sternocleidomastoid, posterior border Trapezius, anterior border Transverse cervical and CN VII anastomosis Superficial (investing) layer of deep cervical fascia Transverse cervical n. Clavicle A Subcutaneous layer. Intermediate supraclavicular nn. Medial supraclavicular nn. Lesser occipital n. Great auricular n. Accessory n. (CN XI) External jugular v. Erb’s point Superficial (investing) layer of deep cervical fascia Superficial cervical l.n. Superficial cervical a. Sternocleidomastoid Trapezius Transverse cervical n. Supraclavicular nn. Prevertebral layer of deep cervical fascia Superficial cervical v. 538 Pretracheal layer of deep cervical fascia B Subfascial layer. Removed: Superficial (investing) layer of deep cervical fascia. Parotid gland 37 Neck Lesser occipital n. Great auricular n. Accessory n. (CN XI) Lateral supraclavicular n. Intermediate supraclavicular n. External jugular v. Sternocleidomastoid Trapezius Superficial cervical a. and v. Prevertebral layer of deep cervical fascia Transverse cervical n. Right subclavian v. Omohyoid, inferior belly C Deep layer. Removed: Pretracheal layer of deep cervical fascia. Revealed: Omohyoid, omoclavicular (subclavian) triangle. Splenius capitis Accessory n. (CN XI) Levator scapulae Middle scalene Trapezius Posterior scalene Superficial cervical a. DDeepest layer. Removed: Prevertebral layer of deep cervical fascia. Revealed: Muscular floor of posterior triangle, brachial plexus, and phrenic nerve. Omohyoid, inferior belly Phrenic n. Sternocleidomastoid Brachial plexus Anterior scalene Suprascapular a. Right subclavian v. 539 Head & Neck Topography of the Posterior Cervical Region Fig. 37.37 Occipital and posterior cervical regions Posterior view. Subcutaneous layer (left), subfascial layer (right). The occiput is technically a region of the head, but it is included here due to the continuity of the vessels and nerves from the neck. Removed on right side: Investing layer of deep cervical fascia. Occipital a. and v. Greater occipital n. Occipital l.n . Semispinalis capitis 3rd occipital n. Lesser occipital n. Lesser occipital n. Sternocleidomastoid Splenius capitis Great auricular n. Accessory n. (CN XI) Posterior cutaneous br. (cervical nn., posterior rami) 540 Trapezius 37 Neck Fig. 37.38 Suboccipital triangle Right side, posterior view, windowed. The suboccipital triangle is bounded by the suboccipital muscles (rectus capitis posterior major and obliquus capitis superior and inferior) and contains the vertebral artery. The left and right vertebral arteries pass through the atlantooccipital membrane and combine to form the basilar artery. Occipital a. Splenius capitis Sternocleidomastoid Semispinalis capitis Obliquus capitis superior Rectus capitis posterior minor Greater occipital n. Suboccipital n. Vertebral a. Rectus capitis posterior major Obliquus capitis inferior Spinous process of axis (C2) Occipital a. Great auricular n. Transverse process of atlas (C1) Cervical posterior intertransversarius 3rd occipital n. Longissimus capitis Spinous process of C3 Semispinalis capitis Splenius capitis 541 38 Bones of the Head Head & Neck Anterior & Lateral Skull Fig. 38.1 Lateral skull Left lateral view. Frontal bone Coronal suture Pterion Squamous suture Parietal bone Sphenoparietal suture Sphenofrontal suture Sphenosquamous suture Supraorbital foramen Glabella Sphenoid bone, greater wing Ethmoid bone Lacrimal bone Zygomatic bone, temporal process Nasal bone Zygomatic bone, frontal process Temporal bone, zygomatic process Infraorbital foramen Anterior nasal spine Maxilla, zygomatic process Lambdoid suture Mastoid Asterion foramen Tympanomastoid fissure External acoustic meatus Postglenoid tubercle Styloid process Articular tubercle (articular eminence) Mandible, body Oblique line Mental protuberance Mastoid process Zygomatic Mandible, arch ramus Zygomatic bone Mental foramen Table 38.1 Bones of the skull The skull is subdivided into the neurocranium (gray) and viscerocranium (orange). The neurocranium protects the brain, while the viscerocranium houses and protects the facial regions. Neurocranium Viscerocranium • Ethmoid bone (cribriform plate)* • Frontal bone • Occipital bone • Parietal bone • Sphenoid bone • Temporal bone (petrous and squamous parts) • Mandible • Ethmoid bone • Maxilla • Hyoid bone • Nasal bone • Inferior nasal concha • Palatine bone • Lacrimal bone • Sphenoid bone (pterygoid process) • Temporal bone • Vomer *Most of the ethmoid bone is in the viscerocranium; most of the sphenoid bone is in the neurocranium. The temporal bone is divided between the two. 542 Fig. 38.2 Anterior skull Anterior view. Nasion Superciliary arch Frontal bone Maxilla, frontal process Parietal bone Frontal incisure (notch) Supraorbital foramen Supraorbital margin Nasal bone Sphenoid bone, greater wing Sphenoid bone, lesser wing Temporal bone 38 Bones of the Head Glabella Orbit Ethmoid bone, perpendicular plate Sphenoid bone, greater wing Infraorbital margin Ethmoid bone, middle nasal concha Zygomatic bone, frontal process Piriform (anterior nasal) aperture Maxilla, zygomatic process Vomer Infraorbital foramen Inferior nasal concha Anterior nasal spine Mandible, ramus Intermaxillary suture Oblique line Maxilla, alveolar process Mandible, body Mental foramen Mental protuberance Mental tubercles Clinical box 38.1 Fractures of the face The framelike construction of the facial skeleton leads to characteristic patterns for fracture lines (classified as Le Fort I, II, and III fractures). A Le Fort I. B Le Fort II. C Le Fort III. 543 Head & Neck Posterior Skull & Calvaria Fig. 38.3 Posterior skull Posterior view. Parietal foramina Lambda Sagittal suture Parietal bone Parietal eminence Lambdoid suture Occipital bone Temporal bone, squamous part Supreme nuchal line Temporal bone, petrous part Asterion Superior nuchal line External occipital protuberance (inion) Median nuchal line (external occipital crest) Mastoid foramina Mastoid notch Temporal bone, mastoid process Temporal bone, styloid process Inferior nuchal line Vomer Occipital condyle Sphenoid bone, pterygoid process Palatine bone Mandible, ramus Mandibular foramen Maxilla, palatine process Mylohyoid groove Incisive foramen Mandible, body Submandibular fossa Mylohyoid line Digastric fossa Genial (mental) spines Clinical box 38.2 Cranial Fontanelles In the neonate, there are areas between still-growing cranial bones not occupied by bone: the fontanelles. While these regions close at different times, they have clinical implications. The posterior fontanelle provides a reference point for describing the position of the fetal head during childbirth, and the anterior fontanelle provides a potential access site for drawing cerebrospinal fluid in infants (e.g., in suspected meningitis). 544 Coronal suture Anterior fontanelle Sphenoidal fontanelle Frontal suture Squamous suture A Posterior fontanelle Lamdoid suture Sphenosquamosal Mastoid suture fontanelle Anterior fontanelle Sagittal suture Posterior fontanelle B Coronal suture Fig. 38.4 Calvaria Fig. 38.5 Structure of the calvaria Cross section. Emissary v. Scalp Outer table Diploë Dural sinus Calvaria Inner table 38 Bones of the Head Diploic vv. Dura mater Frontal bone Coronal suture Parietal bone Sagittal suture Frontal bone Parietal foramen Occipital bone Frontal crest Frontal sinus Lambdoid suture A External calvaria, superior view. Grooves for middle meningeal a. Groove for superior sagittal sinus Parietal bone Granular foveolae (for arachnoid granulations) Internal calvaria, inferior view. The interior B of the calvaria is marked by grooves for the meningeal arteries, dural venous sinuses, and arachnoid granulations (see pp. 590–591). Parietal foramen 545 Head & Neck Base of the Skull Fig. 38.6 Base of the skull: Exterior Inferior view. Revealed: Foramina and canals for blood vessels (see p. 582) and cranial nerves. Note: This view allows visual access into the posterior region of the nasal cavity. Median palatine suture Transverse palatine suture Palatine bone Palatine process Zygomatic process Maxilla Choana Zygomatic bone, temporal surface Greater palatine foramen Inferior orbital fissure Lesser palatine foramen Hamulus (of medial pterygoid plate) Vomer Pterygoid process Incisive foramen Medial plate Zygomatic arch Lateral plate Fossa of pterygoid canal Palatovaginal (pharyngeal) canal Articular tubercle Pharyngeal tubercle Foramen ovale Foramen spinosum Mandibular fossa Foramen lacerum Petrotympanic fissure Carotid canal Styloid process Occipital condyle Jugular foramen Mastoid process Stylomastoid foramen Mastoid notch (for digastric belly) Hypoglossal canal Condylar canal Foramen magnum Mastoid foramen Inferior nuchal line Parietal bone External occipital crest Superior nuchal line Supreme nuchal line 546 External occipital protuberance (inion) Fig. 38.7 Cranial fossae The interior of the skull base consists of three successive fossae that become progressively deeper in the frontal-to-occipital direction. Middle cranial fossa Anterior cranial fossa Jugum sphenoidale Lesser wing of sphenoid bone Posterior cranial fossa Dorsum sellae Middle cranial fossa Foramen magnum Petrous ridge (crest), temporal bone Posterior cranial fossa 38 Bones of the Head Anterior cranial fossa Foramen magnum A Midsagittal section, left lateral view. Fig. 38.8 Base of the skull: Interior Superior view. Chiasmatic groove Optic canal Anterior clinoid process Foramen ovale Foramen spinosum Foramen lacerum Dorsum sellae Hiatus of facial canal Clivus Petrooccipital fissure Hypoglossal canal Groove for sigmoid sinus Groove for transverse sinus B Superior view of opened skull. Frontal crest Frontal sinus Ethmoid bone, cribriform plate Ethmoid bone, crista galli Frontal bone Sphenoid bone, lesser wing Sphenoid bone, greater wing Sphenoid bone, hypophyseal fossa Posterior clinoid process Groove for lesser petrosal nerve Temporal bone, petrous part Internal acoustic meatus Jugular foramen Foramen magnum Cerebellar fossa Internal occipital crest Internal occipital protuberance Cerebral fossa 547 Head & Neck Neurovascular Pathways Exiting or Entering the Cranial Cavity Fig. 38.9 Summary of the neurovascular structures exiting or entering the cranial cavity Cribriform plate Incisive canal Olfactory n., anterior and posterior ethmoidal aa. Nasopalatine n., sphenopalatine a. Greater palatine foramen Optic canal Greater palatine n. and a. Optic n., ophthalmic a. Lesser palatine foramina Superior orbital fissure Superior ophthalmic v. Abducent n. Lacrimal n. Nasociliary n. Lesser palatine n. and a. Oculomotor n. Foramen lacerum Deep petrosal n., greater petrosal n. Frontal n. Trochlear n. Foramen spinosum Foramen rotundum Middle meningeal a., meningeal br. of mandibular n. (CN V3) Maxillary n. (CN V2) Foramen ovale Carotid canal Mandibular n. (CN V3), lesser petrosal n. accessory meningeal a. Internal carotid a., internal carotid sympathetic plexus Carotid canal Petrotympanic fissure Internal carotid a., internal carotid sympathetic plexus Anterior tympanic a., chorda tympani Foramen spinosum Stylomastoid foramen Middle meningeal a., meningeal br. of mandibular n. (CN V3) Facial n., stylomastoid a. Hiatus of canal for lesser petrosal n. Jugular foramen Lesser petrosal n., superior tympanic a. Internal jugular v. Glossopharyngeal n. Vagus n. Hiatus of canal for greater petrosal n. Accessory n. Inferior petrosal sinus Greater petrosal n. Posterior meningeal a. Internal acoustic meatus Labyrinthine a. and v. Mastoid foramen Vestibulocochlear n. Emissary v. Facial n. Hypoglossal canal Jugular foramen Sigmoid sinus Glossopharyngeal n. Vagus n. Inferior petrosal sinus Spinal v. Posterior spinal a. Accessory n. Posterior meningeal a. Anterior spinal a. Medulla oblongata Vertebral a. A Cranial cavity (interior of skull base), left side, superior view. 548 Hypoglossal n., venous plexus of hypoglossal canal Foramen magnum Accessory n. Condylar canal Condylar emissary v. B Exterior of skull base, left side, inferior view 38 Bones of the Head Fig. 38.10 Cranial nerves exiting the cranial cavity Cranial cavity (interior of skull base), right side, superior view. Removed: Brain and tentorium cerebelli. The ends of the cranial nerves have been cut to reveal the fissures, fossae, or dural cave where they pass through the cranial fossa. Olfactory bulb Olfactory fibers (filia olfactoria) (CN I) Anterior cranial fossa Olfactory tract Optic n. (CN II) Diaphragma sella Internal carotid a. Infundibular stalk Oculomotor n. (CN III) Lateral dural wall of cavernous sinus Trochlear n. (CN IV) Abducent n. (CN VI) Middle cranial fossa Trigeminal n. (CN V) Facial and vestibulocochlear nn. (CN VII, CN VIII) Glossopharyngeal n. (CN IX) Vagus n. (CN X) Accessory n. (CN XI) Inferior sagittal sinus Hypoglossal n. (CN XII) Tentorium cerebelli Posterior cranial fossa Superior sagittal sinus Tentorium cerebelli (cut) 549 Head & Neck Ethmoid & Sphenoid Bones regions: orbit (see pp. 602–603), nasal cavity (see pp. 616–617), oral cavity (see pp. 636–637), and ear (see pp. 624–625). The structurally complex ethmoid and sphenoid bones are shown here in isolation. The other bones of the skull are shown in their respective Fig. 38.11 Ethmoid bone The ethmoid bone is the central bone of the nose and paranasal air sinuses (see pp. 616–619). Crista galli Ethmoid air cells Orbital plate Middle concha Perpendicular plate Perpendicular plate Crista galli A Anterior view. Crista galli Superior concha Ethmoid bulla Cribriform plate Ethmoid air cells Orbital plate Superior view. B Ethmoid infundibulum Uncinate process Middle concha Perpendicular plate Posterior view. C Crista galli Anterior ethmoid foramen Posterior ethmoid foramen Ethmoid air cells Orbital plate (lamina papyracea) Perpendicular plate Middle concha DLeft lateral view. 550 Lesser wing Sphenoid crest Fig. 38.12 Sphenoid bone Aperture of sphenoid sinus The sphenoid bone is the most structurally complex bone in the human body. 38 Bones of the Head Orbital surface Temporal surface Superior orbital fissure Foramen rotundum Pterygoid canal Medial plate Lateral plate Pterygoid hamulus A Anterior view. Lesser wing Pterygoid process Optic canal Jugum sphenoidale Superior orbital fissure Greater wing Chiasmatic groove Foramen rotundum Anterior clinoid process Foramen ovale Foramen spinosum Hypophyseal fossa (sella turcica) Tuberculum sellae B Superior view. Lesser wing Optic canal Dorsum sellae Posterior clinoid process Posterior clinoid process Superior orbital fissure Anterior clinoid process Greater wing, cerebral surface Foramen rotundum Pterygoid canal C Posterior view. Pterygoid notch Cancellous trabeculae Dorsum sellae Medial plate Pterygoid process Lateral plate Lesser wing Sphenoid crest Aperture of sphenoid sinus Greater wing Foramen rotundum Greater wing Medial plate Pterygoid Lateral plate process Temporal surface Foramen ovale Foramen spinosum D Inferior view. Note: The vomer sits below the sphenoid crest (see p. 636). Pterygoid hamulus Superior orbital fissure Body Pterygoid fossa 551 39 Muscles of the Skull & Face Head & Neck Muscles of Facial Expression & of Mastication The muscles of the skull and face are divided into two groups. The muscles of facial expression make up the superficial muscle layer in the face. The muscles of mastication are responsible for the movement of the mandible during mastication (chewing). Fig. 39.1 Muscles of facial expression Epicranial aponeurosis (galea aponeurotica) Occipitofrontalis, frontal belly (frontalis) Corrugator supercilii Procerus Orbicularis oculi Levator labii superioris alaeque nasi Levator labii superioris alaeque nasi (O) Levator labii superioris (O) Nasalis Zygomaticus minor (O) Levator labii superioris Zygomaticus major (O) Zygomaticus minor Levator anguli oris (O) Zygomaticus major Buccinator Levator anguli oris Risorius Platysma Depressor anguli oris Risorius (I) Masseter (muscle of mastication) Orbicularis oris Depressor anguli oris (O) Depressor labii inferioris (O) Depressor labii inferioris A Anterior view. Muscle origins (O) and insertions (I) indicated on left side of face. 552 Mentalis Epicranial aponeurosis Occipitofrontalis, frontal belly (frontalis) Temporoparietalis Orbicularis oculi Anterior auricular muscle 39 Muscles of the Skull & Face Superior auricular muscle Nasalis Levator labii superioris alaeque nasi Levator labii superioris Occipitofrontalis, occipital belly (occipitalis) Zygomaticus minor Orbicularis oris Posterior auricular muscle Zygomaticus major Risorius Depressor labii inferioris Mentalis B Left lateral view. Depressor anguli oris Platysma Fig. 39.2 Muscles of mastication Left lateral view. Temporalis (cut) Temporalis Capsule of temporomandibular joint Styloid process, temporal bone Deep layer A Superficial layer. Superficial layer Masseter B Deep layer. Removed: Mandible (coronoid process) and lower temporalis. Lateral pterygoid Joint capsule of TMJ Lateral lig. of TMJ Medial pterygoid Masseter (cut) 553 Head & Neck Muscle Origins & Insertions on the Skull Fig. 39.3 Lateral skull: Origins and insertions Left lateral view. Muscle origins are shown in red, insertions in blue. Note: There are generally no bony insertions for the muscles of facial expression. These muscles insert into skin and other muscles of facial expression. Sternocleidomastoid and trapezius: Accessory n. (CN XI) Mm. of facial expression: Facial n. (CN VII) Occipitofrontalis, occipital belly Sternocleidomastoid Corrugator supercilii Trapezius Orbital part Orbicularis oculi Lacrimal part Levator labii superioris alaeque nasi Nuchal and intrinsic back mm.: Posterior rami of cervical nn. Zygomaticus major Levator labii superioris Zygomaticus minor Levator anguli oris Nasalis Semispinalis capitis Transverse part Alar part Obliquus capitis superior Depressor septi nasi Rectus capitis posterior major Orbicularis oris Buccinator Mm. of mastication: Trigeminal n., mandibular division (CN V3) Mentalis Orbicularis oris Masseter Depressor labii inferioris Lateral pterygoid Depressor anguli oris Temporalis Medial pterygoid (see Fig. 39.4) Platysma Fig. 39.4 Mandible: Origins and insertions Medial view of right hemimandible (inner surface). Muscle origins are shown in red, insertions in blue. Temporalis Lateral pterygoid Buccinator Medial pterygoid Genioglossus Suprahyoid mm. Mylohyoid Geniohyoid Digastric, anterior belly 554 Rectus capitis posterior minor Splenius capitis Longissimus capitis Fig. 39.5 Skull base: Origins and insertions Inferior view of external skull. Muscle origins are shown in red, insertions in blue. Masseter Medial pterygoid Lateral pterygoid Pharyngeal mm.: Glossopharyngeal n. (CN IX) and vagus n. (CN X) Temporalis Lingual mm.: Hypoglossal n. (CN XII) Tensor veli palatini 39 Muscles of the Skull & Face Mm. of mastication: Trigeminal n., mandibular division (CN V3) Levator veli palatini Hyoglossus (see Fig. 40.25) Stylopharyngeus Genioglossus (see Fig. 40.25) Middle pharyngeal constrictor (not shown) Styloglossus Stylohyoid Digastric, posterior belly Prevertebral mm.: Ventral cervical n. rami and cervical plexus Nuchal and intrinsic back mm.: Posterior rami of cervical nn. Rectus capitis lateralis Longus capitis Splenius capitis Rectus capitis anterior Longissimus capitis Obliquus capitis superior Sternocleidomastoid and trapezius: Accessory n. (CN XI) Rectus capitis posterior major Rectus capitis posterior minor Sternocleidomastoid Trapezius Semispinalis capitis Fig. 39.6 Hyoid bone: Origins and insertions The larynx is suspended from the hyoid bone, primarily by the thyrohyoid membrane. The hyoid bone is the site for attachment for Mylohyoid the suprahyoid and infrahyoid muscles. Muscle insertions are shown in blue. Geniohyoid Geniohyoid Stylohyoid Mylohyoid Stylohyoid Thyrohyoid Omohyoid A Anterior view. Sternohyoid Sternohyoid Omohyoid Thyrohyoid B Oblique left lateral view. 555 Head & Neck Muscle Facts (I) The muscles of facial expression originate on bone and/or fascia and insert into the subcutaneous tissue of the face. This allows them to produce their effects by pulling on the skin. Fig. 39.7 Occipitofrontalis Fig. 39.9 Muscles of the ear Anterior view. Left lateral view. ⑦ ① ⑥ ⑧ ② Fig. 39.8 Muscles of the palpebral fissure and nose Anterior view. ③ ⑤ ④ A Orbicularis oculi. Table 39.1 B Nasalis. C Levator labii superioris alaeque nasi. Muscles of facial expression: Forehead, nose, and ear Muscle Origin Insertion* Main action(s)** Epicranial aponeurosis Skin and subcutaneous tissue of eyebrows and forehead Elevates eyebrows, wrinkles skin of forehead ② Procerus Nasal bone, lateral nasal cartilage (upper part) Skin of lower forehead between eyebrows Pulls medial angle of eyebrows inferiorly, producing transverse wrinkles over bridge of nose ③ Orbicularis oculi Medial orbital margin, medial palpebral ligament, lacrimal bone Skin around margin of orbit, superior and inferior tarsal plates Acts as orbital sphincter (closes eyelids) • Palpebral portion gently closes • Orbital portion tightly closes (as in winking) ④ Nasalis Maxilla (superior region of canine ridge) Nasal cartilages Flares nostrils by drawing ala (side) of nose toward nasal septum ⑤ Levator labii superioris alaeque nasi Maxilla (frontal process) Alar cartilage of nose and upper lip Elevates upper lip, opens nostril ⑥ Anterior auricular muscle Temporal fascia (anterior portion) Helix of the ear Pulls ear superiorly and anteriorly ⑦ Superior auricular muscle Epicranial aponeurosis on side of head Upper portion of auricle Elevates ear ⑧ Posterior auricular muscle Mastoid process Convexity of concha of ear Pulls ear superiorly and posteriorly Calvaria ① Occipitofrontalis (frontal belly) Palpebral fissure and nose Ear *There are no bony insertions for the muscles of facial expression. **All muscles of facial expression are innervated by the facial nerve (CN VII) via temporal, zygomatic, buccal, mandibular, or cervical branches arising from the parotid plexus (see pp. 568–569). 556 Fig. 39.10 Muscles of the mouth G A J F A Zygomaticus major and minor, left lateral view. H B Levator labii superioris and depressor labii inferioris, left lateral view. C Levator and depressor anguli oris, left lateral view. DBuccinator, left lateral view. 39 Muscles of the Skull & Face D S K L E Orbicularis oris, anterior view. Table 39.2 F Mentalis, anterior view. Muscles of facial expression: Mouth and neck Muscle Origin Insertion* Main action(s)** Zygomatic bone (lateral surface, posterior part) Skin at corner of the mouth Pulls corner of mouth superiorly and laterally Upper lip just medial to corner of the mouth Pulls upper lip superiorly Levator labii superioris alaeque nasi (see Fig. 39.8C) Maxilla (frontal process) Alar cartilage of nose and upper lip Elevates upper lip, opens nostril ③ Levator labii superioris Maxilla (frontal process) and infraorbital region Skin of upper lip, alar cartilages of nose Elevates upper lip, dilates nostril, raises angle of the mouth ④ Depressor labii inferioris Mandible (anterior portion of oblique line) Lower lip at midline; blends with muscle from opposite side Pulls lower lip inferiorly and laterally ⑤ Levator anguli oris Maxilla (below infraorbital foramen) Skin at corner of the mouth Raises angle of mouth, helps form nasolabial furrow ⑥ Depressor anguli oris Mandible (oblique line below canine, premolar, and first molar teeth) Skin at corner of the mouth; blends with orbicularis oris Pulls angle of mouth inferiorly and laterally ⑦ Buccinator Mandible, alveolar processes of maxilla and mandible, pterygomandibular raphe Angle of mouth, orbicularis oris Presses cheek against molar teeth, working with tongue to keep food between occlusal surfaces and out of oral vestibule; expels air from oral cavity/resists distension when blowing Unilateral: Draws mouth to one side ⑧ Orbicularis oris Deep surface of skin Superiorly: maxilla (median plane) Inferiorly: mandible Mucous membrane of lips Acts as oral sphincter • Compresses and protrudes lips (e.g., when whistling, sucking, and kissing) • Resists distension (when blowing) Risorius (see pp. 552–553) Fascia over masseter Skin of corner of the mouth Retracts corner of mouth as in grimacing ⑨ Mentalis Mandible (incisive fossa) Skin of chin Elevates and protrudes lower lip Skin over lower neck and upper lateral thorax Mandible (inferior border), skin over lower face, angle of mouth Depresses and wrinkles skin of lower face and mouth; tenses skin of neck; aids in forced depression of the mandible Mouth ① Zygomaticus major ② Zygomaticus minor Neck Platysma (see pp. 552–553) *There are no bony insertions for the muscles of facial expression. **All muscles of facial expression are innervated by the facial nerve (CN VII) via temporal, zygomatic, buccal, mandibular, or cervical branches arising from its parotid plexus. 557 Head & Neck Muscle Facts (II) The muscles of mastication are located at various depths in the parotid and infratemporal regions of the face. They attach to the mandible and receive their motor innervation from the mandibular division of the trigeminal nerve (CN V3). The muscles of the oral floor that aid in ­opening the mouth are found on in Table 37.3 on p. 516. Muscles of mastication: Masseter and temporalis Table 39.3 Muscle Origin Superficial layer: zygomatic arch (anterior two thirds) ① Masseter Deep layer: zygomatic arch (posterior one third) ② Temporalis Temporal fossa (inferior temporal line) Insertion Innervation Action Mandibular angle (masseteric tuberosity) Mandibular n. (CN V3) via masseteric n. Elevates (entire muscle) and protrudes (superficial fibers) the mandible Coronoid process of mandible (apex and medial surface) Mandibular n. (CN V3) via deep temporal nn. Vertical fibers: Elevate mandible Horizontal fibers: Retract (retrude) mandible Unilateral: Lateral movement of mandible (chewing) Fig. 39.11 Masseter muscle Fig. 39.12 Temporalis muscle Left lateral view. Left lateral view. S A A Schematic. Zygomatic arch A Schematic. Frontal bone Parietal bone Masseter (deep layer) Zygomatic arch (cut) Temporalis External acoustic meatus Mastoid process Temporomandibular joint (TMJ) capsule Lateral pterygoid Styloid process Masseter (superficial layer) B Masseter with temporalis muscle. 558 Temporalis Coronoid process Lateral (temporomandibular) lig. Masseter (cut) B Temporalis muscle. Removed: Masseter and zygomatic arch. Table 39.4 Muscles of mastication: Pterygoid muscles Muscle Insertion ③ Superior head Greater wing of sphenoid bone (infratemporal crest) Temporomandibular joint (articular disk) ④ Inferior head Lateral pterygoid plate (lateral surface) Mandible (condylar process) ⑤ Superficial head Maxilla (tuberosity) Lateral pterygoid Medial pterygoid Medial surface of lateral pterygoid plate and pterygoid fossa ⑥ Deep head Pterygoid tuberosity on medial surface of the mandibular angle Innervation Action Mandibular n. (CN V3) via lateral pterygoid n. Bilateral: Protrudes mandible (pulls articular disk forward) Unilateral: Lateral movements of mandible (chewing) Mandibular n. (CN V3) via medial pterygoid n. Bilateral: Elevates mandible with masseter; contributes to protrusion. Unilateral: small grinding movements. Fig. 39.13 Lateral pterygoid muscle Superior head Inferior head Left lateral view. Zygomatic arch (cut) D Lateral pterygoid 39 Muscles of the Skull & Face Origin Articular disk Condylar head F B Left lateral pterygoid muscle. Removed: Coronoid process and part of ramus of mandible. A Schematic. Styloid process Coronoid process (cut) Fig. 39.14 Medial pterygoid muscle Left lateral view. Pterygoid process, lateral plate H Medial pterygoid (superficial head) G A Schematic. Left medial pterygoid B muscle. Removed: Coronoid process of mandible. Medial pterygoid (deep head) Mandibular angle Fig. 39.15 Masticatory muscle sling Oblique posterior view. Temporalis Articular disk D F G H A Schematic. Head of mandible Masseter Deep layer Superficial layer Superior head Inferior head Lateral pterygoid Medial pterygoid B Revealed: Muscular sling formed by the masseter and medial pterygoid muscles that elevate the mandible. 559 40 Cranial Nerves Head & Neck Cranial Nerves: Overview Fig. 40.1 Cranial nerves Inferior (basal) view. The 12 pairs of cranial nerves (CN) are numbered according to the order of their emergence from the brainstem. Note: The sensory and motor fibers of the cranial nerves enter and exit the I Olfactory n. II Optic n. brainstem at the same sites (in contrast to spinal nerves, whose sensory and motor fibers enter and leave through posterior and anterior roots, respectively). For fiber color code, see Table 40.1. III Oculomotor n. VI Abducent n. V1 V2 IV Trochlear n. V Trigeminal n. VII Facial n. VIII Vestibulocochlear n. IX Glossopharyngeal n. X Vagus n. XII Hypoglossal n. 560 XI Accessory n. V3 the cranial nerves may contain special fiber types associated with particular structures (e.g., auditory apparatus and taste buds). The cranial nerve fibers originate or terminate at specific nuclei, which are similarly classified as either general or special, somatic or visceral, and afferent or efferent. Classification of cranial nerve fibers and nuclei Table 40.1 This color coding is used in subsequent chapters to indicate fiber and nuclei classifications. Fiber type Example Fiber type Example General somatic efferent (somatomotor function) Innervate skeletal muscles General somatic afferent (somatic sensation) Conduct impulses from skin, skeletal muscle spindles General visceral efferent (visceromotor function) Innervate smooth muscle of the viscera, intraocular muscles, heart, salivary glands, etc. Special somatic afferent Conduct impulses from retina, auditory and vestibular apparatuses Special visceral efferent Innervate skeletal muscles derived from branchial arches General visceral afferent (visceral sensation) Conduct impulses from viscera, blood vessels Special visceral afferent Conduct impulses from taste buds, olfactory mucosa Fig. 40.2 Cranial nerve nuclei The sensory and motor fibers of cranial nerves III to XII originate and terminate in the brainstem at specific nuclei. Efferent (motor) nuclei Oculomotor n. nuclei (CN III) Afferent (sensory) nuclei Trigeminal n. nuclei (CN V) Nucleus of trochlear n. (CN IV) Table 40.2 40 Cranial Nerves The cranial nerves contain both afferent (sensory) and efferent (­ motor) axons that belong to either the somatic or the autonomic (visceral) nervous system (see pp. 694–695). The somatic fibers allow interaction with the environment, whereas the visceral fibers regulate the autonomic activity of internal organs. In addition to the general fiber types, Cranial nerves Cranial nerve Origin CN I: Olfactory n. Telencephalon* CN II: Optic n. Diencephalon* CN III: Oculomotor n. CN IV: Trochlear n. Functional fiber types Mesencephalon CN V: Trigeminal n. Nucleus of abducent n. (CN VI) CN VI: Abducent n. CN V Pons CN VII: Facial n. Facial nucleus (CN VII) CN VII CN VI CN VIII Salivatory nuclei CN IX CN X Nucleus ambiguus Dorsal motor (vagal) nucleus Nucleus of hypoglossal n. (CN XII) A Posterior view with the cerebellum removed. Nucleus of solitary tract CN III CN IX: Glossopharyngeal n. CN X: Vagus n. CN XII: Hypoglossal n. * The olfactory and optic nerves are extensions of the brain rather than true nerves; they are therefore not associated with nuclei in the brainstem. Visceral oculomotor nucleus Nucleus of trochlear n. (CN IV) Nucleus of oculomotor n. CN V Medulla oblongata CN XI: Accessory n. Spinal nucleus of trigeminal n. (CN V) Spinal nucleus of accessory n. (CN XI) CN VIII: Vestibulocochlear n. Mesencephalic nucleus Motor nucleus Principal (partial) sensory nucleus Inferior salivatory nucleus (CN IX) Nucleus of abducent n. (CN VI) Facial nucleus CN VII Superior salivatory nucleus Dorsal vagal nucleus (CN X) Nucleus ambiguus Nucleus of hypoglossal n. (CN XII) Nucleus of solitary tract Spinal nucleus of trigeminal n. (CN V) Midsagittal section, left lateral view. B Spinal nucleus of accessory n. (CN XI) 561 Head & Neck CN I & II: Olfactory & Optic Nerves The olfactory and optic nerves are not true peripheral nerves but ­extensions (tracts) of the telencephalon and diencephalon, respec- Olfactory tract Fig. 40.3 Olfactory nerve (CN I) Olfactory bulb Olfactory trigone Fiber bundles in the olfactory mucosa pass from the nasal cavity through the cribriform plate of the ethmoid bone into the anterior cranial fossa, where they synapse in the olfactory bulb. Axons from second-order ­afferent neurons in the olfactory bulb pass through the olfactory tract and medial or lateral olfactory stria, terminating in the cerebral cortex of the prepiriform area, in the amygdala, or in neighboring areas. Prepiriform area Medial and lateral olfactory stria Ambient gyrus tively. They are therefore not associated with cranial nerve nuclei in the brainstem. Amygdala Semilunar gyrus Diagonal stria A Olfactory bulb and tract, inferior view. Note: The amygdala and prepiriform area are deep to the basal surface of the brain. Anterior perforated substance Medullary stria of thalamus Longitudinal striae Interpeduncular nucleus Medial olfactory stria Habenular nuclei Tegmental nucleus Olfactory bulb Olfactory fibers Reticular formation Uncus, with amygdala below Dorsal longitudinal fasciculus Lateral olfactory stria Olfactory bulb (second-order sensory neurons) Frontal sinus Olfactory fibers (CN I, first-order sensory neurons) Nasal septum C Olfactory fibers. Portion of left nasal septum and lateral wall of right nasal cavity, left lateral view. 562 Olfactory mucosa Olfactory tract Cribriform plate, ethmoid bone Superior concha Nasal septum (cut) Middle concha Prepiriform area B Course of the olfactory nerve. Parasagittal section, viewed from left side. Optic tract Fig. 40.4 Optic nerve (CN II) Lateral geniculate body Lower visual field Optic radiation Upper visual field The optic nerve passes from the eyeball through the optic canal into the middle cranial fossa. The two optic nerves join below the base of the diencephalon to form the optic chiasm, before dividing into the two optic tracts. Each of these tracts divides into a lateral and medial root. Many retinal cell ganglion axons cross the midline to the contralateral side of the brain in the optic chiasm. 40 Cranial Nerves Optic n. (CN II) Lateral ventricle Striate area Optic chiasm Meyer’s loop A Optic nerve in the geniculate visual pathway, left lateral view. Optic tract Lateral geniculate body Optic n. (CN II) Thalamus Optic chiasm Optic tract Optic n. (CN II) Lateral geniculate body Optic chiasm Medial geniculate body Mesencephalon B Termination of the optic tract, left posterolateral view of the brainstem. The optic nerve contains the axons of retinal ganglion cells, which terminate mainly in the lateral geniculate body of the diencephalon and in the mesencephalon (superior colliculus). Optic radiation Occipital pole C Course of the optic nerve, inferior (basal) view. Ophthalmic n. (CN V1) Optic n. (CN II) passing through optic canal Optic chiasm Optic tract Optic canal Superior orbital fissure DOptic nerve in the left orbit, lateral view. The optic nerve exits the orbit via the optic canal. Note: The other cranial nerves (III, IV, V1, and VI) entering the orbit do so via the superior orbital fissure. 563 Head & Neck CN III, IV & VI: Oculomotor, Trochlear & Abducent Nerves Cranial nerves III, IV, and VI innervate the extraocular muscles (see p. 605). Of the three, only the oculomotor nerve (CN III) contains both somatic and visceral efferent fibers; it is also the only cranial nerve of Fig. 40.5 Nuclei of the oculomotor, trochlear, and abducent nerves emerge from the dorsal side of the brainstem and, consequently, has the longest intradural (intracranial) course of any cranial nerve. The trochlear nerve (CN IV) is the only cranial nerve in which all the fibers cross to the opposite side. It is also the only cranial nerve to Cerebral peduncles of mesencephalon Oculomotor n. (CN III) Trochlear n. (CN IV) Visceral oculomotor nucleus Nucleus of trochlear n. Cerebral aqueduct Nucleus of oculomotor n. Pons Abducent n. (CN VI) Tectum Visceral oculomotor nucleus Central gray substance Red nucleus Nucleus of abducent n. Nucleus of oculomotor n. Substantia nigra Medulla oblongata A Emergence of the cranial nerves of the extraocular muscles. Anterior view of the brainstem. Table 40.3 the extraocular muscles to innervate multiple extra- and intraocular muscles. Cerebral crus of cerebral peduncle B Oculomotor nerve nuclei. Transverse section, superior view. Cranial nerves of the extraocular muscles Course* Fibers Nuclei Function Effects of nerve injury Somatic efferent Oculomotor nucleus Innervates: • Levator palpebrae superioris • Superior, medial, and inferior rectus • Inferior oblique Visceral efferent Visceral oculomotor (Edinger-Westphal) nucleus Synapse with neurons in ciliary ganglia. Innervates: • Pupillary sphincter • Ciliary muscle Somatic efferent Nucleus of the trochlear n. Innervates: • Superior oblique • Diplopia •A ffected eye is higher and deviated medially (dominance of inferior oblique) Somatic efferent Nucleus of the abducent n. Innervates: • Lateral rectus • Diplopia •M edial strabismus (sp.) (due to unopposed action of medial rectus) Oculomotor nerve (CN III) Runs anteriorly from mesencephalon Complete oculomotor palsy (paralysis of extraand intraocular muscles): • Ptosis (drooping of eyelid) • Downward and lateral gaze deviation • Diplopia (double vision) • Mydriasis (pupil dilation) • Accommodation difficulties (ciliary paralysis) Trochlear nerve (CN IV) Emerges from posterior surface of brainstem near midline, courses anteriorly around the cerebral peduncle Abducent nerve (CN VI) Follows a long extradural path** * All three nerves enter the orbit through the superior orbital fissure; CN III and CN VI pass through the common tendinous ring of the extraocular muscles. ** The abducent nerve follows an extradural course; abducent nerve palsy may therefore develop in association with meningitis and subarachnoid hemorrhage. 564 Note: The oculomotor nerve supplies parasympathetic innervation to the intraocular muscles and somatic motor innervation to most of the extraocular muscles (also the levator palpebrae superioris). Its parasympathetic fibers synapse in the ciliary ganglion. Oculomotor nerve palsy may affect exclusively the parasympathetic or somatic fibers, or both concurrently. Short ciliary nerves Right orbit. Levator palpebrae superioris Superior rectus Trochlea Ciliary ganglion Common tendinous ring CN III Superior oblique Medial rectus 40 Cranial Nerves Fig. 40.6 Course of the nerves innervating the extraocular muscles Mesencephalon Lateral rectus (cut) Pons Inferior oblique CN IV Pontomedullary junction Internal carotid artery and plexus CN VI Lateral rectus (cut), CN VI CN III, inferior division Sympathetic root Inferior (postganglionic fibers from rectus superior cervical ganglion via internal carotid plexus) Parasympathetic root (preganglionic fibers from CN III) A Lateral view. Supraorbital n. (cut) Levator palpebrae superioris Superior ophthalmic v. Levator palpebrae superioris Superior rectus Lacrimal n. Frontal n. Trochlear n. (CN IV) Superior oblique Optic n. (CN II) Medial rectus Oculomotor n. (CN III) Superior oblique Superior rectus Medial rectus Lacrimal gland Inferior rectus Lateral rectus Trochlear n. (CN IV) Abducent n. (CN VI) Oculomotor n. (CN III) Optic n. (CN II) Inferior rectus Lateral rectus Abducent n. (CN VI) Inferior oblique B Anterior view. CN II exits the orbit via the optic canal, which lies medial to the superior orbital fissure (site of emergence of CN III, IV, and VI). C Superior view of the opened orbit. Note the relationship between the optic canal and the superior orbital fissure. 565 Head & Neck CN V: Trigeminal Nerve The trigeminal nerve, the sensory nerve of the head, has three somatic afferent nuclei: the mesencephalic nucleus, which receives proprioceptive fibers from the muscles of mastication; the principal (pontine) sensory nucleus, which chiefly mediates touch; and the spinal nucleus, which mediates pain and temperature sensation. The motor nucleus supplies motor innervation to the muscles of mastication. Fig. 40.7 Trigeminal nerve nuclei Fig. 40.8 Divisions of the trigeminal nerve (CN V) Trigeminal ganglion CN V 1 Right lateral view. Mesencephalic nucleus CN V2 Ophthalmic division (CN V1) CN V3 Trigeminal n. (CN V) Trigeminal ganglion Motor nucleus Principal (pontine) sensory nucleus Maxillary division (CN V2) Spinal nucleus Mesencephalic nucleus 4th ventricle Mandibular division (CN V3) Pons Principal sensory nucleus Motor nucleus A Anterior view of the brainstem. Trigeminal n. (CN V) B Cross section through the pons, superior view. A Table 40.4 B C Trigeminal nerve (CN V) Course Exits from the middle cranial fossa. Ophthalmic division (CN V1): Enters orbit through superior orbital fissure Maxillary division (CN V2): Enters pterygopalatine fossa through foramen rotundum Mandibular division (CN V3): Passes through foramen ovale into infratemporal fossa Fibers Nuclei Function •P rincipal (pontine) sensory nucleus of the trigeminal n. •M esencephalic nucleus of the trigeminal n. •S pinal nucleus of the trigeminal n. Innervates: • Facial skin (A) • Nasopharyngeal mucosa (B) •T ongue (anterior two thirds) (C) Involved in the corneal reflex (reflex closure of eyelid) Special visceral efferent Motor nucleus of the trigeminal n. Innervates (via CN V3): • Muscles of mastication (temporalis, masseter, medial and lateral pterygoids (D)) • Oral floor muscles (mylohyoid, anterior digastric) • Tensor tympani • Tensor veli palatini Visceral efferent pathway* • Lacrimal n. (CN V1) conveys parasympathetic fibers from CN VII along the zygomatic n. (CN V2) to the lacrimal gland • Lingual n. (CN V3) conveys parasympathetic fibers from CN VII (via the chorda tympani) to the submandibular and sublingual glands • Auriculotemporal n. (CN V3) conveys parasympathetic fibers from CN IX to the parotid gland Visceral afferent pathway* Gustatory (taste) fibers from CN VII (via chorda tympani) travel with the lingual n. (CN V3) to the anterior two thirds of the tongue Somatic afferent * Fibers of certain cranial nerves adhere to divisions or branches of the trigeminal nerve, by which they travel to their destination. ** All three divisions contribute to dural innervation in the anterior and middle cranial fossae. 566 D Effects of nerve injury • Sensory loss (traumatic nerve lesions) • Herpes zoster ophthalmicus (varicellazoster virus); herpes zoster of the face Fig. 40.9 Course of the trigeminal nerve divisions Right lateral view. Anterior ethmoidal n. Supraorbital n. Frontal n. Supratrochlear n. Superior orbital fissure Lacrimal n. (with gland) Nasociliary n. Infratrochlear n. Recurrent meningeal branch Ophthalmic division (CN V1) Long ciliary nn. Short ciliary nn. Nasociliary (sensory) root to ciliary ganglion 40 Cranial Nerves Posterior ethmoidal n. Communicating branch to zygomatic n. A Ophthalmic division (CN V1). Partially opened right orbit. Ciliary ganglion Zygomatic n. (with communicating branch) Foramen rotundum Maxillary division (CN V2) Infraorbital n. Meningeal branch Middle superior alveolar n. Ganglionic branches to pterygopalatine ganglion Anterior superior alveolar branches Pterygopalatine ganglion Posterior superior alveolar nn. B Maxillary division (CN V2). Partially opened right maxillary sinus with the zygomatic arch removed. Inferior orbital fissure Meningeal branch Trigeminal ganglion Mandibular Foramen division (CN V3) ovale Deep temporal nn. Infraorbital foramen Buccal n. Medial pterygoid nn. Auriculotemporal n. Masseteric n. Inferior dental branches Mylohyoid n. Mandibular division (CN V3). Partially C opened mandible with the zygomatic arch removed. Note: The mylohyoid nerve branches from the inferior alveolar nerve just before the mandibular foramen. Lingual n. Mandibular foramen Mental n. (in mental foramen) Inferior alveolar n. (in mandibular canal) 567 Head & Neck CN VII: Facial Nerve The facial nerve mainly conveys special visceral efferent (branchiogenic) fibers from the facial nerve nucleus to the muscles of facial expression. The other visceral efferent (parasympathetic) fibers from the superior salivatory nucleus are grouped with the visceral afferent (gustatory) fibers to form the nervus intermedius. Fig. 40.10 Facial nerve nuclei Abducent nucleus Internal genu of facial n. Nucleus of solitary tract Pons Abducent nucleus Superior salivatory nucleus Superior salivatory nucleus Facial nucleus Facial nucleus B Cross section through the pons, superior view. Nervus intermedius Geniculate ganglion Nucleus of solitary tract Stylomastoid foramen Internal acoustic meatus Geniculate ganglion Greater petrosal n. A Anterior view of the brainstem. Stapedial n. Fig. 40.11 Branches of the facial nerve Chorda tympani Right lateral view. Internal acoustic meatus Facial n. (CN VII) Stapedial n. Geniculate ganglion Hiatus of canal for greater petrosal n. Trigeminal ganglion Stylomastoid foramen CN V1 CN V2 CN V3 Greater petrosal n. Petrotympanic fissure Stylomastoid foramen Facial canal Stylohyoid Posterior auricular n. A Facial nerve in the temporal bone. 568 Lingual n. B Branches. Parotid plexus Temporal branches Tympanic membrane Chorda tympani Posterior auricular n. Pterygopalatine ganglion Parotid plexus Zygomatic branches Posterior auricular n. Buccal branches Facial n. Marginal mandibular branch Digastric, posterior belly C Parotid plexus. Cervical branch Table 40.5 Facial nerve (CN VII) Fibers Emerges in the cerebellopontine angle between the pons and olive; passes through the internal acoustic meatus into the temporal bone (petrous part), where it divides into: • Greater petrosal n. • Stapedial n. • Chorda tympani Certain special visceral efferent fibers pass through the stylomastoid foramen to the skull base, forming the intraparotid plexus Effects of nerve injury Nuclei Function Facial nucleus Innervate: • Muscles of facial expression • Stylohyoid • Digastric (posterior belly) • Stapedius Visceral efferent (parasympathetic)* Superior salivatory nucleus Synapse with neurons in the pterygopalatine or submandibular ganglion. Innervate: • Lacrimal gland • Small glands of nasal mucosa, hard and soft palate • Submandibular gland • Sublingual gland • Small salivary glands of tongue (dorsum) Special visceral afferent* Nucleus of the solitary tract Peripheral processes of fibers from geniculate ganglion form the chorda tympani (gustatory fibers from tongue) Somatic afferent Sensory fibers from the auricle, skin of the auditory canal, and outer surface of the tympanic membrane travel via CN VII to the principal sensory nucleus of the trigeminal n. Special visceral efferent Peripheral facial nerve injury: paralysis of muscles of facial expression on affected side 40 Cranial Nerves Course Associated disturbances of taste, lacrimation, salivation, hyperacusis, etc. * Grouped to form nervus intermedius, which aggregates with the visceral efferent fibers from the facial n. nucleus. Fig. 40.12 Course of the facial nerve Right lateral view. This figure shows the distribution of all the fiber types in Table 40.5. Visceral efferent (parasympathetic) and special Trigeminal n. Maxillary division Internal carotid a. with internal carotid plexus Trigeminal ganglion visceral afferent (taste) fibers shown in blue and green respectively. Postganglionic sympathetic fibers are shown in black. Lacrimal gland Via communicating br. to lacrimal n. Deep petrosal n. Geniculate ganglion Postganglionic sympathetic and parasympathetic fibers Nasal glands Superior salivatory nucleus Facial n. Nucleus of the solitary tract Mandibular division Greater petrosal n. Pterygopalatine ganglion Taste buds of soft palate Submandibular ganglion Stylomastoid foramen Parotid gland Glandular brs. Pterygoid canal with n. of pterygoid canal Sublingual gland Lingual n. Chorda tympani Submandibular gland 569 Head & Neck CN VIII: Vestibulocochlear Nerve The vestibulochochlear nerve is a special somatic afferent nerve that consists of two roots. The vestibular root transmits impulses from the vestibular apparatus; the cochlear root transmits impulses from the auditory apparatus. Fig. 40.13 Vestibulocochlear nerve: Vestibular part Fig. 40.14 Vestibulocochlear nerve: Cochlear part Flocculus of cerebellum Anterior cochlear nucleus Direct fibers to cerebellum Superior vestibular nucleus Vestibulocochlear n. (CN VIII) Vestibular root Medial vestibular nucleus Vestibular ganglion Lateral vestibular nucleus Semicircular canals Inferior vestibular nucleus Cochlear root A Anterior view of the medulla oblongata and pons with cerebellum. Superior vestibular nucleus Medial vestibular nucleus 570 Vestibulocochlear n. (CN VIII) Posterior cochlear nucleus Anterior cochlear nucleus B Cross section through the upper medulla oblongata. Table 40.6 Cochlea with spiral ganglia A Anterior view of the medulla oblongata and pons. Lateral vestibular nucleus B Cross section through the upper medulla oblongata. Vestibulocochlear nerve (CN VIII) Part Course Vestibular part Pass from the inner ear through the internal acoustic meatus to the cerebellopontine angle, where they enter the brain Cochlear part Posterior cochlear nucleus Fibers Special somatic afferent Nuclei Function Effects of nerve injury Superior, lateral, medial, and inferior vestibular nuclei Peripheral processes from the semicircular canals, saccule, and utricle pass to the vestibular ganglion and then to the four vestibular nuclei Dizziness Anterior and posterior cochlear nuclei Peripheral processes beginning at the hair cells of the organ of Corti pass to the spiral ganglion and then to the two cochlear nuclei Hearing loss Fig. 40.15 Vestibular and cochlear (spiral) ganglia Vestibular root Cochlear root Anterior ampullary n. ducts Lateral ampullary n. Utricular n. Vestibulocochlear n. (CN VIII) Superior Vestibular part Inferior ganglion part Saccular n. Fig. 40.16 Vestibulocochlear nerve in the temporal bone Posterior semicircular canal Anterior semicircular canal Spiral ganglia Cochlea Posterior ampullary n. Utricle 40 Cranial Nerves Note: The vestibular and cochlear roots are still separate structures in the petrous part of the temporal bone. Semicircular Saccule Roof of tympanic cavity (tegmen tympani) Cochlear duct Geniculate ganglion Vestibular root (CN VIII) Facial n. (CN VII) Cochlear root (CN VIII) Lateral semicircular canal Greater petrosal n. Lesser petrosal n. Oval window Semicanal of tensor tympani Internal carotid a. Sigmoid sinus (ghosted) Pharyngotympanic (auditory) tube Internal carotid plexus Posterior wall of tympanic cavity Mastoid air cells Anterior wall of tympanic cavity Chorda tympani Facial n. (in facial canal) Round window Tympanic plexus Internal jugular v. Tympanic n. Transverse crest A Medial wall of the tympanic cavity, oblique sagittal section. Greater petrosal n. Geniculate ganglion Facial n. (CN VII) Nervus intermedius (from CN VII) Internal carotid a. B Cranial nerves in the internal acoustic meatus. Posterior oblique view of the right meatus. CN VIII Cochlear n. Vestibular n. Sacculoampullary n. Utriculoampullary n. Posterior ampullary n. 571 Head & Neck CN IX: Glossopharyngeal Nerve Fig. 40.17 Glossopharyngeal nerve nuclei Nucleus of the solitary tract Inferior salivatory nucleus Superior part Inferior salivatory nucleus Nucleus ambiguus Inferior part Glossopharyngeal n. Nucleus ambiguus Superior part Nucleus of the solitary tract B Cross section through the medulla oblongata, superior view. Not shown: Nuclei of the trigeminal nerve. Inferior part Jugular foramen Superior ganglion Tympanic n. Inferior ganglion Br. to carotid sinus Br. to stylopharyngeus Pharyngeal brs. Spinal nucleus of trigeminal n. Fig. 40.18 Course of the glossopharyngeal nerve Left lateral view. Note: Fibers from the vagus nerve (CN X) combine with fibers from the glossopharyngeal nerve (CN IX) to form the pharyngeal plexus and supply the carotid sinus. A Anterior view of the medulla oblongata. Glossopharyngeal n. (CN IX) ⑤ Stylopharyngeus Vagus n. (CN X) ① Superior ganglion Inferior ganglion ④ ③ ② ⑥ Br. to carotid sinus Table 40.7 572 Glossopharyngeal nerve branches ① Tympanic n. ② Br. to carotid sinus ③ Br. to stylopharyngeus muscle ④ Tonsillar brs. ⑤ Lingual brs. ⑥ Pharyngeal brs. Pharyngeal plexus Pharyngeal brs. Carotid sinus Vagus n. (CN X) B C D E F Glossopharyngeal nerve (CN IX) Table 40.8 Course Fibers Emerges from the medulla oblongata; leaves cranial cavity through the jugular foramen Effects of nerve injury Nuclei Function Visceral efferent (parasympathetic) Inferior salivatory nucleus Parasympathetic presynaptic fibers are sent to the otic ganglion; postsynaptic fibers are distributed to • Parotid gland (A) • Buccal gland • Labial gland Special visceral efferent (branchiogenic) Nucleus ambiguus Innervate: • Constrictor muscles of the pharynx (pharyngeal branches join with the vagus nerve to form the pharyngeal plexus) • Stylopharyngeus Visceral afferent Nucleus of the solitary tract (inferior part) Receive sensory information from • Chemoreceptors in the carotid body (B) • Pressure receptors in the carotid sinus Special visceral afferent Nucleus of the solitary tract (superior part) Receives sensory information from the posterior third of the tongue (via the inferior ganglion) (C) Spinal nucleus of trigeminal nerve Peripheral processes of the intracranial superior ganglion or the extracranial inferior ganglion arise from • Tongue, soft palate, pharyngeal mucosa, and tonsils (D, E) • Mucosa of the tympanic cavity, internal surface of the tympanic membrane, pharyngotympanic tube (tympanic plexus) (F) • Skin of the external ear and auditory canal (blends with the vagus n.) Somatic afferent Fig. 40.19 Glossopharyngeal nerve in the tympanic cavity Left anterolateral view. The tympanic nerve contains visceral efferent (presynaptic parasympathetic) fibers for the otic ganglion, as well as somatic afferent fibers for the tympanic cavity and pharyngotympanic tube. It joins with sympathetic fibers from the internal carotid plexus (via the caroticotympanic nerve) to form the tympanic plexus. Tubarian br. 40 Cranial Nerves A Isolated lesions of CN IX are rare. Lesions are generally accompanied by lesions of CN X and CN XI (cranial part), as all three emerge jointly from the jugular foramen and are susceptible to injury in basal skull fractures. Fig. 40.20 Visceral efferent (parasympathetic) fibers of CN IX Tympanic n. Glossopharyngeal n. (CN IX) Trigeminal n. (CN V) Caroticotympanic n. Lesser petrosal n. Mandibular division (CN V3) Tympanic plexus Auriculotemporal n. Pharyngotympanic (auditory) tube Parotid gland Lesser petrosal n. Otic ganglion Postganglionic parasympathetic fibers (run a short distance with the auriculotemporal n.) Internal carotid plexus Tympanic canaliculus with tympanic n. Promontory of labyrinthine wall Superior ganglion Glossopharyngeal n. (CN IX) Inferior ganglion Tympanic plexus 573 Head & Neck CN X: Vagus Nerve Fig. 40.21 Vagus nerve nuclei Dorsal vagal nucleus Nucleus of the solitary tract Nucleus ambiguus Superior part Nucleus of the solitary tract Inferior part Dorsal vagal nucleus Superior part Inferior part Spinal nucleus of trigeminal n. Superior ganglion Nucleus ambiguus Inferior ganglion Olive Pharyngeal br. Jugular foramen Superior laryngeal n. Spinal nucleus of trigeminal n. A Anterior view of the medulla oblongata. Table 40.9 Course Emerges from the medulla oblongata; leaves the cranial cavity through the jugular foramen. CN X has the most extensive distribution of all the cranial nerves (vagus = “vagabond”), consisting of cranial, cervical, thoracic (see p. 87), and abdominal (see p. 215) parts. 574 Cross section through the medulla oblongata, superior view. B Vagus nerve (CN X) Fibers Nuclei Function Nucleus ambiguus Innervate: • Pharyngeal muscles (via pharyngeal plexus with CN IX) • Muscles of the soft palate • Laryngeal muscles (superior laryngeal n. supplies the cricothyroid; inferior laryngeal n. supplies all other laryngeal muscles) Dorsal vagal nucleus Synapse in prevertebral or intramural ganglia. Innervate smooth muscle and glands of • Thoracic viscera (A) • Abdominal viscera (A) Somatic afferent Spinal nucleus of trigeminal nerve Superior (jugular) ganglion receives peripheral fibers from • Dura in posterior cranial fossa (C) • Skin of ear (D), external auditory canal (E) Special visceral afferent Nucleus of solitary tract (superior part) Inferior nodose ganglion receives peripheral processes from • Taste buds on the epiglottis and root of the tongue (F) Nucleus of solitary tract (inferior part) Inferior ganglion receives peripheral processes from • Mucosa of lower pharynx at its esophageal junction (G) • Laryngeal mucosa above (superior laryngeal n.) and below (inferior laryngeal n.) the vocal fold (G) • Pressure receptors in the aortic arch (B) • Chemoreceptors in the para-aortic body (B) • Thoracic and abdominal viscera (A) Special visceral efferent (branchiogenic) Visceral efferent (parasympathetic) Visceral afferent Effects of nerve injury B The recurrent laryngeal n. supplies visceromotor innervation to the only muscle abducting the vocal cords, the posterior cricoarytenoid. Unilateral destruction of this nerve leads to hoarseness; bilateral destruction leads to respiratory distress (dyspnea). A C D E F G 40 Cranial Nerves Fig. 40.22 Course of the vagus nerve The vagus nerve gives off four major branches in the neck. The inferior laryngeal nerves are the terminal branches of the recurrent laryngeal nerves. Note: The left recurrent laryngeal nerve hooks around the aortic arch, while the right nerve hooks around the subclavian artery. Table 40.10 Vagus n. (CN X) ① Vagus nerve branches in the neck ① Pharyngeal brs. ② Superior laryngeal n. 3R Right recurrent laryngeal n. 3L Left recurrent laryngeal n. ④ Cervical cardiac brs. ② Internal br. (internal laryngeal n.) External br. (external laryngeal n.) Cricothyroid Right inferior laryngeal n. Left inferior laryngeal n. Subclavian a. 3R Brachiocephalic trunk 3L ④ Vagus n. (CN X) ① ② Internal br. (sensory) Cricothyroid Branches of the vagus nerve in the neck. Anterior view. A External br. (motor) B Innervation of the pharyngeal and laryngeal muscles. Left lateral view. 575 Head & Neck CN XI & XII: Accessory & Hypoglossal Nerves The traditional “cranial root” of the accessory nerve (CN XI), with its cell bodies found in the nucleus ambiguus, is now considered a part of the vagus nerve (CN X) that travels with the spinal root of CN XI for a short distance before splitting off. The cranial fibers are therefore part of CN X distributed via the vagus nerve after traveling briefly with the spinal root of CN XI. The spinal root fibers, arising from the spinal nucleus of the accessory nerve are now considered to be the accessory nerve, continue on as the accessory nerve (CN XI). Fig. 40.23 Accessory nerve Posterior view of the brainstem with the cerebellum removed. Note: For didactic reasons, the muscles are displayed from the right side. Jugular foramen Vagus n. (CN X) Corticobulbar fibers Nucleus ambiguus Fig. 40.24 Accessory nerve lesions Lesion of the right accessory nerve. Foramen magnum Cranial root Accessory n. (CN XI) Spinal root Sternocleidomastoid Spinal nucleus of accessory n. Trapezius B Sternocleidomastoid paralysis, right anterolateral view. See Table 40.11 (below) for clinical correlation explanation. Trapezius paralysis, posterior view. A See Table 40.11 (below) for clinical correlation explanation. Table 40.11 Accessory nerve (CN XI)* Course The spinal root emerges from the spinal cord (at the level of C1–C5/6), passes superiorly, and enters the skull through the foramen magnum, where it joins with the cranial root arising from the medulla oblongata. Both roots leave the skull through the jugular foramen. Within the jugular foramen, fibers from the cranial root pass to the vagus n. (internal branch). The spinal portion descends to the nuchal region as the external branch. Fibers Nuclei Function Effects of nerve injury Special visceral efferent Nucleus ambiguus (caudal part) Join CN X and are distributed with the recurrent laryngeal n. Innervate: • All laryngeal muscles (except cricothyroid) Spinal nucleus of accessory n. Form the external branch of the accessory n. Innervate: • Trapezius • Sternocleidomastoid Trapezius paralysis: drooping of shoulder on affected side and difficulty raising arm above horizontal plane. This paralysis is a concern during neck operations (e.g., lymph node biopsies). An injury of the accessory n. will not result in complete trapezius paralysis (the muscle is also innervated by segments C3 and C4). Sternocleidomastoid paralysis: torticollis (wry neck, i.e., difficulty turning head). Unilateral lesions cause flaccid paralysis (the muscle is supplied exclusively by the accessory n.). Bilateral lesions make it difficult to hold the head upright. Somatic efferent *See text at top of page, and Table 40.2, regarding new data on cranial fibers of CN XI. 576 Fig. 40.25 Hypoglossal nerve Precentral gyrus Corticobulbar fibers Fig. 40.26 Hypoglossal nerve nuclei 40 Cranial Nerves Posterior view of the brainstem with the cerebellum removed. Note: C1, which innervates the thyrohyoid and geniohyoid, runs briefly with the hypoglossal nerve. Styloglossus Vagus n. Note: The nucleus of the hypoglossal nerve is innervated by cortical neurons from the contralateral side. C1 Nucleus of the hypoglossal n. Hypoglossal n. (CN XII) Hypoglossal canal Hypoglossal n. Genioglossus Hyoglossus Thyrohyoid Nucleus of the hypoglossal n. Foramen magnum Hypoglossal canal C1 spinal n. Fig. 40.27 Hypoglossal nerve lesions A Anterior view. Superior view. See Table 40.12 below for clinical correlation ­explanation. Hypoglossal trigone (in rhomboid fossa) Paralyzed genioglossus Nucleus of the hypoglossal n. Normal genioglossus A muscles. Olive B Unilateral nuclear or peripheral lesion. B Cross section through the medulla oblongata. Table 40.12 Tongue Hypoglossal nerve (CN XII) Course Fibers Nuclei Function Effects of nerve injury Emerges from the medulla oblongata, leaves the cranial cavity through the hypoglossal canal, and descends laterally to the vagus nerve. CN XII enters the root of the tongue above the hyoid bone. Somatic efferent Nucleus of the hypoglossal n. Innervates: • Intrinsic and extrinsic muscles of the tongue (except the palatoglossus, supplied by CN X) Central hypoglossal paralysis (supranuclear): tongue deviates away from the side of the lesion. Nuclear or peripheral paralysis: tongue deviates toward the affected side (due to preponderance of muscle on healthy side) Flaccid paralysis: both nuclei injured; tongue cannot be protruded. 577 Head & Neck Autonomic Innervation Fig. 40.28 Parasympathetic nervous system (cranial part): Overview Ciliary ganglion There are four parasympathetic nuclei in the brainstem. The visceral efferent fibers of these nuclei travel along particular cranial nn., listed below. • Visceral oculomotor (Edinger–Westphal) nucleus: oculomotor n. (CN III) • Superior salivatory nucleus: facial n. (CN VII) • Inferior salivatory nucleus: glossopharyngeal n. (CN IX) • Dorsal vagal nucleus: vagus n. (CN X) Visceral occulomotor (EdingerWestphal) nucleus The preganglionic parasympathetic fibers often travel with multiple cranial nn. to reach their target organs. The vagus n. supplies all of the thoracic and abdominal organs as far as a point near the left colic flexure. Note: The sympathetic fibers to the head travel along the arteries to their target organs. III Submandibular ganglion Superior salivatory nucleus VII Inferior salivatory nucleus Dorsal motor nucleus of the vagus Pterygopalatine ganglion IX X Thoracic ganglia Otic ganglion Abdominal ganglia Parasympathetic preganglionic fibers Parasympathetic postganglionic fibers Table 40.13 Parasympathetic ganglia in the head Nucleus Path of presynaptic fibers Ganglion Postsynaptic fibers Target organs Edinger-Westphal nucleus Oculomotor n. (CN III) Ciliary ganglion Short ciliary nn. (CN V1) Ciliary muscle (accommodation) Pupillary sphincter (miosis) Nervus intermedius (CN VII root) → greater petrosal n. → n. of pterygoid canal Pterygopalatine ganglion • Maxillary n. (CN V2) → zygomatic n. → anastomosis → lacrimal n. (CN V1) • Orbital branches • Posterior superior nasal brs. • Nasopalatine nn. • Greater and lesser palatine nn. • Lacrimal gland • Glands of nasal cavity and paranasal sinuses • Glands of gingiva • Glands of hard and soft palate • Glands of pharynx Nervus intermedius (CN VII root) → chorda tympani → lingual n. (CN V3) Submandibular ganglion Glandular branches Submandibular gland Sublingual gland Inferior salivatory nucleus Glossopharyngeal n. (CN IX) → tympanic n. → lesser petrosal n. Otic ganglion Auriculotemporal n. (CN V3) Parotid gland Dorsal motor (vagal) nucleus Vagus n. (X) Ganglia near organs Fine fibers in organs, not individually named Thoracic and abdominal viscera Superior salivatory nucleus → = is continuous with 578 Long ciliary n. (CN V1) Pupillary dilation Accommodation Nasociliary n. (CN V1) N. of pterygoid canal Pterygoid canal 40 Cranial Nerves Ciliary ganglion Blood vessels Sweat glands Pterygopalatine ganglion Deep petrosal n. (CN VII) Vasomotor innervation Internal carotid a. plexus Facial a. plexus Superior cervical ganglion Vasomotor innervation Sympathetic postganglionic External carotid a. plexus Fig. 40.29 Sympathetic innervation of the head Sympathetic preganglionic neurons of the head originate in the lateral horn of the spinal cord (TI–T3). They exit into the sympathetic trunk and ascend to synapse in the superior cervical ganglion. Postganglionic neurons then travel with arterial plexuses. Postganglionic fibers that travel with the carotid plexus (on the internal carotid artery) join with the nasociliary nerves (of CN V1) and then the long ciliary nerves to reach the dilator pupillae muscle (pupillary dilation); other postganglionic fibers travel through the ciliary ganglion (without synapsing) to reach the ciliary muscle to participate in accomodation. Still other postganglionic fibers from the carotid plexus leave with the deep petrosal nerve, which Table 40.14 Nucleus Lateral horn of spinal cord (TI–L2) joins with the greater petrosal nerve (CN VII), to form the nerve of the pterygoid canal (vidian nerve). This nerve travels to the pterygopalatine ganglion where it distributes fibers via branches of the maxillary nerve to the glands of the nasal cavity, maxillary sinus, hard and soft palate, gingiva, and pharynx, and to sweat glands and blood vessels in the head. Postganglionic fibers from the superior cervical ganglion that travel with the facial artery plexus pass through the submandibular ganglion (without synapsing) to the submandibular and sublingual glands. Other postganglionic fibers travel with the middle meningeal plexus, through the otic ganglion (without synapsing), to the parotid gland. Sympathetic fibers in the head Path of presynaptic fibers Enter sympathetic trunk and ascend to superior cervical ganglion Ganglion Superior cervical ganglion Postsynaptic fibers Target organs ICA plexus → nasociliary n. (CN V1) → long ciliary nn. (CN V1) Dilator pupillae muscle (mydriasis) Postganglionic fibers → ciliary ganglion*→ short ciliary nn. (limited number of fibers) Ciliary muscle (sparse sympathetic fibers contributing to accommodation) ICA plexus → deep petrosal n. → n. of pterygoid canal → pterygopalatine ganglion* → branches of maxillary n. (CN V2) Glands of nasal cavity Sweat glands Blood vessels Facial a. plexus → submandibular ganglion* Submandibular gland Sublingual gland External carotid a. plexus Parotid gland *passes through without synpasing; → = is continuous with ICA, internal carotid a. 579 41 Neurovasculature of the Skull & Face Head & Neck Innervation of the Face Fig. 41.1 Motor innervation of the face Left lateral view. Five branches of the facial nerve (CN VII) provide motor innervation to the muscles of facial expression. The mandibular division of the trigeminal nerve (CN V3) supplies motor innervation to the muscles of mastication. Temporal brs. Parotid plexus Zygomatic brs. Posterior auricular n. Buccal brs. Facial n. (CN VII) Marginal mandibular br. Cervical br. A Motor innervation of the muscles of facial expression. Maxillary division (CN V2) Mandibular division (CN V3, exits via foramen ovale) Trigeminal ganglion Ophthalmic division (CN V1) Trigeminal n. (CN V) Meningeal br. Deep temporal nn. (to temporalis)* N. to lateral pterygoid and lateral pterygoid* Buccinator Inferior alveolar n. Auriculotemporal n. Buccal n. Parotid brs. Lingual n. N. to masseter and masseter* N. to medial pterygoid and medial pterygoid* B Motor innervation of the muscles of mastication (*). 580 Fig. 41.2 Sensory innervation of the face Trigeminal n. (CN V) Infraorbital n. (from CN V2) Greater occipital n. (C2), posterior ramus Maxillary division Spinal nn., posterior rami Mandibular division Transverse cervical n. Mental n. (from CN V3) Lesser occipital n. (C2) anterior ramus Supraclavicular nn. Great auricular n. (C2, C3), anterior rami A Sensory branches of the trigeminal nerve, anterior view. The sensory branches of the three divisions emerge from the supraorbital, infraorbital, and mental foramina, respectively. Maxillary division (CN V2)* B Cutaneous innervation of the head and neck, left lateral view. The occiput and nuchal regions are supplied by the posterior rami (blue) of the spinal nerves (the greater occipital nerve is the posterior ramus of C2). 41 Neurovasculature of the Skull & Face Ophthalmic division Supraorbital n. (from CN V1) Ophthalmic division (CN V1)* Supraorbital n.* Supratrochlear n.* Trigeminal ganglion Pterygopalatine ganglion Mandibular division (CN V3) Infraorbital n.* Auriculotemporal n.* Masseteric n. Buccal n.* Lingual n.* Inferior alveolar n.* Mental n.* Mylohyoid n. C Divisions of the trigeminal nerve, left lateral view. *Indicates sensory nn. 581 Head & Neck Arteries of the Head & Neck chiefly supplies the brain (p. 688), although its branches anastomose with the external carotid in the orbit and nasal septum. The external carotid is the major supplier of structures of the head and neck. The head and neck are supplied by branches of the common carotid artery. The common carotid splits at the carotid bifurcation into two branches: the internal and external carotid arteries. The internal carotid Supraorbital a. Fig. 41.3 Internal carotid artery Supratrochlear a. Left lateral view. The most important extracerebral branch of the internal carotid artery is the ophthalmic artery, which supplies the upper nasal septum (p. 620) and the orbit (p. 608). See pp. 688–689 for the arteries of the brain. Ophthalmic a. Posterior communicating a. Internal carotid a. Dorsal nasal a. Basilar a. Posterior ethmoidal a. External carotid a. Ophthalmic a. Internal carotid a. Angular a. Internal carotid a. External carotid a. Facial a. Common carotid a. Superior thyroid a. Vertebral a. Subclavian a. Vertebral a. Schematic. A Ophthalmic a. Anterior cerebral a. Subclavian a. Middle cerebral a. Anterior choroidal a. Posterior communicating a. Superior hypophyseal a. Basal tentorial br. Cerebral part Marginal tentorial br. Cavernous part Inferior hypophyseal a. Trigeminal ganglion br. Neural br. Meningeal br. Cavernous sinus br. A. of pterygoid canal Parts and branches of the internal carotid B artery. 582 Carotid bifurcation Petrous part Caroticotympanic aa. Cervical part Course of the internal carotid artery. C Clinical box 41.1 The carotid artery is often affected by atherosclerosis, a hardening of arterial walls due to plaque formation. The examiner can determine the status of the arteries using ultrasound. Note: The absence of atherosclerosis in the carotid A Common carotid artery with “normal” flow. artery does not preclude coronary heart disease or atherosclerotic changes in other locations. B Calcified plaque in the carotid bulb. 41 Neurovasculature of the Skull & Face Carotid artery atherosclerosis Fig. 41.4 External carotid artery: Overview Left lateral view. Terminal branches Posterior branches Angular a. Medial branch Anterior branches A Schematic of the external carotid artery. Superficial temporal a. Posterior auricular a. Superior labial a. Maxillary a. Occipital a. Ascending pharyngeal a. Inferior labial a. Facial a. Facial a. Table 41.1 Group Branches of the external carotid artery Artery Superior thyroid a. Anterior (p. 584) Lingual a. Medial (p. 584) Ascending pharyngeal a. Facial a. Posterior (p. 585) Terminal (p. 585) Occipital a. Internal carotid a. Lingual a. Carotid bifurcation with carotid body Superior thyroid a. Superior laryngeal a. Vertebral a. External carotid a. Left common carotid a. Thyrocervical a. Left subclavian a. Posterior auricular a. Maxillary a. Superficial temporal a. B Course of the external carotid artery. 583 Head & Neck External Carotid Artery: Anterior, Medial & Posterior Branches Fig. 41.5 Anterior and medial branches Ophthalmic a. Left lateral view. The arteries of the anterior aspect supply the anterior structures of the head and neck, including the orbit (p. 606), ear (p. 632), larynx (p. 530), pharynx (p. 654), and oral cavity. Note: The angular artery anastomoses with the dorsal nasal artery of the internal carotid (via the ophthalmic artery). Angular a. Internal carotid a. Ascending pharyngeal a. Facial a. Lingual a. Superior thyroid a. A Arteries of the anterior and medial branches. The copious blood supply to the face makes facial injuries bleed profusely but heal quickly. There are extensive anastomoses ­between branches of the external carotid ­artery and between the external carotid artery and branches of the ophthalmic artery. Dorsal nasal a.* Angular a. Superficial temporal a. Infraorbital a. Maxillary a. Superior labial a. Ascending pharyngeal a. Tonsillar a. Ascending palatine a. Inferior labial a. Facial a. Mental a. Lingual a. Internal carotid a. Submental a. Glandular branches Left common carotid a. Superior thyroid a. B Course of the anterior and medial branches. 584 *Branch of ophthalmic a. Fig. 41.6 Posterior branches Superficial temporal a. Posterior auricular a. Occipital a. External carotid a. Vertebral a. Left common carotid a. A Arteries of the posterior branch. Posterior branch Occipital branches Superficial temporal a. 41 Neurovasculature of the Skull & Face Left lateral view. The posterior branches of the external carotid artery supply the ear (p. 632), posterior skull (p. 594), and posterior neck muscles (p. 541). Occipital a. Descending branch Maxillary a. Posterior auricular a. Ascending pharyngeal a. Occipital a. Facial a. Lingual a. Internal carotid a. Superior thyroid a. Table 41.2 Branch Anterior brs. Medial br. Posterior brs. External carotid a. Left common carotid a. B Course of the posterior branches. Anterior, medial, and posterior branches of the external carotid artery Artery Divisions and distribution Superior thyroid a. Glandular br. (to thyroid gland); superior laryngeal a.; sternocleidomastoid br. Lingual a. Dorsal lingual brs. (to base of tongue, palatoglossal arch, tonsil, soft palate and epiglottis); sublingual a. (to sublingual gland, tongue, oral floor, oral cavity); sublingual br. to the sublingual gland; deep lingual a. Facial a. Ascending palatine a. (to pharyngeal wall, soft palate, pharyngotympanic tube); tonsillar branch (to palatine tonsils); submental a. (to oral floor, submandibular gland); labial aa.; angular a. (to nasal root) Ascending pharyngeal a. Pharyngeal brs.; inferior tympanic a. (to mucosa of inner ear); posterior meningeal a. Occipital a. Occipital brs.; descending br. (to posterior neck muscles) Posterior auricular a. Stylomastoid a. (to facial n. in facial canal); posterior tympanic a.; auricular br.; occipital br.; parotid br. For terminal brs., see Table 41.3 (p. 586). 585 Head & Neck External Carotid Artery: Terminal Branches The terminal branches of the external carotid artery consist of two major arteries: superficial temporal and maxillary. The superficial temporal artery supplies the lateral skull. The maxillary artery is a major artery for internal structures of the face. Fig. 41.7 Superficial temporal artery Left lateral view. Inflammation of the superficial temporal artery due to temporal arteritis can cause severe headaches. The course of the frontal branch of the artery can often be seen superficially under the skin of elderly patients. Parietal bone br. Frontal br. Superficial temporal a. Maxillary a. External carotid a. Middle temporal a. Zygomaticoorbital a. Transverse facial a. Left common carotid a. Superficial temporal a. Maxillary a. External carotid a. A Arteries of the terminal branch. Table 41.3 Branch External carotid a. B Course of the superficial temporal artery. Terminal branches of the external carotid artery Artery Divisions and distribution Superficial temporal a. Transverse facial a. (to soft tissues below the zygomatic arch); frontal brs.; parietal brs.; zygomatico-orbital a. (to lateral orbital wall) Mandibular part Inferior alveolar a. (to mandible, teeth, gingiva); middle meningeal a.; deep auricular a. (to temporomandibular joint, external auditory canal); anterior tympanic a. Pterygoid part Masseteric a.; deep temporal brs.; pterygoid brs.; buccal a. Posterosuperior alveolar a. (to maxillary molars, maxillary sinus, gingiva); infraorbital a. (to maxillary alveoli) Maxillary a. Pterygopalatine part Descending palatine a. Sphenopalatine a. * Parts not shown here. See Fig 41.27 (p. 599) and Table 41.8 (p. 601). 586 Greater palatine a. (to hard palate) Lesser palatine a. (to soft palate, palatine tonsil, pharyngeal wall) Lateral posterior nasal aa. (to lateral wall of nasal cavity, conchae) Posterior septal brs. (to nasal septum) Fig. 41.8 Maxillary artery Left lateral view. The maxillary artery consists of three parts: mandibular (blue), pterygoid (green), and pterygopalatine (yellow). Clinical box 41.2 The middle meningeal artery supplies the meninges and overlying calvaria. Rupture of the artery (generally due to head trauma) results in an epidural hematoma. Middle meningeal a. Posterior superior alveolar a. Frontal br. Anastomotic br. with lacrimal a. Parietal br. Deep auricular a. Buccal a. Anterior tympanic a. 41 Neurovasculature of the Skull & Face Middle meningeal artery Inferior alveolar a. A Divisions of the maxillary artery. Middle meningeal a. Petrous br. A Right middle meningeal artery, medial view of opened skull. Calvaria Infraorbital a. Ruptured middle meningeal a. Sphenopalatine a. Deep temporal aa. Pterygoid br. Fracture Epidural B hematoma. Schematic ­coronal section. Arachnoid Dura mater Epidural hematoma Sphenopalatine artery Middle meningeal a. Maxillary a. Masseteric a. Buccal a. Mylohyoid br. Mental br. The sphenopalatine artery supplies the wall of the nasal cavity. Excessive nasopharyngeal bleeding from the branches of the sphenopalatine artery may necessitate ligation of the maxillary artery in the pterygopalatine fossa. Lateral posterior nasal aa. Posterior septal brs. Inferior alveolar a. Sphenopalatine a. Anterior and posterior superior alveolar aa. Descending palatine a. B Course of the maxillary artery. Lesser palatine a. Greater palatine a. Lateral wall of right nasal cavity, medial view. C 587 Head & Neck Veins of the Head & Neck Fig. 41.9 Veins of the head and neck Left lateral view. The veins of the head and neck drain into the brachiocephalic vein. Note: The left and right brachiocephalic veins are not symmetrical. Superior sagittal sinus Table 41.4 Principal superficial veins Vein Region drained Location Internal jugular v. Interior of skull (including brain) Within carotid sheath External jugular v. Superficial head Anterior jugular v. Neck, portions of head Within superficial cervical fascia Superficial temporal v. Confluence of the sinuses Cavernous sinus Transverse sinus Sigmoid sinus External Facial v. Internal Supraorbital v. Jugular vv. Anterior Suprascapular v. Left brachiocephalic v. Subclavian v. Supratrochlear v. A Principal veins of the head and neck. Superior and inferior ophthalmic vv. Superficial temporal v. Pterygoid plexus (deep temporal vv.) Angular v. Maxillary v. Occipital v. Posterior auricular v. Facial v. Retromandibular v. Inferior labial v. Superior thyroid v. Submental v. Internal jugular v. External jugular v. Anterior jugular v. B Superficial veins of the head and neck. Note: The course of the veins is highly variable. 588 Left brachiocephalic v. Suprascapular v. Subclavian v. Fig. 41.10 Deep veins of the head Deep Cavernous temporal vv. sinus Superior and inferior petrosal sinuses Angular v. Sigmoid sinus Deep facial v. Superficial temporal v. Pterygoid plexus Maxillary v. Retromandibular v. 41 Neurovasculature of the Skull & Face Superior ophthalmic v. Left lateral view. Removed: Upper ramus, condylar and coronoid processes of mandible. The pterygoid plexus is a venous network situated between the mandibular ramus and the muscles of mastication. The cavernous sinus connects branches of the facial vein to the sigmoid sinuses. Retromandibular v. posterior division Internal jugular v. Retromandibular v. anterior division Facial v. External palatine v. Parietal emissary v. Superior sagittal sinus Fig. 41.11 Veins of the occiput Confluence of the sinuses Occipital emissary v. Posterior view. The superficial veins of the occiput communicate with the dural venous sinuses via emissary veins that drain to diploic veins (calvaria, p. 545). Note: The external vertebral venous plexus traverses the entire length of the spine (p. 45). Transverse sinus External occipital protruberance Sigmoid sinus Venous plexus around foramen magnum Mastoid emissary v. Condylar emissary v. Internal jugular v. Occipital v. External vertebral venous plexus Table 41.5 Venous anastomoses The extensive venous anastomoses in this region provide routes for the spread of infections. Extracranial vein Connecting vein Venous sinus Angular v. Superior and inferior ophthalmic vv. Vv. of palatine tonsil Pterygoid plexus; inferior ophthalmic v. Superficial temporal v. Parietal emissary vv. Superior sagittal sinus Occipital v. Occipital emissary v. Transverse sinus, confluence of the sinuses Posterior auricular v. Mastoid emissary v. External vertebral venous plexus Condylar emissary v. Cavernous sinus* Sigmoid sinus *Deep spread of bacterial infection from the facial region may result in cavernous sinus thrombosis. 589 Head & Neck Meninges The brain and spinal cord are covered by membranes called meninges. The meninges are composed of three layers: dura mater (dura), arachnoid mater (arachnoid membrane), and pia mater. The subarachnoid space, located between the arachnoid mater and pia mater, contains cerebrospinal fluid (CSF, see p. 684). See p. 40 for the coverings of the spinal cord. Diploic vv. Fig. 41.12 Layers of the meninges See pp. 686–687 for the veins of the brain. Epidural hematoma Cranial bone Dura mater (cut) Cranial bone Neurothelium Dura mater Arachnoid Outer table Subdural hemorrhage Arachnoid trabeculae Diploë Inner table Cerebral cortex Pia mater Superior sagittal sinus Superior cerebral vv. Arachnoid mater Cerebral a. Subarachnoid space Cerebral v. A Coronal section through the meninges, anterior view. Middle cerebral a. (branches) Lateral lacuna (opened) Pia mater (on cerebral surface) Arachnoid granulations (arachnoid villi) Bridging vv. Confluence of the sinuses Superior view of opened cranium. Left side: Dura mater (outer layer) B cut to reveal arachnoid (middle layer). Right side: Dura mater and arachnoid removed to reveal pia mater (inner layer) lining the surface of the brain. Note: Arachnoid granulations, sites for reabsorption of cerebrospinal fluid into the venous blood, are protrusions of the arachnoid layer of the meninges into the venous sinus system. Fig. 41.13 Dural folds (septa) Left anterior oblique view. Two layers of meningeal dura come together, after separating from the periosteal dura during formation of a dural (venous) sinus, to form a dural fold or septum. These include the falx cerebri (separating right and left cerebral hemispheres); the tentorium cerebelli (supporting the cerebrum to keep it from crushing the underlying cerebellum); the falx cerebelli (not shown, separating right and left cerebellar lobes under the tentorium); and the diaphragma sellae (forming the roof over the hypophyseal fossa and invaginated by the hypophysis). 590 Ostia of bridging vv. Falx cerebri Diaphragma sellae Crista galli Optic n. Internal carotid a. Tentorial notch Tentorium cerebelli Clinical box 41.3 Bleeding between the bony calvarium and the soft tissue of the brain (extracerebral hemorrhage) exerts pressure on the brain. A rise of intracranial pressure may damage brain tissue both at the bleeding site and in more Bridging v. Ruptured middle meningeal a. Subarachnoid space remote brain areas. Three types of intracranial hemorrhage are distinguished based on the relationship to the dura mater. See pp. 688–689 for the arteries and pp. 686–687 for the veins of the brain. Superior sagittal sinus Falx cerebri Dura mater Inferior sagittal sinus Calvaria Ruptured aneurysm Sphenoid sinus A Epidural hematoma (above the dura). B Subdural hematoma (below the dura). C Subarachnoid hemorrhage. 41 Neurovasculature of the Skull & Face Extracerebral hemorrhages Fig. 41.14 Arteries of the dura mater Midsagittal section, left lateral view. See pp. 688–689 for the arteries of the brain. Middle meningeal a. (frontal br.) Middle meningeal a. (parietal br.) Fig. 41.15 Innervation of the dura mater Superior view. Removed: Tentorium cerebelli (right side). Occipital a. (mastoid br.) Middle meningeal a. Vertebral a. (via foramen spinosum) (brs.) Cribriform plate Anterior and posterior ethmoidal nn. (meningeal brs.) CN V1, V2, and V3 (meningeal brs.) CN V3 (meningeal br.) Ist and 2nd cervical nn. (meningeal brs.) CN X (meningeal brs.) CN V1 and V2 (tentorial brs.) Tentorium cerebelli 591 Head & Neck Dural Sinuses The dura mater is composed of two layers that separate in the region of a venous sinus into an outer periosteal layer, which lines the calvaria and an inner meningeal layer, which forms the unattached boundaries of the sinus. In the region of a sinus, the two meningeal dural layers come together after forming the sinus to create a dural fold, or septa (see Fig. 41.13, p. 590). The network of venous sinuses collect blood from the scalp, the calvaria, and the brain and eventually drain into the internal jugular vein at the jugular foramen. Fig. 41.16 Formation of a dural sinus Superior sagittal sinus Dura mater Periosteal layer Meningeal layer Dura mater Outer table Cranial bone Diploë Inner table Galea aponeurotica Emissary v. Scalp vv. Scalp Lateral lacuna (closed) Granular foveola Outer table Pia mater (on cerebral surface) Superior cerebral vv. Superior sagittal sinus Diploë Inner table Middle cerebral a. (brs.) Lateral lacuna (open) Lateral lacuna with arachnoid granulations Falx cerebri Bridging v. Arachnoid granulations (arachnoid villi) Superior cerebral vv. Bridging vv. A Structure of a dural sinus. Superior sagittal sinus, coronal section, anterior view. Ö Falx cerebri K D Y Ä F H Table 41.6 Tentorium cerebelli G Fig. 41.17 Dural sinuses in the cranial cavity Superior view of opened cranial cavity. Dural sinus system ghosted in blue. Removed: Tentorium cerebelli (right side). Lower group Sphenoparietal sinus Anterior sinus Cavernous sinus Venous plexus of foramen ovale ⑨ Superior sagittal sinus ⑦ Cavernous sinus Basilar plexus ② Inferior sagittal sinus ⑧ Anterior intercavernous sinus ⑫ petrosal sinus ③ Straight sinus ⑨ Posterior intercavernous sinus ④ Confluence of the sinuses ⑩ Sphenoparietal sinus ⑤ Transverse sinus ⑪ Superior petrosal sinus ⑥ Sigmoid sinus ⑫ Inferior petrosal sinus ⑩ ⑦ Petrosquamous sinus Middle meningeal v. Superior petrosal sinus Jugular foramen Posterior intercavernous sinus ① The occipital sinus is also included in the upper group (see Fig. 49.1, p. 686). Superior ophthalmic v. ⑧ intercavernous Principal dural sinuses Upper group 592 B Superior sagittal sinus in situ. Superior view of opened cranial cavity. The roof of the sinus (the periosteal layer of the dura attached to the calvaria) is removed. Left side: Areas of dura mater removed to show arachnoid granulations (protrusions of the arachnoid layer of the meninges) in the sinus. Right side: Dura mater and arachnoid layers removed to reveal pia mater adhering to the cerebral cortex. S A J L Confluence of the sinuses Inferior Sigmoid ⑥ sinus Great cerebral v. Marginal sinus Inferior cerebral vv. Occipital sinus Transverse sinus Tentorium cerebelli ③ Straight sinus Confluence of the sinuses ④ Superior sagittal sinus ① ⑤ ⑪ Fig. 41.18 Cavernous sinus and cranial nerves Internal carotid a. Optic chiasm (optic n., CN II) Oculomotor n. (CN III) A Superior view of the right anterior and middle cranial fossae. Removed: Lateral dural wall and roof of the cavernous sinus. The trigeminal ganglion is cut and retracted laterally following removal of its dural covering Trochlear n. (CN IV) Internal carotid a. Cavernous sinus Abducent n. (CN VI) Motor root Sensory root Middle cranial fossa Trigeminal nerve (CN V) Anterior clinoid process B Topography of the extradural course of the abducent nerve along the clivus and in the left cavernous sinus. Left lateral view. Note the long extradural path the abducent nerve follows along the clivus. It runs within the subarachnoid space, pierces the dura mater, passes under Gruber’s ligament through Dorello’s canal and enters the cavernous sinus at the tip of the petrous temporal bone (at the junction of the middle and posterior cranial fossae). It courses through the cavernous sinus lateral to the internal carotid artery to reach the orbit through the superior orbital fissure. Trigeminal ganglion Posterior clinoid process Hypophyseal fossa Clivus Dorello's canal Ophthalamic a. Internal carotid a. Carotid siphon Ophthalmic n. (CN V1) Trochlear n. (CN IV) Gruber's lig. Oculomotor n. (CN III) Abducent n. (CN VI) Maxillary n. (CN V2) Trigeminal n. (CN V) Trigeminal ganglion Fig. 41.19 Cavernous sinus, coronal section through middle cranial fossa Anterior view. The right and left cavernous sinuses connect via the intercavernous sinuses that pass around the hypophysis, which sits in the hypophyseal fossa after invaginating the diaphragma sellae. On each side, this coronal section cuts through the internal carotid artery twice due to Optic n. Hypophysis 41 Neurovasculature of the Skull & Face Ophthalmic a. the presence of the carotid siphon, a 180 degree bend in the cavernous part of the artery. Of the five cranial nerves, or their divisions, associated with the sinus only the abducent nerve (CN VI) is not embedded in the lateral dural wall. Internal carotid a. Oculomotor n. (CN III) Trochlear n. (CN IV) Abducent n. (CN VI) Ophthalmic n. (CN V1) Cavernous sinus Sphenoid sinus Maxillary n. (CN V2) 593 Head & Neck Topography of the Superficial Face Fig. 41.20 Superficial neurovasculature of the face Anterior view. Removed: Skin and fatty subcutaneous tissue; muscles of facial expression (left side). Supratrochlear n. Supraorbital n., medial and lateral brs. Superficial temporal a. and v., auriculotemporal n. Dorsal nasal a. Facial n., temporal brs. Auriculotemporal n. Angular a. and v. Superficial temporal a. and v. Infraorbital a. and n. (in infraorbital foramen) Transverse facial a. Facial n., zygomatic brs. Facial n., buccal brs. Zygomaticus major Parotid gland Parotid duct Superior labial a. Facial n., marginal mandibular br. Facial a. and v. Inferior labial a. 594 Masseter Inferior alveolar a., mental br. Mental n. (in mental foramen) Fig. 41.21 Superficial neurovasculature of the head Left lateral view. Superficial temporal a. and v. 41 Neurovasculature of the Skull & Face Superficial temporal a., frontal br. Superficial temporal a., parietal br. Supraorbital n. (CN V1) Supratrochlear n. (CN V1) Zygomaticoorbital a. Auriculotemporal n. (CN V3) Infratrochlear n. (CN V1) Angular v. External nasal n. (CN V1) Transverse facial a. Infraorbital n. (CN V2) Occipital a. Parotid duct Greater occipital n. (C2, posterior ramus) Buccinator Lesser occipital n. (from cervical plexus [C2]) Sternocleidomastoid Mental n. (CN V3) Posterior auricular v. Parotid gland Facial v. Masseter Brs. of parotid plexus of facial n. Retromandibular v., posterior division External jugular v. Great auricular n. (from cervical plexus [C2–C3]) 595 Head & Neck Topography of the Parotid Region & Temporal Fossa Fig. 41.22 Parotid region Left lateral view. Removed: Parotid gland, sternocleidomastoid, and veins of the head. Revealed: Parotid bed and carotid triangle. Superficial temporal a., frontal and parietal brs. Superior (temporofacial) trunk Supraorbital n. (CN V1) Supratrochlear n. (CN V1) Auriculotemporal n. (CN V3) Infratrochlear n. (CN V1) Temporal brs. of parotid plexus (CN VII) External nasal n. (CN V1) Infraorbital n. (CN V2) Occipital a. Greater occipital n. (posterior ramus of C2) Zygomatic brs. of parotid plexus (CN VII) Posterior auricular n. (CN VII) Parotid duct Buccal brs. of parotid plexus (CN VII) Lesser occipital n. (cervical plexus [C2]) Sternocleidomastoid Mental n. (CN V3) N. to digastric, posterior belly (CN VII) N. to stylohyoid (CN VII) Masseter Marginal mandibular br. of parotid plexus (CN VII) 596 Inferior Cervical Intraparotid (cervicofacial) plexus of the br. of trunk parotid plexus facial n. (CN VII) (CN VII) External jugular v. Great auricular n. (cervical plexus [C2–C3]) Fig. 41.23 Temporal fossa Temporal fossa (shaded) Superior temporal line Inferior temporal line Frontal bone, zygomatic process Zygomatic bone, frontal process Supramastoid crest Zygomatic bone Zygomatic arch (cut) Infratemporal fossa (deep to ramus of mandible) 41 Neurovasculature of the Skull & Face Left lateral view. The temporal fossa is located on the lateral aspect of the skull. It communicates with the infratemporal fossa inferiorly (medial to the zygomatic arch). The main component of the fossa is the large temporalis muscle. Coronoid process (in temporal fossa) Fig. 41.24 Temporal fossa Left lateral view. Removed: Sternocleidomastoid and masseter. Revealed: Temporal fossa and temporomandibular joint (p. 638). Temporomandibular joint capsule Zygomatic arch Temporalis Coronoid process Facial n. Parotid duct (cut) Masseter Hypoglossal n. Superior cervical ganglion Submandibular gland, superficial part 597 Head & Neck Topography of the Infratemporal Fossa Fig. 41.25 Bony boundaries of Infratemoral fossa Inferior orbital fissure Sphenopalatine foramen Temporal bone, zygomatic process Oblique external view of base of the skull. Temporal bone, squamous part Mandibular fossa Articular eminence External acoustic meatus Foramen spinosum Foramen ovale Infratemporal surface of maxilla Lateral pterygoid plate Maxillary tuberosity Medial pterygoid plate Palatine bone, pyramidal process Occipital condyle Pterygoid hamulus Foramen magnum Maxilla, palatine process Palatine bar, maxillary process Pterygomaxillary fissure Fig. 41.26 Infratemporal fossa: Superficial dissection Left lateral view. Removed: Ramus of mandible. Note: The mylohyoid nerve (see Fig. 45.15 and 45.17A) branches from the inferior alveolar nerve just before the mandibular foramen. Temporalis (cut) Superficial temporal a. and v. Deep temporal nn. Superior alveolar nn. posterior superior alveolar br. (CN V2) Maxillary a. Posterior superior alveolar a. Buccal n. and a. Medial pterygoid, superficial and deep heads Lingual n. Mandibular canal Facial a. and v. Deep temporal aa. Auriculotemporal n. Lateral pterygoid, superior and inferior heads Facial n. (CN VII) Ramus of mandible (cut) Inferior alveolar n. Sternocleidomastoid Masseter (cut) Retromandibular v., posterior division 598 Left lateral view. Removed: Lateral pterygoid muscle (both heads). Revealed: Deep infratemporal fossa and mandibular nerve as it enters the mandibular canal via the foramen ovale in the roof of the fossa. Temporalis (cut) Superficial temporal a. and v. Deep temporal n. Lateral pterygoid (cut) Sphenopalatine a. Mandibular n. (CN V3) Posterior superior alveolar a. Middle meningeal a. Buccal a. and n. 41 Neurovasculature of the Skull & Face Fig. 41.27 Infratemporal fossa: Deep dissection Auriculotemporal n. Maxillary a. Buccinator Medial pterygoid, superficial head Lingual n. Sphenomandibular lig. Facial n. Medial pterygoid, deep head Mylohyoid n. Facial a. and v. Inferior alveolar a. and n. Masseter 599 Head & Neck Neurovasculature of the Infratemporal Fossa Fig. 41.28 Mandibular nerve (CN V3) in the infratemporal fossa Mandibular division (CN V3) Meningeal br. Masseteric n. Deep temporal nn. Auriculotemporal n. Lateral pterygoid n. Parotid brs. Medial pterygoid n. Inferior alveolar n. Buccal n. Mandibular division (CN V3) Lingual n. N. of tensor tympani (with muscle) Foramen ovale N. of tensor veli palatini (with muscle) Facial n. Stylomastoid foramen A Left lateral view. Lesser petrosal n. Auriculotemporal n. Medial pterygoid n. Communicating br. to auriculotemporal n. Otic ganglion Chorda tympani Lingual n. Mylohyoid n. Inferior alveolar n. Left medial view. B Table 41.7 Nerves of the infratemporal fossa Nerve Nerve Fibers Distribution Muscular Branches (CN V3) Branchial motor Muscles of mastication; mylohyoid; tensor tympani; tensor veli palatini, anterior belly of digastric Auriculotemzporal (CN V3) General sensory Auricle, temporal region, and temporomandibular joint Visceral motor from glossopharyngeal n. (CN IX) Parotid gland Inferior alveolar (CN V3) General sensory Mandibular teeth; mental branch supplies skin of lower lip and chin Lingual (CN V3) General sensory Anterior two thirds of tongue, floor of mouth Buccal (CN V3) General sensory Skin and mucous membrane of cheek Meningeal (CN V3) General sensory Dura of middle cranial fossa Special sensory taste Anterior two thirds of tongue Visceral motor Submandibular and sublingual glands via submandibular ganglion and lingual n (CN V3) Chorda tympani (CN VII) 600 Mylohyoid n. 41 Neurovasculature of the Skull & Face Fig. 41.29 Arteries in the infratemporal fossa Left lateral view into area. The maxillary artery passes either superficial or deep to the lateral pterygoid in the infratemporal fossa (see Fig. 41.27, p. 599) and passes medially into the pterygopalatine fossa through the pterygo­ maxillary fissure. Pterygomaxillary fissure ⑬ Inferior orbital fissure ⑧ ⑥ ⑪ ⑩ ⑦ Zygomatic process (cut) ⑫ ⑨ ⑤ Pterygoid process, lateral plate Lesser palatine a. ④ ③ ② ① Maxillary a. Greater palatine a. Table 41.8 Branches of the maxillary artery Part Mandibular part (between the origin and the first circle around artery in Fig. 41.29) Pterygoid part (between the first and second circles around the artery) Artery Distribution ① Inferior alveolar a. Mandible, teeth, gingiva ② Anterior tympanic a. Tympanic cavity ③ Deep auricular a. Temporomandibular joint, external auditory canal ④ Middle meningeal a. Calvaria, dura, anterior and middle cranial fossae ⑤ Masseteric a. Masseter m. ⑥ Deep temporal aa. Temporalis m. ⑦ Pterygoid brs. Pterygoid mm. ⑧ Buccal a. Buccal mucosa ⑨ Descending palatine a. Pterygopalatine part (between the second and third circles around the artery) Greater palatine a. Hard palate Lesser palatine a. Soft palate, palatine tonsil, pharyngeal wall ⑩ Posterior superior alveolar a. Maxillary molars, maxillary sinus, gingiva ⑪ Infraorbital a. Maxillary alveoli ⑫ A. of pterygoid canal ⑬ Sphenopalatine a. Lateral posterior nasal aa. Lateral wall of nasal cavity, choanae Posterior septal brs. Nasal septum 601 42 Orbit & Eye Head & Neck Bones of the Orbit Fig. 42.1 Bones of the orbit Frontal incisure Supraorbital foramen Posterior ethmoidal foramen Frontal bone, orbital surface Anterior ethmoidal foramen Zygomaticoorbital foramen Optic canal (sphenoid bone) Nasal bone Superior orbital fissure Maxilla, frontal process Zygomatic bone Inferior orbital fissure Lacrimal bone Ethmoid bone, orbital plate Infraorbital groove A Anterior view. Maxilla, orbital surface Infraorbital foramen Frontal bone, orbital surface Lacrimal bone Maxilla, frontal process Anterior and posterior ethmoidal foramina Lacrimal bone, posterior lacrimal crest Maxilla, anterior lacrimal crest Ethmoid bone Sphenoid, optic canal Superior orbital fissure Fossa of lacrimal sac (with opening for nasolacrimal duct) Foramen rotundum Maxilla, orbital surface Inferior orbital fissure Pterygopalatine fossa B Lateral view of right orbit. Table 42.1 Maxillary hiatus Maxillary sinus Infraorbital foramen Openings in the orbit for neurovascular structures Opening* Nerves Optic canal Optic n. (CN II) Vessels Ophthalmic a. Trigeminal n., ophthalmic division (CN V1) • Lacrimal n. • Frontal n. • Nasociliary n. Superior orbital fissure Oculomotor n. (CN III) Trochlear n. (CN IV) Abducent n. (CN VI) Inferior orbital fissure Infraorbital n. (CN V2) Zygomatic n. (CN V2) Infraorbital canal Infraorbital n. (CN V2), a., and v. Supraorbital foramen Supraorbital n. (lateral br.) Supraorbital a. Frontal incisure Supraorbital n. (medial br.) Supratrochlear a. Anterior ethmoidal foramen Anterior ethmoidal n., a., and v. Posterior ethmoidal foramen Posterior ethmoidal n., a., and v. * The nasolacrimal canal transmits the nasolacrimal duct. 602 Infraorbital canal Superior ophthalmic v. Infraorbital a. and v., inferior ophthalmic v. 42 Orbit & Eye Frontal bone, orbital surface Frontal sinus Superior orbital fissure Zygomatic bone, orbital surface Zygomaticoorbital foramen Table 42.2 Direction Bordering structure Sphenoid bone, lesser wing Superior Sphenoid bone, greater wing Medial Ethmoid sinus Inferior Maxillary sinus Maxilla, orbital surface Frontal sinus Anterior cranial fossa Certain deeper structures also have a clinically important relationship to the orbit: Infraorbital canal Inferior orbital fissure Structures surrounding the orbit Maxillary sinus Sphenoid sinus Hypophysis (pituitary) Middle cranial fossa Cavernous sinus Optic chiasm Pterygopalatine fossa Palatine bone, pyramidal process C Medial view of right orbit. Frontal sinus Ethmoid bone, crista galli Frontal bone, orbital surface Sphenoid bone, lesser wing Ethmoid bone, perpendicular plate Optic canal Ethmoid bone, orbital plate (lamina papyracea) Superior orbital fissure Ethmoid bone, superior nasal concha Sphenoid bone, greater wing Inferior orbital fissure Zygomatic bone, orbital surface Infraorbital canal Orbital floor Ethmoid bone, middle nasal concha Inferior nasal concha Ethmoid bone Maxillary sinus Maxilla, palatine process Vomer DCoronal section, anterior view. 603 Head & Neck Muscles of the Orbit Fig. 42.2 Extraocular muscles The eyeball is moved by six extrinsic muscles: four rectus (superior, inferior, medial, and lateral) and two oblique (superior and inferior). Superior rectus Superior oblique Medial rectus Lateral rectus Inferior oblique (origin) Tendon of superior oblique Inferior rectus Trochlea Superior rectus Inferior oblique Superior oblique Inferior rectus A Right eye, anterior view. Inferior oblique (insertion) Medial rectus Common tendinous ring Lateral rectus Levator palpebrae superioris Optic n. (CN II, in optic canal) B Right eye, superior view of opened orbit. Depress Elevate Fig. 42.3 Testing the extraocular muscles Inferior oblique Lateral rectus Superior oblique Abduct Superior rectus Inferior oblique Medial rectus Inferior rectus Inferior oblique Inferior rectus Superior oblique Lateral rectus Superior oblique Adduct A Starting with the eyes directed anteriorly, movement to any of the cardinal directions of gaze (arrows) requires activation of two extraocular muscles, each of which is innervated by a different cranial nerve, thus testing the function of those pairs of muscles. 604 Superior rectus Abduct Abduct Adduct B Starting with the eyes adducted or abducted, elevating or lowering the eyes activates only the oblique or the rectus muscles, respectively, allowing for testing of the function of individual muscles. 42 Orbit & Eye Fig. 42.4 Actions of the extraocular muscles Superior view of opened orbit. Vertical axis, red circle; horizontal axis, black; anteroposterior (visual/optical) axis, blue. A Superior rectus. Table 42.3 B Medial rectus. C Inferior rectus. DLateral rectus. F Inferior oblique. E Superior oblique. Extraocular muscles Action (see Fig. 42.4)* Muscle Origin Insertion Superior rectus Medial rectus Inferior rectus Common tendinous ring (common annular tendon) Lateral rectus Sclera of the eye Vertical axis (red) Horizontal axis (black) Anteroposterior axis (blue) Innervation Elevates Adducts Rotates medially Oculomotor n. (CN III), superior branch — Adducts — Depresses Adducts Rotates laterally Oculomotor n. (CN III), inferior branch — Abducts — Abducent n. (CN VI) Superior oblique Sphenoid bone+ Depresses Abducts Rotates medially Trochlear n. (CN IV) Inferior oblique Medial orbital margin Elevates Abducts Rotates laterally Oculomotor n. (CN III), inferior branch * Starting from gaze directed anteriorly + The tendon of the superior oblique passes through a tendinous loop (trochlea) attached to the superomedial orbital margin. Clinical box 42.1 Oculomotor palsies Oculomotor palsies may result from a lesion involving an eye muscle or its associated cranial nerve (at the nucleus or along the course of the nerve). If one extraocular muscle is weak or paralyzed, deviation of the eye will be noted. A Abducent nerve palsy. Disabled: Lateral rectus. Impairment of the coordinated actions of the extraocular muscles may cause the visual axis of one eye to deviate from its normal position. The patient will therefore perceive a double image (diplopia). Superior rectus B Trochlear nerve palsy. Disabled: Superior oblique. Lateral rectus 23° Visual (optical) axis Orbital axes C Complete oculomotor palsy. Disabled: Superior, inferior, and medial recti and inferior oblique. DNormal visual and orbital axes. 605 Head & Neck Neurovasculature of the Orbit Superior ophthalmic v. Supratrochlear v. Fig. 42.5 Veins of the orbit Dorsal nasal v. Lateral view of the right orbit. Removed: Lateral orbital wall. Opened: Maxillary sinus. Lacrimal v. Angular v. Cavernous sinus Ophthalmic v. Inferior ophthalmic v. Infraorbital v. Facial v. Clinical box 42.2 Cavernous sinus syndrome Fig. 42.6 Arteries of the orbit Superior view of the right orbit. Opened: Optic canal and orbital roof. Supratrochlear a. Dorsal nasal a. Supraorbital a. Medial palpebral a. Long posterior ciliary aa. Short posterior ciliary aa. Lacrimal a. Anterior ethmoidal a. Central retinal a. Posterior ethmoidal a. Gravity allows venous blood from the danger triangle region of the face (see figure) to drain to the cavernous sinus via the valveless ophthalmic veins. Squeezing a pimple or boil in this facial region can result in infectious thrombi being forced into the venous system and passing back into the cavernous sinus. Cavernous sinus syndrome (CIS) is diagnosed by the loss of eyeball movement due to the various cranial nerves associated with the cavernous sinus becoming infected. The abducent nerve (CN VI) is bathed in blood within the sinus, the first ocular movement to be affected is lateral deviation of the eyeball. The oculomotor (CN III) and trochlear (CN IV) nerves, embedded in the dural lateral wall of the sinus are also eventually affected as the infection penetrates the dura. The eyeball becomes frozen in the orbit as all nerves activating the extraocular mm. become infected. CN V1 is also in the lateral dural wall so a tingling/parasthesia is felt in the sensory region covered (forehead). Occasionally CN V2 may also be involved and this parasthesia may also extend to the skin of the face below the orbit. The intercavernous sinuses allow the infection to spread to the cavernous sinus on the opposite side. If left untreated, death can result however cavernous sinus septic thrombophlebitis mortality has decreased from 100% to 20% with the of improvements in diagnosis and treatment. Optic n. (CN II) Internal carotid a. (in cavernous sinus) Danger triangle Ophthalmic a. 606 Middle meningeal a. (from maxillary a.) Anastomotic br. Fig. 42.7 Innervation of the orbit Frontal n. Lateral view of the right orbit. Removed: Temporal bony wall. Lacrimal n. (with gland) Oculomotor n. (CN III) Supraorbital n. Internal carotid a. with internal carotid plexus Supratrochlear n. Long ciliary nn. Trochlear n. (CN IV) 42 Orbit & Eye Oculomotor n., superior br. Nasociliary n. Ophthalmic division (CN V1) Short ciliary nn. Trigeminal n. (CN V) Ciliary ganglion Trigeminal ganglion Parasympathetic root Mandibular division (CN V3) Abducent n. (CN VI) Maxillary division (CN V2) Optic n. (CN II) Oculomotor n., inferior br. Sympathetic root Nasociliary (sensory) root Fig. 42.8 A course of the cranial nerves through the cavernous sinus toward the orbit Sella turcica with partially opened cavernous sinus on the right side, cranial view. The trigeminal ganglia are displayed on both sides. The right ganglion is pulled laterally from its normal position (thereby exposing the trigeminal cave = Meckel’s cave) to show the cavernous sinus and the internal carotid artery, which passes through the sinus. Note the abducent nerve also traverses the cavernous sinus and runs lateral to the carotid artery. All other nerves (oculomotor, trochlear and the three branches of the trigeminal) run rostrally and caudally in the Optic n. (CN I) lateral dural wall of the cavernous sinus. Most cases of intracavernous carotid aneurysm only involve the abducent nerve. The space-occupying aneurysm compresses the nerve, causing a loss of function. In cases with sudden onset of isolated abducent nerve palsy, carotid aneurysm should always be considered as a possible cause. In contrast, isolated trochlear nerve palsy is rare. More often, the trochlear nerve is one of multiple nerves affected, e.g. in cases of cavernous sinus thrombosis which involves all nerves traveling through the cavernous sinus, often affecting also both branches of the trigeminal nerve. Internal carotid a. Oculomotor n. (CN III) Opthalmic n. (CN V1) Trochlear n. (CN IV) Trochlear n. (CN IV) Trigeminal n. (minor portion) Maxillary n. (CN V2) Oculomotor n. (CN V1) Trigeminal n. (major portion) Mandibular n. (CN V3) Trigeminal ganglion Trigeminal cave Cavernous sinus Trigeminal n. (CN V) Clivus Abducent n. (CN VI) Facial n. (CN VII) 607 Head & Neck Topography of the Orbit Fig. 42.9 Neurovascular structures of the orbit Anterior view. Right side: Orbicularis oculi removed. Left side: Orbital septum partially removed. Medial palpebral lig. Supraorbital a. and n. Superior ophthalmic Infraa. and v. trochlear n. Supratrochlear n. Levator palpebrae superioris Superior tarsal m. Lacrimal gland, orbital part Lacrimal gland, palpebral part Orbital septum Lateral palpebral lig. Superior and inferior tarsus Facial a. and v. Angular a. and v. Dorsal nasal a. and v. Lacrimal sac Infraorbital a. and n. Fig. 42.10 Passage of neurovascular structures through the orbit Anterior view. Removed: Orbital contents. Note: The optic nerve and ophthalmic artery travel in the optic canal. The remaining structures pass through the superior orbital fissure. Lacrimal n. Frontal n. Trochlear n. (CN IV) Levator palpebrae superioris Superior rectus Superior oblique Superior ophthalmic v. Optic n. (CN II, in optic canal) Superior orbital fissure Common tendinous ring Oculomotor n. (CN III), superior br. Ophthalmic a. Nasociliary n. Medial rectus Lateral rectus Inferior orbital fissure Oculomotor n. (CN III), inferior br. Abducent n. (CN VI) 608 Inferior ophthalmic v. Inferior rectus Fig. 42.11 Neurovascular contents of the orbit Superior ophthalmic v. Supraorbital aa. and nn. 42 Orbit & Eye Superior view. Removed: Bony roof of orbit, peritorbita, and retro-orbital fat. Infratrochlear n. Cribriform plate Anterior ethmoidal a. and n. Supratrochlear a. and n. Posterior ethmoidal a. and n. Levator palpebrae superioris Lacrimal a. and n. (with gland) Lateral rectus Supraorbital a. Nasociliary n. Trochlear n. (CN IV) Superior rectus Abducent n. (CN VI) Inferior ophthalmic v. Frontal n. A Upper level. Medial rectus Superior oblique Levator palpebrae superioris Superior rectus Superior ophthalmic v. Lacrimal gland Nasociliary n. Lacrimal a. and n. Long ciliary nn. Trochlear n. (CN IV) Short posterior ciliary aa., short ciliary nn. Optic n. (CN II) Nasociliary n. Lateral rectus Inferior ophthalmic v. Abducent n. (CN VI) Ciliary ganglion Oculomotor n. (CN III) B Middle level. Reflected: Levator palpebrae superioris and superior rectus. Revealed: Optic nerve. 609 Head & Neck Orbit & Eyelid Fig. 42.12 Topography of the orbit Sagittal section through the right orbit, medial view. Episcleral space Orbital roof Bulbar fascia (Tenon’s capsule) Periorbita Levator palpebrae superioris Adipose tissue of the orbit Superior rectus Orbital septum Eyeball Optic n. (with dural sheath) Inferior rectus Orbital septum Inferior oblique Sclera Infraorbital n. Orbital floor Maxillary sinus Fig. 42.13 Eyelids and conjuctiva Sagittal section through the anterior orbital cavity. Orbital roof Periorbita Levator palpebrae superioris Orbital septum Superior rectus Superior conjunctival fornix Orbicularis oculi, orbital part Superior tarsal m. Superior tarsus (with tarsal glands) Lens Upper eyelid Cornea Iris Ciliary body Inferior tarsus Ciliary and sebaceous glands Retina Sclera Lower eyelid Inferior tarsal m. Orbicularis oculi, palpebral part Infraorbital n. 610 Fig. 42.14 Lacrimal apparatus Right eye, anterior view. Removed: Orbital septum (partial). Divided: Levator palpebrae superioris (tendon of insertion). 42 Orbit & Eye Levator palpebrae superioris Orbital septum Lacrimal caruncle Lacrimal gland, orbital part Superior and inferior lacrimal canaliculi Lacrimal gland, palpebral part Medial palpebral lig. Upper eyelid Lacrimal sac Superior and inferior puncta Lower eyelid Nasolacrimal duct Infraorbital foramen Inferior nasal concha Clinical box 42.3 Lacrimal drainage Perimenopausal women are frequently subject to chronically dry eyes (keratoconjunctivitis sicca), due to insufficient tear production by the lacrimal gland. Acute inflammation of the lacrimal gland (due to bacteria) is less common and characterized by intense inflammation and extreme tenderness to palpation. The upper eyelid shows a characteristic S-curve. 611 Head & Neck Eyeball Fig. 42.15 Structure of the eyeball Transverse section through right eyeball, superior view. Note: The orbital axis (running along the optic nerve through the optic disk) ­deviates from the optical axis (running through the center of the eye to the fovea centralis) by 23 degrees. Optical axis Orbital axis Posterior chamber 23° Iris Lens Cornea Anterior chamber Chamber angle Scleral venous sinus (canal of Schlemm) Corneoscleral limbus Pigment epithelium of the ciliary body Ciliary body, ciliary m. Ocular conjunctiva Zonular fibers Ora serrata Hyaloid fossa Vitreous body Medial rectus Lateral rectus Retina Choroid Optic disk Sclera Macula lutea Lamina cribrosa Central retinal a. Fovea centralis Optic n. (CN II) 612 Fig. 42.16 Blood vessels of the eyeball Lesser arterial circle of iris Transverse section through the right eyeball at the level of the optic nerve, superior view. The arteries of the eye arise from the ophthalmic artery, a terminal branch of the internal carotid artery. Blood is drained by four to eight vorticose veins that open into the superior and inferior ophthalmic veins. 42 Orbit & Eye Scleral venous sinus (canal of Schlemm) Anterior conjunctival a. Greater arterial circle of iris Anterior ciliary aa. Arterial circle of Zinn (and von Haller) Short posterior ciliary aa. Pial vascular plexus Long posterior ciliary aa. Vorticose v. Choroid (choroidocapillary layer) Central retinal a. and v. Optic n. (CN II) Clinical box 42.4 Optic fundus The optic fundus is the only place in the body where capillaries can be examined directly. Examination of the optic fundus permits observation of vascular changes that may be caused by high blood pressure or diabetes. Examination of the optic disk is important in determining intracranial pressure and diagnosing multiple sclerosis. Nasal Macula lutea Optic disk Central retinal a. Central retinal v. Temporal Fovea centralis Physiological cup B Normal optic fundus in the ophthalmoscopic examination. Optic disk (blind spot) Central retinal a. and v. (sites of entry and emergence) Macula lutea (yellow spot) A Retina of left eyeball, anterior view, schematic. C High intracranial pressure; the edges of the optic disk appear less sharp. 613 Head & Neck Cornea, Iris & Lens Fig. 42.17 Cornea, iris, and lens Transverse section through the anterior segment of the eye. Anterosuperior view. Anterior chamber Cornea Iris Pupillary sphincter Chamber angle Pupillary dilator Scleral venous sinus (canal of Schlemm) Ocular conjunctiva Ciliary m. Ciliary body Posterior chamber Fig. 42.18 Iris Pupil Cornea Transverse section through the anterior segment of the eye. Anterosuperior view. Lens Zonular fibers Sclera Pupillary sphincter Pupillary dilator Lesser arterial circle of iris Iris stroma Greater arterial circle of iris Pigmented iris epithelium (two layers) Clinical box 42.5 Glaucoma Aqueous humor produced in the posterior chamber passes through the pupil into the anterior chamber. It seeps through the spaces of the trabecular meshwork into the scleral venous sinus (canal of Schlemm) before passing into the episcleral veins. Obstruction of aqueous humor drainage causes an increase in intraocular pressure (glaucoma), which constricts the optic nerve Trabecular meshwork Cornea in the lamina cribrosa. This constriction eventually leads to blindness. The most common glaucoma (approximately 90% of cases) is chronic (openangle) glaucoma. The more rare acute glaucoma is characterized by red eye, strong headache and/or eye pain, nausea, dilated episcleral veins, and edema of the cornea. Anterior chamber Scleral venous sinus (canal of Schlemm) Conjunctiva Episcleral vv. B Chronic (open-angle) glaucoma. Drainage through the trabecular meshwork is impaired. Sclera A Normal drainage. 614 Ciliary body Chamber angle Posterior chamber Iris C Acute (angle-closure) glaucoma. The chamber angle is obstructed by iris tissue. Aqueous fluid cannot drain into the anterior chamber, which pushes portions of the iris upward, blocking the chamber angle. Fig. 42.19 Pupil 42 Orbit & Eye Pupil size is regulated by two intraocular muscles of the iris: the pupillary sphincter, which narrows the pupil (parasympathetic innervation), and the pupillary dilator, which enlarges it (sympathetic innervation). A Normal pupil size. B Maximum constriction (miosis). C Maximum dilation (mydriasis). Fig. 42.20 Lens and ciliary body Posterior view. The curvature of the lens is regulated by the muscle fibers of the annular ciliary body. Lens Iris Ciliary body, pars plicata Ciliary body, pars plana Sclera Choroid Retina, optical part Zonular fibers Ciliary processes Fig. 42.21 Light refraction by the lens Transverse section, superior view. In the normal (emmetropic) eye, light rays are refracted by the lens (and cornea) to a focal point on the retinal surface (fovea centralis). Tensing of the zonular fibers, with ciliary muscle relaxation, flattens the lens in response to parallel rays arriving Ciliary m. from a distant source (far vision). Contraction of the ciliary muscle, with zonular fiber relaxation, causes the lens to assume a more rounded shape (near vision). Nearsightedness (myopia) Retina Fovea centralis Lens Ora serrata Normal vision Farsightedness (hyperopia) Incident light rays Far vision Incident light rays Fovea centralis Near vision Lens A Normal dynamics of the lens. B Abnormal lens dynamics. 615 43 Nasal Cavity & Nose Head & Neck Bones of the Nasal Cavity Fig. 43.1 Skeleton of the nose The skeleton of the nose is composed of an upper bony portion and a lower cartilaginous portion. The proximal portions of the nostrils (alae) are composed of connective tissue with small embedded pieces of cartilage. Major alar cartilage Nasion Lateral crus Nasal bone Medial crus Frontal process of maxilla Lateral nasal cartilage Naris Nasal ala Major alar cartilage Septal cartilage Anterior nasal spine Minor alar cartilages A Left lateral view. B Inferior view. Fig. 43.2 Bones of the nasal cavity The left and right nasal cavities are flanked by lateral walls and separated by the nasal septum. Air enters the nasal cavity through the anterior nasal aperture and travels through three passages: the superior, middle, and inferior meatuses (arrows). These passages are separated by the superior, middle, and inferior conchae. Air leaves the nose through the choanae, entering the nasopharynx. Anterior cranial fossa Cribriform plate Frontal bone Crista galli Sphenoid sinus Frontal sinus Nasal bone Hypophyseal fossa Ethmoid bone, perpendicular plate Sphenoid crest Vomer Septal cartilage Choana Major alar cartilage, medial crus Posterior process Palatine bone, horizontal plate Nasal crest Incisive canal Oral cavity Maxilla, palatine process Left side of nasal septum in left nasal cavity. Parasagittal section. A 616 Anterior Sphenoethmoidal cranial fossa recess Superior meatus Middle cranial fossa Frontal sinus Sphenoid bone, lesser wing Hypophyseal fossa Lacrimal bone Sphenoid sinus Maxilla, frontal process Superior concha (ethmoid bone) Anterior nasal aperture Medial plate Choana Lateral plate 43 Nasal Cavity & Nose Crista galli Pterygoid process Middle meatus Inferior concha Palatine bone, horizontal plate Maxilla, palatine process Inferior meatus Middle concha (ethmoid bone) B Right lateral wall of the right nasal cavity. Sagittal section, medial view. Removed: Nasal septum. Note: The superior and middle conchae are parts of the ethmoid bone, whereas the inferior nasal conchae is a separate bone. Cribriform plate Orifices of posterior ethmoid sinus Superior concha (cut) Sphenoid sinus Sphenopalatine foramen Ethmoid bulla Lacrimal bone Uncinate process Inferior concha (cut) Maxilla, palatine process Middle concha (cut) Maxillary hiatus Palatine bone, perpendicular plate Inferior meatus C Right lateral wall of the right nasal cavity with the conchae removed. Sagittal section, medial view. Revealed: Paranasal sinuses (p. 618). 617 Head & Neck Paranasal Air Sinuses Fig. 43.3 Location of the paranasal sinuses The paranasal sinuses (frontal, ethmoid, maxillary, and sphenoid) are air-filled cavities that reduce the weight of the skull. Age 20 Age 12 Frontal sinus Age 8 Age 1 Age 4 Age 4 Ethmoid sinus Age 1 Age 8 Age 12 Age 20 Maxillary sinus Age 60+ Sphenoid sinus A Anterior view. C Pneumatization (the formation of air-filled cells and cavities) of the sinuses with age. The frontal (yellow) and maxillary (orange) sinuses develop gradually over the course of cranial growth. B Left lateral view. Fig. 43.4 Paranasal sinuses Superior concha Arrows indicate the flow of mucosal secretions from the sinuses and the nasolacrimal duct into the nasal cavity (see Table 43.1). Ethmoid bulla Middle concha (cut) Sphenoethmoidal recess Hiatus semilunaris Frontal sinus Superior meatus Superior concha (cut) Middle meatus Orbit Nasal cavity Ethmoid sinus Middle concha Nasal septum Maxillary sinus Inferior concha (cut) Inferior concha Inferior meatus Openings of the paranasal sinuses and nasolacrimal duct. Sagittal A section, medial view of the right nasal cavity. Table 43.1 Nasal passages into which sinuses empty Sinuses/duct Nasal passage Via Sphenoid sinus (blue) Sphenoethmoidal recess Direct Posterior cells Superior meatus Direct Anterior and middle cells Middle meatus Ethmoid bulla Frontal sinus (yellow) Middle meatus Frontonasal duct into hiatus semilunaris Maxillary sinus (orange) Middle meatus Hiatus semilunaris Nasolacrimal duct (red) Inferior meatus Direct Ethmoid sinus (green) 618 Paranasal sinuses and osteomeatal unit in the left nasal cavity. CoroB nal section, anterior view. Fig. 43.5 Bony structure of the paranasal sinuses Coronal section, anterior view. Ethmoid bone 43 Nasal Cavity & Nose Frontal sinus Anterior cranial fossa Parietal bone Frontal bone Sphenoid bone, lesser wing Temporal bone Ethmoid sinus Sphenoid bone, greater wing Superior orbital fissure (to middle cranial fossa) Zygomatic bone Maxillary sinus Inferior concha Vomer A Bones of the paranasal sinuses. Cribriform plate Crista galli Frontal sinus Perpendicular plate Superior meatus Orbital plate Superior concha Orbit Middle meatus Middle ethmoid sinus Ostium of maxillary sinus Middle concha Uncinate process Maxillary sinus Inferior meatus Inferior concha Vomer Palatine process of maxilla B Ethmoid bone (red) in the paranasal sinuses. Ethmoid sinuses Deviated septum Maxillary sinus Inferior conchae Clinical box 43.1 Deviated septum The normal position of the nasal septum creates two roughly symmetrical nasal cavities. Extreme lateral deviation of the septum may result in obstruction of the nasal passages. This may be corrected by removing portions of the cartilage (septoplasty). Sinusitis C MRI through the paranasal sinuses. When the mucosa in the ethmoid sinuses becomes swollen due to inflammation (sinusitis), it blocks the flow of secretions from the frontal and maxillary sinuses in the osteomeatal unit (see Fig. 43.4). This may cause microorganisms to become trapped, causing secondary inflammations. In patients with chronic sinusitis, the narrow sites can be surgically widened to establish more effective drainage routes. 619 Head & Neck Neurovasculature of the Nasal Cavity Fig. 43.6 Nasal septum and lateral wall Anterior ethmoidal a. Olfactory bulb (CN I) Sphenoid sinus Hypophyseal fossa Frontal sinus Olfactory fibers (CN I) Medial superior posterior nasal brs. (CN V2) Anterior septal brs. (from anterior ethmoidal a.) Posterior septal brs. (from sphenopalatine a.) Medial nasal br. Choana Torus tubarius Pharyngeal orifice of pharyngotympanic (auditory) tube Nasopalatine n. Axis (C2) A Nerves and arteries of the left side of the nasal septum. Sphenoid sinus Cribriform plate Sphenoethmoid recess Superior concha Superior meatus Middle concha Middle meatus Pharyngeal tonsil Inferior concha Salpingopharyngeal fold Limen nasi B Mucosa of the right lateral nasal wall. Sagittal section. Inferior meatus Nasal vestibule Uvula Fig. 43.7 Arteries of the nasal cavity Note: The venous drainage of the nasal cavity is into the a­ nterior facial and ophthalmic veins. Posterior ethmoidal a. Posterior ethmoidal a. Ophthalmic a. Ophthalmic a. Anterior ethmoidal a. Sphenopalatine a. Sphenopalatine a. Descending palatine a. Maxillary a. Anterior septal brs. Internal carotid a. Kiesselbach’s area Posterior septal brs. A Arteries of the left side of the nasal septum. 620 Anterior ethmoidal a. External carotid a. Lateral posterior nasal aa. Greater palatine a. B Arteries of the right lateral nasal wall. Superior concha Sphenoethmoidal recess Fig. 43.8 Lateral nasal wall Sphenoid sinus 43 Nasal Cavity & Nose Frontal sinus Ethmoid bulla Middle concha (cut) Opening of frontonasal duct Inferior concha (cut) Semilunar hiatus Pharyngeal orifice of pharyngotympanic (auditory) tube Opening of nasolacrimal duct Inferior meatus Maxillary n. (V2) Olfactory bulb (CN I) Pterygopalatine ganglion A Lateral nasal wall with middle and inferior conchae removed to show anatomy of underlying meatuses. Trigeminal (CN V) ganglion Internal carotid a. Internal carotid plexus Olfactory fibers, posterior ethmoidal a. Anterior ethmoidal a. Greater petrosal n. Inferior posterior nasal br., lateral posterior nasal aa. Deep petrosal n. N. of the pterygoid canal Clinical box 43.2 Nosebleeds Vascular supply to the nasal cavity arises from both the internal and external carotid arteries. The anterior part of the nasal septum contains a very vascularized region referred to as Kiesselbach’s area. This area is the most common site of significant nosebleeds. Lesser palatine a. and n. Greater palatine n. and a. B Nerves and arteries of the right lateral nasal wall. Sagittal section. Removed: Sphenopalatine foramen. Fig. 43.9 Nerves of the nasal cavity Anterior ethmoidal n. (CN V1) Left lateral view. Olfactory bulb with fibers (CN I) Anterior ethmoidal n. (CN V1) Olfactory fibers (CN I) External nasal br. CN V2 CN V1 Medial nasal brs. Inferior posterior nasal br. CN V3 Nasopalatine n. (CN V2) A Nerves of the left side of the nasal septum. Sphenopalatine foramen Pterygopalatine ganglion (in pterygopalatine fossa) Lateral superior posterior nasal brs. Pterygopalatine ganglion Trigeminal ganglion Medial superior posterior nasal brs. (CN V2) Descending palatine a., greater and lesser palatine nn. Lateral nasal brs. Internal nasal brs. Lesser palatine nn. Greater palatine n. B Nerves of the right lateral nasal wall. 621 Head & Neck Pterygopalatine Fossa The pterygopalatine fossa is a small pyramidal space just inferior to the apex of the orbit. It is continuous with the infratemporal fossa laterally through the pterygomaxillary fissure. The pterygopalatine fossa is a crossroad for neurovascular structures traveling between the middle cranial fossa, orbit, nasal cavity, and oral cavity. Fig. 43.10 Bony boundaries of pterygopalatine fossa Foramen rotundum Sphenoid, greater wing Pterygoid canal Temporal bone, squamous portion Palatovaginal (pharyngeal) canal Maxilla, tuberosity Sphenopalatine foramen Width of pterygomaxillary fissure Maxilla Sphenoid Lateral plate, pterygoid process Palatine A Left lateral view. The lateral approach through the infratemporal fossa via the pterygomaxillary fissure. B Left lateral view. This color-coded version shows the location of the role of palatine bone. Foramen rotundum (from middle cranial fossa) Inferior orbital fissure (to orbit) Sphenopalatine foramen (to nasal cavity) Pterygoid canal (from middle cranial fossa) Greater palatine canal (to oral cavity) Palatovaginal (pharyngeal) canal (from nasopharynx) Pterygopalatine fossa (via pterygomaxillary fissure) Table 43.2 622 Communications of the Pterygopalatine Fossa Communication Direction Via Transmitted structures Middle cranial fossa Posterosuperiorly Foramen rotundum • Maxillary n. (CN V2) Middle cranial fossa Posteriorly in anterior wall of foramen lacerum Pterygoid (vidian) canal • N. of pterygoid canal, formed from: ◦◦ Greater petrosal n. (preganglionic parasympathetic fibers from CN VII) ◦◦ Deep petrosal n. (postganglionic sympathetic fibers from internal carotid plexus) • A. of pterygoid canal • Vv. of pterygoid canal Orbit Anterosuperiorly Inferior orbital fissure • Branches of maxillary n. (CN V2) ◦◦ Infraorbital n. ◦◦ Zygomatic n. • Infraorbital a. and vv. • Communicating vv. between inferior ophthalmic v. and pterygoid plexus of vv. Nasal cavity Medially Sphenopalatine foramen • Nasopalatine (sp) n. (CN V2), lateral and medial superior posterior nasal branches • Sphenopalatine a. and vv. Oral cavity Inferiorly Greater palatine canal (foramen) • Greater (descending) palatine n. (CN V2) and a. • Branches that emerge through lesser palatine canals: ◦◦ Lesser palatine nn. (CN V2) and aa. Nasopharynx Inferoposteriorly Palatovaginal (pharyngeal) canal • Pharyngeal branches of maxillary n. (CN V2), and pharyngeal a. Infratemporal fossa Laterally Pterygomaxillary fissure • Maxillary a., pterygopalatine (third) part • Posterior superior alveolar n., a., and v. tine ganglion synapse with ganglion cells that innervate the lacrimal, small palatal, and small nasal glands. The sympathetic fibers of the deep petrosal nerve (sympathetic root) and sensory fibers of the maxillary nerve (sensory root) pass through the pterygopalatine ganglion without synapsing. The pterygopalatine structures can be seen from the medial view in Fig. 43.8B, p. 621. Fig. 43.11 Nerves in the pterygopalatine fossa Left lateral view. For simplicity in a small, structurally compressed area, numbers are used to identify the nerves. The key to these numbers is found in Table 43.3 (below). ① Fig. 43.12 Coronal view of the pterygopalatine fossa Pterygomaxillary fissure 43 Nasal Cavity & Nose The maxillary division of the trigeminal nerve (CN V2, see Fig. 40.9, p. 567) passes from the middle cranial fossa through the foramen rotun­dum into the pterygopalatine fossa. The parasympathetic pterygopalatine ganglion receives postganglionic fibers from the greater petrosal nerve (the parasympathetic root of the nervus intermedius branch of the facial nerve). The preganglionic fibers of the pterygopala- ④ Maxillary n. (CN V2) Superior orbital fissure ③ ⑧ ② ④ Lacrimal n. ⑤ Posterior superior alveolar n. Ganglionic br. Pterygopalatine ganglion ① Infraorbital n. ⑥ Pharyngeal n. Zygomaticotemporal n. Inferior orbital fissure ② Zygomatic n. Zygomaticofacial n. ⑦ Infraorbital nn. in foramen Posterior superior alveolar n. Descending palatine nn. ⑥, ⑦ Gr./Ls. palatine nn. Dental/gingival br. of superior alveolar nn. Table 43.3 in foramen rotundum Communicating br. between CN V2 and pterygopalatine ganglion ⑤ N. of pterygoid canal entering ganglion from behind Pterygopalatine ganglion ⑧ Posterior superior/ inferior lateral nasal br. of CN V2 Nasopalatine n. Medial/lateral pterygopalatine fossa boundaries Nerves of the pterygopalatine fossa Origin of structures Passageway Transmitted nerves ① Infraorbital n. Orbit Inferior orbital fissure ② Zygomatic n. ③ Orbital brs. (from CN V2) Middle cranial fossa Foramen rotundum ④ Maxillary n. (CN V2) Base of skull Pterygoid (Vidian) canal ⑤N . of pterygoid canal Greater palatine canal ⑥ Greater palatine n. Lesser palatine canals ⑦ Lesser palatine nn. Sphenopalatine foramen ⑧M edial and lateral posterior superior and posterior inferior nasal brs. (from nasopalatine n., CN V2) Palate Nasal cavity 623 44 Temporal Bone & Ear Head & Neck Temporal Bone Fig. 44.1 Temporal bone Left bone. The temporal bone consists of three major parts: squamous, petrous, and tympanic (see Fig. 44.2). Zygomatic process Temporal surface Articular tubercle Mastoid foramen Mandibular fossa A Left lateral view. External acoustic meatus Petrotympanic fissure Styloid process Mastoid process Tympanomastoid fissure Zygomatic process Carotid canal Articular tubercle Mandibular fossa External acoustic meatus Styloid process Mastoid process Jugular fossa Stylomastoid foramen Arterial groove Mastoid notch Mastoid foramen B Inferior view. Zygomatic process Internal acoustic meatus Mastoid foramen C Medial view. 624 Petrous apex Groove for sigmoid sinus Styloid process Fig. 44.2 Parts of the temporal bone Styloid process Tympanic part Petrous part Squamous part 44 Temporal Bone & Ear Squamous part Tympanic part Petrous part A Left lateral view. B Inferior view. Clinical box 44.1 Structures in the temporal bone Internal acoustic meatus The mastoid process contains mastoid air cells that communicate with the middle ear; the middle ear in turn communicates with the nasopharynx via the pharyngotympanic (auditory) tube (A). Bacteria may use this pathway to move from the nasopharynx into the middle ear. In severe cases, bacteria may pass from the mastoid air cells into the cranial cavity, causing meningitis. Temporal bone, petrous part Cochlea Anterior semicircular canal 45° Lateral semicircular canal 90° Chorda tympani Facial n. (CN VII) Facial n. (CN VII), vestibulocochlear n. (CN VIII) B The petrous portion of the temporal bone contains the middle and inner ear as well as the tympanic membrane. The bony semicircular canals are oriented at an approximately 45-degree angle from the coronal, transverse, and sagittal planes (B). Tympanic membrane Pharyngotympanic (auditory) tube Anterior semicircular canal Internal carotid a. Internal jugular v. A Posterior semicircular canal 45° Mastoid air cells Posterior semicircular canal Temporal bone, squamous part Mastoid process Vestibule Cochlea Irrigation of the auditory canal with warm (44°C) or cool (30°C) water can induce a thermal current in the endolymph of the semicircular canal, causing the patient to manifest vestibular nystagmus (jerky eye movements, vestibulo-ocular reflex). This caloric testing is important in the diagnosis of unexplained vertigo. The patient must be oriented so that the semicircular canal of interest lies in the vertical plane (C). Canthomeatal plane 30° Lateral semicircular canal C External acoustic meatus Mastoid process 625 Head & Neck External Ear & Auditory Canal (see p. 634). The inner ear also contains the vestibular apparatus, the organ of balance (see p. 634). The auditory apparatus is divided into three main parts: external, middle, and inner ear. The external and middle ear are part of the sound conduction apparatus, and the inner ear is the actual organ of hearing Fig. 44.3 Ear: Overview Posterior semicircular canal Lateral semicircular canal Coronal section through right ear, anterior view. Anterior semicircular canal Vestibule Vestibular root Cochlear root Vestibulocochlear n. (CN VIII) Cochlea Malleus Temporal bone, petrous part Stapes Tensor tympani Tympanic cavity Incus Pharyngotympanic (auditory) tube Tympanic membrane External auditory canal Clinical box 44.2 Styloid process Curvature of the external auditory canal The external auditory canal is most curved in its cartilaginous portion. When an otoscope is being inserted, the auricle should be pulled backward and upward so the speculum can be introduced into a straightened canal. Fig. 44.4 External auditory canal Coronal section through right ear, anterior view. The tympanic membrane separates the external auditory canal from the tympanic cavity (middle ear). The outer third of the auditory canal is cartilaginous, and the inner two thirds are osseous (tympanic part of temporal bone). Temporal bone, tympanic part A Insertion of otoscope. Tympanic membrane Middle ear Malleus Sebaceous and cerumen glands External auditory canal 626 Incus B Anterior view. Stapes Head of mandible Bony part Cartilaginous part Tympanic membrane C Transverse section. Fig. 44.5 Structure of the auricle Temporoparietal Helicis major Helicis minor Posterior auricular Crura of antihelix Scaphoid fossa Superior auricular (posterior part of temporoparietal) Triangular fossa External auditory canal Antitragus Tragus Cymba conchae External auditory canal Helix 44 Temporal Bone & Ear The auricle of the ear encloses a cartilaginous framework that forms a funnel-shaped receptor for acoustic vibrations. The muscles of the auricle are considered muscles of facial expression, although they are vestigial in humans. B Cartilage and muscles of the right auricle, right lateral view. Tragus Intertragic incisure Antitragus Antihelix Concha Earlobe A Right auricle, right lateral view. Fig. 44.6 Arteries of the auricle Posterior auricular a. Parietal br. Superior auricular Oblique muscle of the auricle Anterior auricular Transverse muscle of the auricle External auditory canal Posterior auricular C Cartilage and muscles of the right auricle, medial view of posterior surface. Frontal br. Perforating brs. Anterior auricular aa. Perforating brs. Posterior auricular Transverse facial a. Anastomotic arcades Superficial temporal a. Maxillary a. A Right auricle, lateral view. Posterior auricular a. External carotid a. Posterior auricular a. B Right auricle, posterior view. External carotid a. Fig. 44.7 Innervation of the auricle Auriculotemporal n. (trigeminal n., CN V) Facial n. (CN VII) A Right auricle, lateral view. Vagus n. (CN X) and glossopharyngeal n. (CN IX) Lesser occipital nn. and great auricular n. (cervical plexus) Facial n. B Right auricle, posterior view. 627 Head & Neck Middle Ear: Tympanic Cavity Pharyngotympanic (auditory) tube Fig. 44.8 Middle ear Right petrous bone, superior view. The tympanic cavity of the middle ear communicates anteriorly with the pharynx via the pharyngotympanic (auditory) tube and posteriorly with the mastoid air cells. Tympanic cavity Internal carotid a. Malleus Incus Cochlea Anterior semicircular canal Facial n. Cochlear n. External auditory canal Vestibular n. Lateral semicircular canal Vestibule Cochlear aqueduct Fig. 44.9 Tympanic cavity and pharyngotympanic tube Endolymphatic sac Medial view of opened tympanic cavity. Cribriform plate Sphenoid sinus Internal carotid a. Hypophysis Mastoid cells Auricle Posterior semicircular canal Pharyngotympanic tube, bony part Sigmoid sinus Tympanic membrane Superior concha Sigmoid sinus Pharyngeal tonsil Internal jugular v. Hard palate Tensor veli palatini Internal carotid a. Cartilaginous part Oral cavity Pharyngeal orifice Membranous lamina Levator veli palatini Uvula Pharyngotympanic (auditory) tube Salpingopharyngeus Boundaries of the tympanic cavity Table 44.1 During chronic suppurative otitis media (inflammation of the middle ear), pathogenic bacteria may spread to adjacent regions. Direction Wall Anatomical boundary Neighboring structures Anterior Carotid Opening to pharyngotympanic tube Carotid canal Lateral Membranous Tympanic membrane External ear Superior Tegmental Tegmen tympani Middle cranial fossa Infection Meningitis, cerebral abscess (especially of temporal lobe) Inner ear Medial Labyrinthine Promontory overlying basal turn of cochlea Inferior Jugular Temporal bone, tympanic part Posterior Mastoid Aditus to mastoid antrum CSF, cerebrospinal fluid. 628 CSF space (via petrous apex) Abducent paralysis, trigeminal nerve irritation, visual disturbances (Gradenigo’s syndrome) Bulb of jugular v. Sigmoid sinus Sinus thrombosis Air cells of mastoid process Mastoiditis Facial n. canal Facial paralysis Epitympanum Fig. 44.10 Tympanic cavity Stapes 44 Temporal Bone & Ear A Levels of the tympanic cavity. Anterior view. The tympanic cavity is divided into three levels: epi-, meso-, and hypotympanum. Tendon of tensor tympani Incus Malleus Mesotympanum External auditory canal Hypotympanum Tympanic membrane Pharyngotympanic (auditory) tube Aditus (inlet) to mastoid antrum Lesser petrosal n. (from tympanic plexus) Facial n. (CN VII) in facial canal Malleus Prominence of lateral semicircular canal Incus Chorda tympani Prominence of facial canal Tensor tympani Stapes Tendon of stapedius Promontory Tympanic membrane Tympanic plexus Tympanic n. (from CN IX) via tympanic canaliculus B Coronal section, anterior view with the anterior wall removed. Anterior semicircular canal Geniculate Roof of tympanic cavity (tegmen tympani) ganglion Vestibular n. (CN VIII) Posterior semicircular canal Facial n. (CN VII) Cochlear n. (CN VIII) Lateral semicircular canal Greater petrosal n. Lesser petrosal n. Oval window Semicanal of tensor tympani Facial n. in facial canal Internal carotid a. Sigmoid sinus, (ghosted) Pharyngotympanic (auditory) tube Promontory Opening for tendon of tensor tympani Internal carotid plexus Mastoid air cells Anterior wall of tympanic cavity Chorda tympani Round window Tympanic plexus Internal jugular v. Tympanic n. entering tympanic canaliculus C Anatomical relationships of the tympanic cavity. Oblique sagittal section showing the medial wall. 629 Head & Neck Middle Ear: Ossicular Chain & Tympanic Membrane Fig. 44.11 Auditory ossicles Left ear. The ossicular chain consists of three small bones that establish an articular connection between the tympanic membrane and the oval window. Incudomalleolar joint Head Body Malleus Incus Stapes Long process Oval window (with anular stapedial lig.) Incudostapedial joint Tympanic membrane Anterior process Malleus Handle Posterior crus Tympanic cavity Anterior crus Stapes Base A Auditory ossicles in the middle ear. Anterior view. B Bones of the ossicular chain. Medial view of the left ossicular chain. Fig. 44.15 Tympanic membrane Fig. 44.12 Malleus (“hammer”) Right tympanic membrane. The tympanic membrane is divided into four quadrantsquadrants (I–IV). Left ear. Head Articular surface for incus Neck Neck Short process Incus Malleolar prominence Neck Lateral process Lateral process Posterior malleolar fold A Posterior view. B Anterior view. Anterior malleolar fold Stapes IV Pars tensa I Umbo Temporal bone, tympanic part Fig. 44.13 Incus (“anvil”) Pars flaccida Incus Handle Anterior process Tympanic incisure Malleolar stria III II Cone of light Left ear. Body Body Articular surface for malleus Short process Short process Long process A Medial view. Lenticular process B Anterolateral view. Left ear. Neck 630 Superior malleolar fold Chorda tympani Malleolar stria Head A Superior view. Incus Stapedius tendon Fig. 44.14 Stapes (“stirrup”) Posterior crus A Lateral view of the right tympanic membranewith quadrants ­indicated. Anterior crus Umbo Base B Medial view. Malleus Lateral lig. of malleus Superior recess of tympanic membrane Malleolar prominence Tympanic membrane B Mucosal lining of the tympanic cavity. Posterolateral view with the tympanic membrane partially removed. Fig. 44.16 Ossicular chain in the tympanic cavity Lateral view of the right ear. Revealed: Ligaments of the ossicular chain and muscles of the middle ear (stapedius and tensor tympani). Superior ligs. of the incus and malleus Incus Incudomalleolar joint Anular stapedial lig. Malleus Tendon of tensor tympani Stapedial membrane 44 Temporal Bone & Ear Posterior lig. of incus Tensor tympani Incudostapedial joint Internal carotid a. Pyramidal eminence Petrotympanic fissure Stapedius Anterior lig. of malleus Stylomastoid a. Chorda tympani Facial n. (CN VII) Posterior tympanic a. Chorda tympani Tympanic membrane Anterior process of malleus Anterior tympanic a. Clinical box 44.3 Ossicular chain in hearing Sound waves funneled into the external auditory canal set the tympanic membrane into vibration. The ossicular chain transmits the vibrations to the oval window, which communicates them to the fluid column of the inner ear. Sound waves in fluid meet with higher impedance; they must therefore be amplified in the middle ear. The difference in surface area between the tympanic Malleus Malleus Incus Axis of movement membrane and the oval window increases the sound pressure 17-fold. A total amplification factor of 22 is achieved through the lever action of the ossicular chain. If the ossicular chain fails to transform the sound pressure between the tympanic membrane and the footplate of the stapes, the patient will experience conductive hearing loss of magnitude 20 dB. Incus Oval window Stapes Stapes A Vibration of the tympanic membrane causes a rocking movement in the ossicular chain. The mechanical advantage of the lever action of the ossicular chain amplifies the sound waves by a factor of 1.3. Pyramidal eminence B The stapes in its normal position lies in the plane of the oval window. Stapedius tendon Anular stapedial lig. Oval window Round window Oval window with anular stapedial lig. Basilar membrane Tympanic membrane DPropagation of sound waves by the ossicular chain. C Rocking of the ossicular chain causes the stapes to tilt. The movement of the stapes base against the membrane of the oval window (stapedial membrane) induces corresponding waves in the fluid column of the inner ear. 631 Head & Neck Arteries of the Middle Ear A Internal carotid a. F D Middle meningeal a. GS H J Maxillary a. Ascending pharyngeal a. Posterior auricular a. Occipital a. External carotid a. Table 44.2 Principal arteries of the middle ear Origin Artery Distribution Internal carotid a. ① Caroticotympanic aa. Tympanic cavity (anterior wall), pharyngotympanic (auditory) tube Ascending pharyngeal a. (medial br.) External carotid a. Maxillary a. (terminal br.) ② Inferior tympanic a. Tympanic cavity (floor), promontory ③ Deep auricular a. Tympanic cavity (floor), tympanic membrane ④ Anterior tympanic a. Tympanic membrane, mastoid antrum, malleus, incus Middle meningeal a. Posterior auricular a. (posterior br.) Stylomastoid a. ⑤ Superior tympanic a. Tympanic cavity (roof), tensor tympani, stapes ⑥ Stylomastoid a. Tympanic cavity (posterior wall), mastoid air cells, stapedius m., stapes ⑦ Posterior tympanic a. Chorda tympani, tympanic membrane, malleus Fig. 44.17 Arteries of the middle ear: Ossicular chain and tympanic membrane Medial view of the right tympanic membrane. With inflammation, the arteries of the tympanic membrane may become so dilated that their course can be observed (as shown here). Tegmen tympani Incus Mastoid antrum Superior tympanic a. Facial n. (CN VII) Tensor tympani Stapedial br., stylomastoid a. Incudostapedial joint (stapes removed) Chorda tympani Anterior tympanic a. Handle of malleus Posterior tympanic a. Pharyngotympanic (auditory) tube Stylomastoid a. Tympanic membrane 632 Deep auricular a. Inferior tympanic a. 44 Temporal Bone & Ear Fig. 44.18 Arteries of the middle ear: Tympanic cavity Right petrous bone, anterior view. Removed: Malleus, incus, portions of chorda tympani, and anterior tympanic artery. Anterior semicircular canal Subarcuate a. Superficial petrosal a., ascending br. Internal auditory a. Facial n. (CN VII) Superficial petrosal a., descending br. Superficial petrosal a. Greater petrosal n. Superior tympanic a. Anterior crural a. Lesser petrosal n. Internal carotid a. Posterior crural a. Stylomastoid a., posterior tympanic br. Stapedial br. Stapedius Promontory Pharyngotympanic (auditory) tube Tubal a. Facial n. (CN VII) Tensor tympani Stylomastoid a. Caroticotympanic aa. Tympanic n. Mastoid a. Stylomastoid a., posterior tympanic br. Deep auricular a. Inferior tympanic a. Clinical box 44.4 Otitis Media Hyperacusis Otitis media is an infection of the middle ear that occurs commonly in children often following an upper respiratory tract infection. Fluid that accumulates in the middle ear can temporarily diminish hearing and inflammation of the lining of the tympanic cavity can block the pharyngotympanic tube. The stapedius muscle protects the delicate inner ear by modifying the vibrations of very loud sounds as they are transmitted through the middle ear to the stapes. Paralysis of the muscle resulting from a lesion of the facial nerve causes an extreme sensitivity to sound, a condition known as hyperacusis. 633 Head & Neck Inner Ear The inner ear consists of the vestibular apparatus (for balance) and the auditory apparatus (for hearing). Both are formed by a membranous labyrinth filled with endolymph floating within a bony labyrinth filled with perilymph and embedded in the petrous part of the temporal bone. Fig. 44.19 Vestibular apparatus Right lateral view. Endolymphatic duct Semicircular canals Anterior ampullary n. Anterior semicircular canal Superior part Anterior semicircular duct Inferior part Lateral ampullary n. Utricle Ductus Saccule reuniens Utricle (with utricular n.) Endolymphatic sac A Schematic. Ampullary crests and maculae of utricle and saccule shown in red. Vestibular ganglion (CN VIII) Lateral semicircular canal Saccule (with saccular n.) Posterior semicircular canal Posterior ampullary n. Endolymphatic duct Ductus reuniens B Structure of the vestibular apparatus. Fig. 44.20 Auditory apparatus The cochlear labyrinth and its bony shell form the cochlea, which contains the sensory epithelium of the auditory apparatus (organ of Corti). Modiolus Scala vestibuli Cochlear duct Scala tympani Oval window Round window Greater petrosal n. Lesser petrosal n. Helicotrema Cochlear canal Cochlear aqueduct Geniculate ganglion Cochlea Tympanic cavity Cochlear n. A Schematic. Facial n. Vestibular n. Chorda tympani Scala vestibuli Cochlear duct Spiral ganglion Temporal bone, petrous part Scala tympani B Compartments of the cochlear canal, cross section. 634 Internal acoustic meatus Semicircular canals C Location of the cochlea. Superior view of the petrous part of the temporal bone with the cochlea sectioned transversely. The bony canal of the cochlea (spiral canal) makes 2.5 turns around its bony axis (modiolus). Fig. 44.21 Innervation of the membranous labyrinth Anterior semicircular duct Anterior ampullary n. divided into the vestibular and cochlear nerves. Note: The sensory organs in the semicircular canals respond to angular acceleration, and the macular organs respond to horizontal and vertical linear acceleration. Vestibular Vestibuloganglion, cochlear n. (CN VIII), superior part vestibular part Vestibular aqueduct Facial n. (CN VII) Vestibular ganglion, inferior part Dura mater Cochlear communicating br. Endolymphatic sac 44 Temporal Bone & Ear Right ear, anterior view. The vestibulocochlear nerve (CN VIII; see p. 570) transmits afferent impulses from the inner ear to the brainstem through the internal acoustic meatus. The vestibulocochlear nerve is Nervus intermedius Lateral ampullary n. Vestibulocochlear n. (CN VIII), cochlear part Common crus Saccular n. Utricular n. Posterior ampullary n. Lateral semicircular duct Modiolus Posterior semicircular duct Spiral ganglion of cochlea Posterior ampulla Oval window Round window Fig. 44.22 Blood vessels of the inner ear Right anterior view. The labyrinth receives its blood supply from the internal auditory artery, a branch of the anteroinferior cerebellar artery (see p. 688). Vestibular a. Vestibular ganglion Vestibular n. (CN VIII) Facial n. (CN VII) V. of vestibular aqueduct Internal auditory a. and vv. Nervus intermedius Cochlear n. (CN VIII) Common cochlear a. Vestibulocochlear a. Cochlear a. proper V. of round window V. of cochlear aqueduct 635 45 Oral Cavity & Pharynx Head & Neck Bones of the Oral Cavity Fig. 45.1 Hard palate The floor of the nasal cavity (the maxilla and palatine bone) forms the roof of the oral cavity, the hard palate. The two horizontal processes of the maxilla (the palatine processes) grow to­ gether during development, eventually fusing at the median palatine suture. Failure to fuse results in a cleft palate. Incisive fossa Palatine process of maxilla Transverse palatine suture Median palatine suture Greater palatine foramen Lesser palatine foramen Inferior orbital fissure Pterygoid process, medial plate Pyramidal process Pterygoid fossa Choana Posterior nasal spine Pterygoid process, lateral plate Foramen for pterygoid plexus A Inferior view. Vomer Pterygoid canal Foramen ovale Anterior nasal spine Maxillary sinus Nasal crest Palatine process of maxilla Transverse palatine suture Perpendicular plate Greater palatine canal Pyramidal process BSuperior view. Removed: Maxilla (upper part). Lateral plate Posterior nasal spine Medial plate Septum of sphenoid sinus Optic canal Sphenoid, lesser wing Superior orbital fissure Ostium of sphenoid sinus Middle concha Pterygoid fossa Ethmoid bone, perpendicular plate Inferior orbital fissure Inferior concha Choana Vomer Median palatine suture 636 Pterygoid process Anterior clinoid process C Oblique posterior view. Palatine bone Incisive foramen Lateral plate Medial plate Palatine bone Palatine process of maxilla Pterygoid process Head (condyle) of mandible Internal oblique ridge Oblique line External oblique ridge The mandible (jaw) is connected to the viscero­ cranium at the temporomandibular joint (p. 638). Coronoid process Ramus of mandible Mental protuberance Head (condyle) of mandible Alveolar process Coronoid process Alveoli (tooth sockets) Mental foramen Mental tubercles Lingula Internal oblique ridge Mandibular foramen Mylohyoid groove Body of mandible A Anterior view. Mandibular notch 45 Oral Cavity & Pharynx Neck of mandible Fig. 45.2 Mandible Pterygoid fovea Head (condyle) of mandible Sublingual fossa Submandib­ ular fossa Pterygoid fovea Coronoid process Condylar process Superior and inferior mental spines (genial tubercles) Mandibular foramen Lingula Digastric fossa Mylohyoid line B Posterior view. Ramus of mandible Alveolar process Mental protuberance Angle Mental tubercle Mental foramen External Body of Oblique oblique ridge mandible line C Oblique left lateral view. Fig. 45.3 Hyoid bone The hyoid bone is suspended in the neck by muscles between the floor of the mouth and the larynx. Although not listed among the cranial Lesser horn Greater horn bones, the hyoid bone gives attachment to the muscles of the oral floor. The greater horn and body of the hyoid are palpable in the neck. Lesser horn Greater horn Lesser horn Body A Anterior view. Greater horn Body B Posterior view. C Oblique left lateral view. 637 Head & Neck Temporomandibular Joint Fig. 45.4 Temporomandibular joint Head of mandible The head of the mandible articulates with the mandibular fossa in the temporomandibular joint. Articular tubercle Mandibular fossa Pterygoid fovea Neck of mandible Coronoid process Articular disk Neck of mandible Lingula Mandibular foramen Head of mandible Mylohyoid groove B Head of mandible, anterior view. CHead of mandible, posterior view. A Sagittally sectioned temporoman­ dibular joint, left lateral view. Zygomatic process, temporal bone Articular tubercle DMandibular fossa of the temporo­ mandibular joint, inferior view. Petrotympanic fissure Mandibular fossa External acoustic meatus (to external auditory canal) Styloid process, temporal bone Mastoid process, temporal bone Fig. 45.5 Ligaments of the temporomandibular joint Pterygoid process, lateral plate Pterygospinous lig. Joint capsule Lateral lig. Spheno­ mandibular lig. Stylomandibular lig. Stylomandibular lig. A Lateral view of the left temporomandibular joint. 638 Pterygoid process, medial plate B Medial view of the right temporomandibular joint. Fig. 45.6 Movement of the temporomandibular joint Clinical box 45.1 Lateral pterygoid, superior head Dislocation of the temporomandibular joint Articular tubercle Mandibular fossa Dislocation may occur if the head of the mandible slides past the articular tubercle. The mandible then becomes locked in a protruded position, a condition reduced by pressing on the mandibular row of teeth. Articular disk Head of mandible Joint capsule 45 Oral Cavity & Pharynx Left lateral view. During the first 15 degrees of mandibular depression (opening of the mouth), the head of the mandible remains in the man­ dibular fossa. Past 15 degrees, the head of the mandible glides forward onto the articular tubercle. Lateral pterygoid, inferior head A Mouth closed. 15° Fig. 45.7 Innervation of the temporo­mandibular joint capsule Superior view. Auriculotemporal n. Mandibular n. (CN V3) Deep temporal n. B Mouth opened to 15 degrees. Masseteric n. Articular tubercle >15° Mandibular fossa Articular disk Joint capsule C Mouth opened past 15 degrees. 639 Teeth Head & Neck Enamel Fig. 45.8 Structure of a tooth Crown Crown Each tooth consists of hard tissue (enamel, dentin, cementum) and soft tissue (dental pulp) arranged into a crown, neck (cervix), and root. Dentin Pulp chamber Neck Neck Gingival margin Alveolar bone Root Root Cementum Apex of root Fig. 45.9 Permanent teeth Incisive fossa Histology of a tooth B (mandibular incisor). A Principal parts of a tooth (molar). Each half of the maxilla and mandible contains a set of three anterior teeth (two incisors, one canine) and five posterior (postcanine) teeth (two premolars, three molars). Incisors Fig. 45.10 Tooth surfaces Interalveolar septum The top of the tooth is known as the occlusal surface. Canine Incisive suture Premolars Labial Mesial Median palatine suture Distal Molars Mesial Transverse palatine suture Palatal Distal Buccal Maxillary teeth. Inferior view of the maxilla. A Distal Buccal Lingual Molars Mesial Premolars Interalveolar septum B Mandibular teeth. Superior view of the mandible. 640 Distal Canine Incisors Mesial Labial Fig. 45.11 Coding of the teeth 1 32 2 3 31 A B C 4 5 6 30 T S 29 28 E D 7 R 27 wise fashion. The third upper right molar is 1; the second upper right premolar is A. F G 9 8 10 Q P O N 26 25 24 23 Fig. 45.12 Dental panoramic tomogram The dental panoramic tomogram (DPT) is a survey radiograph that ­allows preliminary assessment of the temporomandibular joints, maxillary sinuses, maxillomandibular bone, and dental status (carious lesions, M 22 H I 12 13 11 L 21 J K 20 14 15 18 45 Oral Cavity & Pharynx In the United States, the 32 permanent teeth are numbered sequen­ tially (not assigned to quadrants). The 20 deciduous (baby) teeth are coded A to J (upper arch), and K to T (lower arch), in a similar clock­ 16 17 19 location of wisdom teeth, etc.). DPT courtesy of Dr. U. J. Rother, Director of the Department of Diagnostic Radiology, Center for Dentistry and Oromaxillofacial Surgery, ­Eppendorf University Medical Center, Hamburg, Germany. Maxillary sinus Nasal septum Orbit Articular tubercle Mandibular fossa Condylar process 16* 1* 17* 32 Impacted third molar (wisdom tooth) Mandibular angle 31 30 *Not fully erupted. 29 28 27 26 25 Bite guide of scanner Mandibular canal 641 Head & Neck Oral Cavity Muscle Facts Fig. 45.13 Muscles of the oral floor See pp. 516–517 for the infrahyoid muscles. S F 1b G D 1a Styloid process Mastoid process A Suprahyoid muscles, left lateral view. Digastric, posterior belly Hyoglossus Mylohyoid Stylohyoid Digastric, intermediate tendon Digastric, anterior belly Connective tissue sling Infrahyoid muscles Hyoid bone B Left lateral view. F Sublingual fold D 1a Sublingual papilla Oral mucosa G S 1b Genioglossus Mylohyoid raphe Geniohyoid C Suprahyoid muscles, superior view. Mylohyoid Hyoid bone Hyoglossus Stylohyoid DSuperior view of the mandible and hyoid bone. 642 Suprahyoid muscles Table 45.1 Muscle Origin Insertion Anterior belly Mandible (digastric fossa) 1b Posterior belly Temporal bone (mastoid notch, medial to mastoid process) ① Digastric ② Stylohyoid Via an intermediate tendon with a fibrous loop Temporal bone (styloid process) ③ Mylohyoid Via a split tendon Hyoid bone (body) Mandible (mylohyoid line) ④ Geniohyoid Mandible (inferior mental spine) ⑤ Hyoglossus Hyoid bone (superior border of greater cornu) Mylohyoid n. (from CN V3) Facial n. (CN VII) Action Elevates hyoid bone (during swallowing), assists in opening mandible Via median tendon of insertion (mylohyoid raphe) Mylohyoid n. (from CN V3) Tightens and elevates oral floor, draws hyoid bone forward (during swallowing), assists in opening mandible and moving it side to side (mastication) Body of hyoid bone Anterior ramus of C1 via hypoglossal n. (CN XII) Draws hyoid bone forward (during swallowing), assists in opening mandible Hypoglossal n. (CN XII) Depresses and retracts the tongue Sides of tongue Fig. 45.14 Muscles of the soft palate 45 Oral Cavity & Pharynx 1a Innervation Hard palate Inferior view. The soft palate forms the pos­ terior boundary of the oral cavity, separating it from the oropharynx. Inferior orbital fissure Palatine aponeurosis Pterygoid hamulus Lateral pterygoid plate Musculus uvulae Uvula Tensor veli palatini Levator veli palatini Oropharynx (isthmus) Opening of carotid canal Occipital condyles Table 45.2 Muscles of the soft palate Muscle Origin Tensor veli palatini Medial pterygoid plate (scaphoid fossa); sphenoid bone (spine); cartilage of pharyngotympanic tube Levator veli palatini Cartilage of pharyngotympanic tube; temporal bone (petrous part) Musculus uvulae Palatine aponeurosis Innervation Action Medial pterygoid n. (CN V3) Tightens soft palate; opens inlet to pharyngotympanic (auditory) tube (during swallowing, yawning) Raises soft palate to horizontal position Uvula (mucosa) Palatine aponeurosis; posterior nasal spine Tongue (side) Palatine aponeurosis Palatoglossus* Palatopharyngeus* Insertion Vagus n. via pharyngeal plexus Shortens and raises uvula Elevates tongue (posterior portion); pulls soft palate onto tongue Tightens soft palate; during swallowing pulls pharyngeal walls superiorly, anteriorly, and medially *For the palatoglossus, see Figs. 45.19, p. 646 and 45.24, p. 648; and for the palatopharyngeus, see Figs. 45.24, p. 648 and 45.29C, p. 653. 643 Head & Neck Innervation of the Oral Cavity Fig. 45.15 Trigeminal nerve in the oral cavity Right lateral view. Trigeminal n. (CN V) Maxillary division (CN V2, via foramen rotundum) Pterygo­ palatine ganglion Posterior Middle Anterior Superior alveolar nn. Zygomatic n. Infraorbital n. (and foramen) Mandibular division (CN V3, via foramen ovale) Buccal n. Auriculo­ temporal n. Medial pterygoid nn. Masseteric n. Mylohyoid n. Lingual n. Inferior alveolar n. (in mandibular canal) Inferior dental brs. Fig. 45.16 Neurovasculature of the hard palate Mental n. (and foramen) Inferior view. The hard palate receives sensory innervation primarily from terminal branches of the maxillary division of the trigeminal nerve (CN V2). The arteries of the hard palate arise from the maxillary artery. Superior labial brs. Posterior septal brs. Anterior and middle superior alveolar brs. Nasopalatine n. Nasopalatine n. Incisive foramen Median palatine suture Posterior superior alveolar brs. Greater palatine n. Greater palatine n. and a. Greater palatine foramen Buccal n. Lesser palatine foramen Vomer Lesser palatine n. and a. Lesser palatine n. A Sensory innervation. Note: The buccal nerve is a branch of the man­ dibular division (CN V3). 644 Pterygoid process B Nerves and arteries. The muscles of the oral floor have a complex nerve supply with con­ tributions from the trigeminal nerve (CN V3), facial nerve (CN VII), and C1 spinal nerve via the hypoglossal nerve (CN XII). Fig. 45.17 Innervation of the oral floor muscles Mandibular division (CN V3) Inferior alveolar n. Chorda tympani (CN VII) Geniculate ganglion Lingual n. Mylohyoid n. Tympanic plexus Trigeminal ganglion Facial n. (CN VII) Submandibular ganglion Mastoid cells Mandibular division (CN V3) Mylohyoid Digastric, anterior belly Chorda tympani A Mylohyoid nerve (CN V3). Left lateral view with the left half of the mandible removed. Stylomastoid foramen Lingual n. Mastoid process Glossopharyngeal n. (CN IX) Stylohyoid br. (with muscle) Lingual n. 45 Oral Cavity & Pharynx Trigeminal ganglion Digastric br. (with posterior belly) Facial nerve (CN VII). Sagittal section B through the right petrous bone at the level of the mastoid process, medial view. Hypoglossal n. (CN XII) Submandibular ganglion C1 spinal n., anterior ramus Genioglossus Geniohyoid Geniohyoid br. (C1) Inferior root of ansa cervicalis (descendens cervicalis) Superior root of ansa cervicalis (descendens hypoglossus) Anterior rami of the C1 spinal nerve, C left lateral view. Ansa cervicalis 645 Head & Neck Tongue The dorsum of the tongue is covered by a highly specialized mucosa that supports its sensory functions (taste and fine tactile discrimina­ tion). The tongue is endowed with a very powerful muscular body to support its motor properties during mastication, swallowing, and speaking. Palatopharyngeal fold Fig. 45.18 Structure of the tongue Epiglottis Lingual tonsil Superior view. The V-shaped sulcus terminalis divides the tongue into an anterior 2/3rds (oral, presulcal) and a posterior 1/3rd (pharyngeal, postsulcal). Foramen cecum Fig. 45.19 Muscles of the tongue The extrinsic lingual muscles (genioglossus, hyoglossus, palatoglossus, and styloglossus) have bony attachments and move the tongue as a whole. The intrinsic lingual muscles (superior and inferior longitudinal muscles, transverse muscle, and vertical muscle) have no bony attach­ ments and alter the shape of the tongue. Palatine tonsil Palato­ glossal fold Root of tongue Terminal sulcus Dorsum of tongue Dorsum of tongue Palato­ glossus Styloid process Body of tongue Median furrow Apex of tongue Apex of tongue Styloglossus Mandible Hyoglossus Hyoid bone Genio­ glossus Genio­ hyoid Superior view. Taste A Left lateral view. Vagus n. (CN X) Lingual aponeurosis Lingual mucosa Superior longi­ tudinal m. Transverse m. Inferior longi­ tudinal m. Hyoglossus Genioglossus Sublingual gland Mylohyoid B Coronal section, anterior view. 646 Digastric, anterior belly Geniohyoid Somatic sensation Vagus n. (CN X) Glosso­ pharyngeal n. (CN IX) Vertical m. Lingual septum Fig. 45.20 Somatosensory and taste innervation of the tongue Glosso­ pharyngeal n. (CN IX) Facial n. (CN VII, via chorda tympani) Lingual n. (CN V3) Fig. 45.21 Neurovasculature of the tongue Apex of tongue Anterior lingual glands Frenulum Deep lingual a. and v. Sublingual fold Lingual n. Submandibular duct Sublingual papilla Deep lingual a. Lingual n. (CN V3) 45 Oral Cavity & Pharynx The lingual muscles receive somatomotor innervation from the hypoglossal nerve (CN XII), with the exception of the palatoglossus (supplied by the vagus nerve, CN X). Styloid process A Inferior surface of the tongue. Glosso­ pharyngeal n. (CN IX) Submandibular ganglion Hypoglossal n. (CN XII) Lingual a. (from external carotid a.) Lingual v. (to internal jugular v.) Mandible Submental a. and v. Medial pterygoid Sublingual a. Mandibular n. (CN V3) Hyoid bone Otic ganglion B Left lateral view. Styloglossus Sublingual gland Fig. 45.22 Floor of mouth with tongue pulled from midline Right mandible, medial view. The oral cavity is generally dissected on a hemisected head. To see the relationship of structures and the base of the tongue/floor of the mouth, the tongue is pulled out of the plane of the dissection and an incision is made in the mucosa of the region. Submandibular duct Hypoglossal n. (CN XII) Lingual a. Sublingual papilla Submandibular ganglion Lingual n. Submandibular gland, deep part Genioglossus External carotid a. Hypoglossal n. (CN XII) Tongue Mylohyoid 647 Head & Neck Topography of the Oral Cavity & Salivary Glands Fig. 45.23 Divisions of the oral cavity The oral cavity is located below the nasal cavity and anterior to the pharynx. It is bounded by the hard and soft palates, the tongue and muscles of the oral floor, and the uvula. Airway Midsagittal section, left lateral view. Foodway Torus tubarius with lymphatic tissue (tubal tonsils) Pharyngeal tonsil Naso­ pharynx Pharyngeal orifice of pharyngotympanic (auditory) tube Dens of axis (C2) Atlas (C1) Salpingopharyngeal fold Palatine tonsil Right choana Oro­ pharynx Soft palate Laryngo­ pharynx Uvula Palatoglossal fold Organization of A the oral cavity. Lingual tonsil Genioglossus Geniohyoid Epiglottis Hyoid bone Thyrohyoid lig. Divisions of the oral cavity Table 45.3 Part Anterior boundary Posterior boundary Oral vestibule Lips/cheek Dental arches Oral cavity proper Dental arches Palatoglossal arch Fauces (throat) Palatoglossal arch Palatopharyngeal arch Ventricle Vestibular fold Cricoid cartilage Vocal fold Thyroid gland B Boundaries of the oral cavity. Fig. 45.24 Oral cavity topography Right side, anterior view. Soft palate Palatoglossal arch Oral vestibule Pterygomandibular raphe Lingual n. Pterygomandibular fold Palatine tonsil Palatopharyngeal arch Palatoglossus Buccal n. Palatopharyngeus Medial pterygoid Palatine tonsil Uvula Tongue A Open oral cavity. 648 B Oral cavity with mucosa removed from the roof and walls. The three large, paired salivary glands are the parotid, submandibular, and sublingual glands. The parotid gland is a purely serous (watery) salivary gland. The sublingual gland is predominantly mucous; the submandibular gland is a mixed seromucous gland. Parotid gland Parotid duct Fig. 45.25 Salivary glands Superficial temporal a. and v. 45 Oral Cavity & Pharynx Accessory parotid gland Parotid gland, superficial part Parotid plexus Facial n. (CN VII) Buccinator Parotid gland, deep part Masseter Facial a. and v. Submandibular gland, super­ ficial part B Facial nerve in the parotid gland, left lateral view. The branching of the facial nerve into the parotid plexus (see p. 568) separates the parotid gland into a superficial part and a deep part. Sternocleido­ mastoid A Parotid gland, left lateral view. Note: The parotid duct penetrates the buccinator muscle to open opposite the second upper molar. Sternocleido­ mastoid Sublingual papilla Sublingual fold Oral mucosa Genioglossus Sublingual gland Submandibular duct Geniohyoid Mylohyoid Lingual n. Submandib­ ular gland, deep part Inferior alveolar n. Mylohyoid n. Lingual a. C Submandibular and sublingual glands, superior view with tongue removed. Hyoid bone Hyoglossus Submandib­ ular gland, superficial part Stylohyoid 649 Head & Neck Tonsils & Pharynx Fig. 45.26 Tonsils Choana Soft palate Roof of pharynx Palato­ glossal arch Palato­ pharyngeal arch Tonsillar fossa Uvula Palatine tonsil Nasal septum Pharyngeal tonsil Torus tubarius with lymphatic tissue (tubal tonsils) Pharyngeal orifice of pharyngo­ tympanic tube Soft palate Dens of axis (C2) Salpingo­ pharyngeal fold A Palatine tonsils, anterior view. Uvula Pharyngeal tonsil* Nasal conchae Soft palate Roof of pharynx B Pharyngeal tonsils. Sagittal section through the roof of the pharynx. Tubal tonsil* (extension of pharyngeal tonsil) Uvula Lymphatic tissue of lateral bands* along salpingo­ pharyngeal fold Palatine tonsil* Lingual tonsil* Epiglottis Waldeyer’s ring. Posterior view C of the opened pharynx. 650 Table 45.4 Structures in Waldeyer’s ring Tonsil* # Pharyngeal tonsil 1 Tubal tonsils 2 Palatine tonsils 2 Lingual tonsil 1 Lateral bands 2 Clinical box 45.2 Abnormal enlargement of the palatine tonsils due to severe viral or bacterial infection can result in obstruction of the oropharynx, causing difficulty swallowing. Enlarged palatine tonsil Particularly well developed in young children, the pharyngeal tonsil begins to regress at 6 to 7 years of age. Abnormal enlargement is common, with the tonsil bulging into the nasopharynx and obstructing air passages, forcing the child to “mouth breathe.” Choana Enlarged pharyngeal tonsil 45 Oral Cavity & Pharynx Tonsil infections Fig. 45.27 Pharyngeal mucosa Posterior view of the opened pharynx. The anterior portion of the muscular tube contains three openings: choanae (to the nasal cavity), faucial isthmus (to the oral cavity), and aditus (to the laryngeal inlet). Sigmoid sinus Pharyngeal tonsil Middle nasal concha Nasal cavity opening via choana into nasopharynx Nasal septum Inferior nasal concha Stylohyoid Digastric muscle, posterior belly Masseter Soft palate Oral cavity opening via faucial isthmus into oropharynx Uvula Medial pterygoid Palatopharyngeal arch Aryepiglottic fold Laryngeal inlet opening into laryngopharynx Root of tongue (lingual tonsil) Epiglottis Cuneiform tubercle Piriform recess Corniculate tubercle Pharynx (cut) Thyroid gland 651 Head & Neck Pharyngeal Muscles Fig. 45.28 Pharyngeal muscles: Left lateral view Tensor veli palatini Levator veli palatini The pharyngeal musculature consists of the pharyngeal constrictors and the relatively weak pharyngeal elevators. Superior pharyngeal constrictor Stylohyoid Buccinator Styloglossus Digastric muscle, posterior belly Pterygo­ mandibular raphe Stylopharyngeus Hyoglossus Mylohyoid Middle pharyngeal constrictor Digastric muscle, anterior belly Inferior pharyngeal constrictor Sternohyoid (cut) Thyrohyoid Cricothyroid A Pharyngeal muscles in situ. Esophagus S1 S2 S3 Superior pharyngeal constrictor S4 M1 M2 Middle pharyngeal constrictor I1 I2 Inferior pharyngeal constrictor Table 45.5 Pharyngeal constrictors Superior pharyngeal constrictor S1 Pterygopharyngeal part S2 Buccopharyngeal part S3 Mylopharyngeal part S4 Glossopharyngeal part Middle pharyngeal constrictor M1 Chondropharyngeal part M2 Ceratopharyngeal part Inferior pharyngeal constrictor B Subdivisions of the pharyngeal constrictors. 652 I1 Thyropharyngeal part I2 Cricopharyngeal part Fig. 45.29 Pharyngeal muscles: Posterior view 45 Oral Cavity & Pharynx Pharyngobasilar fascia Accessory muscle bundle Superior pharyngeal constrictor Digastric muscle, posterior belly Masseter Stylohyoid Medial pterygoid Stylopharyngeus Middle pharyngeal constrictor Hyoid bone, greater horn Pharyngeal tonsil Inferior pharyngeal constrictor Pharyngeal raphe Pharyngotympanic tube, cartilaginous part Levator veli palatini Salpingo­ pharyngeus Esophagus Tubal orifice Tensor veli palatini Superior pharyngeal constrictor Pterygoid process, medial plate Musculus uvulae Palato­ pharyngeus Pterygoid hamulus B Muscles of the soft palate and pharyngo­ tympanic tube. The muscles of the fauces form the posterior boundary of the oral cavity. Cut on right side: Levator veli palatini and salpingopharyngeus. A Muscles of the posterior pharynx. Tensor veli palatini Levator veli palatini Styloid process Stylohyoid Superior pharyngeal constrictor Digastric, posterior belly Masseter Salpingo­ pharyngeus Pharyngeal elevators Palato­ pharyngeus Stylopharyngeus Oblique arytenoid Musculus uvulae Medial pterygoid Angle of mandible Middle pharyngeal constrictor Transverse arytenoid Posterior cricoarytenoid Muscles in the opened pharynx. C Circular muscle fibers of esophagus 653 Head & Neck Neurovasculature of the Pharynx Fig. 45.30 Neurovasculature in the parapharyngeal space Posterior view. Removed: Vertebral column and posterior structures. Pharyngobasilar fascia Sigmoid sinus CN XI Pharyngeal raphe Occipital a. CN XII Superior pharyngeal constrictor Stylopharyngeus Superior cervical ganglion Middle pharyngeal constrictor CN IX Internal jugular v. Superior laryngeal n. External carotid a. Sternocleido­ mastoid Internal carotid a. Ascending pharyngeal a. CN XII Carotid body Pharyngeal venous plexus Sympathetic trunk Inferior pharyngeal constrictor Superior thyroid a. CN X Common carotid a. Thyroid gland Fig. 45.31 Fasciae and potential tissue spaces in the head Transverse section at the level of the tonsillar fossa, superior view. Fascial boundaries are key to outlining pathways for the spread of infection. Potential spaces in the head, shown on this figure, become true spaces when they are infiltrated by products of infection. These spaces are defined by bones, muscles and fascia and initially confine an infection but eventually allow it to spread through communications between spaces. Buccal space Peritonsillar space Submasseteric space Parapharyngeal space Pterygomandibular space Parotid space Retropharyngeal space 654 Posterior view. Choanae CN VI CN III CN V Middle nasal concha CN VII, CN VIII, nervus intermedius Inferior nasal concha CN IX, X, XI 45 Oral Cavity & Pharynx Fig. 45.32 Neurovasculature of the opened pharynx CN VII CN IX Occipital a. Musculus uvulae Superior cervical ganglion Palatopharyngeus CN XII Salpingopharyngeus CN X CN XI Sternocleidomastoid Superior laryngeal n. Epiglottis CN X Sympathetic trunk Cuneiform tubercle Superior laryngeal a. and internal laryngeal n. Corniculate tubercle Inferior laryngeal v. Oblique part Transverse part Internal jugular v. Arytenoid Posterior cricoarytenoid Common carotid a. Middle cervical ganglion Inferior laryngeal n. (terminal br. of recurrent laryngeal n.) Inferior thyroid a. External jugular v. Left subclavian a. Right recurrent laryngeal n. Stellate ganglion Brachiocephalic trunk CN X, left Left recurrent laryngeal n. CN X, right CN III, oculomotor n.; CN V, trigeminal n.; CN VI, abducent n.; CN VII, facial n.; CN VIII, vestibulocochlear n.; CN IX, glossopharyngeal n.; CN X, vagus n.; CN XI, accessory n.; CN XII, hypoglossal n.. See Chapter 39 for the cranial nerves. 655 46 Sectional & Radiographic Anatomy Head & Neck Sectional Anatomy of the Head & Neck (I) Fig. 46.1 Coronal section through the anterior orbital margin Anterior view. This section shows four regions of the head: the oral cavity, the nasal cavity and sinuses, the orbit, and the anterior cranial fossa. Muscles of the oral floor, the apex of the tongue, the hard palate, the neurovascular structures in the mandibular canal, and the first molar are all seen in the region of the oral cavity. This section reinforces the clinical implications of the relationship of the maxillary sinus with the maxillary teeth and the floor of the orbit and with the maxillary nerve in the infraorbital groove. The medial wall of the orbit shares a thin bony wall (orbital plate) with the ethmoid air cells (sinus). The section is enough anterior so that the lateral bony walls of the orbit are not included due to the lateral curvature of the skull. Anterior cranial fossa Frontal lobe of cerebrum Levator palpebrae superioris Periorbital fat Orbital plate of ethmoid bone Vitreous body Ethmoid sinuses Medial rectus Inferior rectus Middle nasal meatus and concha Inferior oblique Orbicularis oculi Infraorbital n. (from CN V2) in infraorbital groove Maxillary sinus Cartilaginous nasal septum Inferior nasal meatus Inferior nasal concha Vomer Palatine process of the maxilla First upper molar Greater palatine a. Buccinator Oral cavity Tongue Oral vestibule Genioglossus Geniohyoid Mylohyoid Platysma 656 First lower molar Inferior alveolar a., n., and v. in mandibular canal Digastric, anterior belly Fig. 46.2 Coronal section through the orbital apex Superior sagittal sinus Falx cerebri Frontal lobe of cerebrum 46 Sectional & Radiographic Anatomy Anterior view. In this more posterior section than that of Fig. 46.1, the soft palate now separates the oral and nasal cavities. The buccal fat pad is also visible. The section is slightly angled, producing an apparent discontinuity in the mandibular ramus on the left side. Olfactory n. (CN I) Superior oblique Superior rectus Lateral rectus Temporalis Optic n. (CN II) Ethmoid sinuses Medial rectus Inferior rectus Nasal septum Infraorbital n. (from CN V2) Zygomatic arch Masseter Maxillary sinus Nasal cavity Coronoid process Soft palate Mandibular ramus Buccal fat pad Medial pterygoid Buccinator Tongue Body of mandible Genioglossus Lingual n., deep lingual a. and v. Mylohyoid Inferior alveolar n., a., and v. in mandibular canal Hyoglossus Digastric, anterior belly Geniohyoid 657 Head & Neck Sectional Anatomy of the Head & Neck (II) Fig. 46.3 Coronal section through the pituitary Anterior view. Superior sagittal sinus Falx cerebri Lateral ventricle Corpus callosum Parietal lobe Caudate nucleus, head Internal capsule Putamen Temporalis Anterior cerebral a. Optic n. (CN II) Oculomotor n. (CN III) Internal carotid a. Trochlear n. (CN IV) Temporal lobe Abducent n. (CN VI) Hypophysis in hypophyseal fossa Cavernous sinus Sphenoid sinus Zygomatic process, temporal bone Septum of sphenoid sinus Ophthalmic n. (CN V1) Maxillary n. (CN V2) Middle cranial fossa Mandibular n. (CN V3) Masseter Lateral pterygoid Nasopharynx Lingual n. Lingual n. Inferior alveolar n. Inferior alveolar n. Mandible, ramus Medial pterygoid Uvula Oropharynx Epiglottis Laryngopharynx 658 Palatine tonsil Fig. 46.4 Midsagittal section through the nasal septum Left lateral view. 46 Sectional & Radiographic Anatomy Corpus callosum Frontal sinus Anterior cranial fossa Olfactory bulb (CN I) Hypophysis Sphenoid sinus Clivus Transverse sinus Choana Foramen magnum Nasal septum Atlas (C1), anterior and posterior arches Hard palate, maxilla (palatine process) Nuchal lig. Soft palate Transverse lig. of atlas Nasopharynx Median atlantoaxial joint Uvula Axis (C2), dens Mandible C3 vertebra Oropharynx Geniohyoid Mylohyoid Vallecula Hyoid bone Laryngeal cartilage Epiglottis Laryngopharynx 659 Head & Neck Sectional Anatomy of the Head & Neck (III) Fig. 46.5 Sagittal section through the medial orbital wall Left lateral view. This section passes through the inferior and middle conchae of the lateral nasal wall. Three of the four paranasal air sinuses (ethmoid, sphenoid, and frontal) are seen in this section and in relation to the nasal cavity into which they drain. In the region of the cervical Caudate nucleus, head Internal capsule spine, the vertebral artery is cut at multiple levels. The spinal nerves have been cut just prior to their lateral exit through the intervertebral foramina. Medial segment of globus pallidus Uncus Lateral ventricle Posterior thalamic nuclei Oculomotor n. (CN III) Optic n. (CN II) Pontocerebellar cistern Frontal sinus Tentorium cerebelli Ethmoid sinus Cerebellum Pharyngotympanic (auditory) tube Sphenoid sinus Middle nasal concha Vertebral a. Inferior nasal concha Rectus capitis posterior minor Palatine process, palatine sulcus Semispinalis capitis Maxilla Rectus capitis posterior major Superior labial vestibule C2 spinal n. Oral cavity Palatopharyngeus Obliquus capitis inferior Inferior labial vestibule Longus capitis Tongue Splenius capitis Mandible Lingual n. and deep lingual vv. C3 spinal n. Spinalis cervicis Digastric, anterior belly C4 spinal n. Mylohyoid Hyoid bone Epiglottic cartilage and vallecula 660 Laryngopharynx Thyroid cartilage Vertebral a. C5 spinal n. C6 spinal n. C7 spinal n. Left lateral view. This section passes through the maxillary, frontal, and sphenoid sinuses and a single ethmoidal air cell. The pharyngeal and masticatory muscles are revealed grouped around the cartilaginous Extreme capsule External capsule Claustrum part of the pharnygotympanic (auditory) tube. The palatine tonsil of the oral cavity and medial portion of the submandibular gland below the floor of the mouth are also seen in this section. Putamen Internal capsule Dentate gyrus Amygdala Trigeminal ganglion (CN V) 46 Sectional & Radiographic Anatomy Fig. 46.6 Sagittal section through the inner third of the orbit Internal carotid a. Lateral rectus Superior rectus Pharyngotympanic (auditory) tube Frontal sinus Posterior meningeal a. Optic n. (CN II) Procerus CN IX, X, and XI in jugular foramen Inferior rectus Vitreous body CN V2 in pterygopalatine fossa Hypoglossal n. (CN XII) Transverse sinus Ethmoid sinus Sphenoid sinus Lateral pterygoid Condylar emissary v. Rectus capitis posterior major Levator veli palatini Medial pterygoid Semispinalis capitis Internal carotid a. Maxillary sinus Obliquus capitis inferior Palatine tonsil Orbicularis oris Greater occipital n. (C2) Palatopharyngeus Vertebral a. C3 spinal n. Tongue Trapezius Genioglossus Mylohyoid Splenius capitis Digastric, anterior belly Retropharyngeal space Hyoid bone, lesser cornu Submandibular gland Hyoid bone, greater cornu Thyroid cartilage, left lamina Inferior pharyngeal constrictor 661 Head & Neck Sectional Anatomy of the Head & Neck (IV) Fig. 46.7 Transverse section through the optic nerve and pituitary Inferior view. Nasal cavity Lens Vitreous body Lacrimal gland Optic n. (CN II) Nasal septum Ethmoid sinuses Medial rectus Lateral rectus Optic canal Internal carotid a. Temporalis Hypophysis Oculomotor n. (CN III) Cavernous sinus Pons Cerebellum, vermis Dorsum sellae Basilar a. Interpeduncular fossa Tentorium cerebelli Inferior sagittal sinus Lateral ventricle, occipital horn Falx cerebri Superior sagittal sinus 662 Superior view. This section passes through the soft palate and mucoperiosteum of the hard palate. The articulation of the odontoid process (dens of C2) with the axis (C1) at the median atlantoaxial joint is shown, as well as the carotid sheath, containing the vertical neuro- Soft palate (including tensor and levator veli palatini) Maxilla vascular elements of the neck. The vertebral artery is sectioned as it prepares to enter the foramen magnum and fuse with its opposite to form the basilar artery. Mucoperiosteum of hard palate Lateral pterygoid plate Levator anguli oris 46 Sectional & Radiographic Anatomy Fig. 46.8 Transverse section of head through the median atlantoaxial joint Buccinator Masseter Lingual n. Medial pterygoid Inferior alveolar n. Lateral pterygoid Atlas (C1) Mandibular ramus Glossopharyngeal n. (CN IX) Maxillary a. Internal carotid a. Internal jugular v. Accessory n. (CN XI) Facial n. (CN VII) in parotid gland Hypoglossal n. (CN XII) Vagus n. (CN X) Occipital a. Median atlantoaxial joint Posterior condylar emissary v. Splenius capitis Dens of axis (C2) Vertebral a. Transverse lig. of atlas Occipital bone Spinal Trapezius cord Semispinalis capitis 663 Head & Neck Sectional Anatomy of the Head & Neck (V) Fig. 46.9 Transverse section of the neck Transverse section at the level of the C5 vertebral body. Inferior view. The internal and external jugular veins are separated by the sternocleidomastoid. The accessory nerve (CN XI) is just medial to this muscle as Arytenoid cartilage it prepares to innervate it from behind. The elongated spinous process of the C7 vertebra (vertebra prominens) is also visible in the section due to the lordotic curvature of the neck. Epiglottic cartilage Laryngeal vestibule Platysma Omohyoid Piriform recess Thyrohyoid Superior thyroid v. Thyroid cartilage Common carotid a., internal jugular v., and vagus n. (CN X) in carotid sheath Sternocleidomastoid Oropharynx C5 vertebra External jugular v. Longus colli Accessory n. (CN XI), external branch C4 spinal n. Vertebral a. C5 spinal n. C6 vertebral body C6 spinal n. Longissimus capitis Levator scapulae Longissimus cervicis Trapezius Splenius cervicis Splenius capitis 664 Spinous process of C 7 Semispinalis cervicis Arytenoid cartilage Inferior view. Thyroid cartilage Sternohyoid Thyrohyoid Superior thyroid v. Laryngopharynx Omohyoid Common carotid a., internal jugular v., and vagus n. (CN X) in carotid sheath Thyroid gland Sternocleidomastoid Longus colli Anterior scalene with C5 spinal n. C4 spinal n. Vertebral v. Middle scalene C6 spinal n. and C6 vertebra Vertebral a. Posterior scalene C7 spinal n. and C7 vertebra Levator scapulae T1, vertebral arch Trapezius Semispinalis cervicis Fig. 46.11 Transverse section of the neck Transverse section at the level of the C7/T1 vertebral junction. Inferior view. This section reveals the roots of spinal nerves C6 to C8 of the brachial plexus passing between the anterior and middle scalene muscles. The phrenic nerve is on the anterior surface of the anterior scalene and Superior thyroid v. Cricoid cartilage Superior thyroid a. Internal jugular v., vagus n. (CN X), and common carotid a. Phrenic n. with anterior scalene External jugular v. 46 Sectional & Radiographic Anatomy Fig. 46.10 Transverse section at the level of the C6 vertebral body Splenius cervicis the components of the carotid sheath (internal jugular vein, common carotid artery, and vagus nerve) lie in the interval between this muscle, the sternocleidomastoid, and the thyroid gland. Sternohyoid Sternothyroid Thyroid gland Sternocleidomastoid Esophagus Thyrocervical trunk Inferior thyroid a. C6 spinal n. Vertebral a. and v. C7 spinal n. Middle scalene C8 spinal n. Intervertebral disk T1 vertebra and spinal n. Posterior scalene Second rib Transverse process of T2 665 Head & Neck Radiographic Anatomy of the Head & Neck (I) Fig. 46.12 Radiograph of the skull Anteroposterior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Frontal sinus Roof of orbit Ethmoidal air cells Nasal septum and inferior nasal concha Maxillary sinus Maxilla Angle, mandible Mental protuberance Fig. 46.13 Coronal MRI through the eyeball Ethmoid sinus Mandible Superior sagittal sinus Falx cerebri with superior frontal gyrus Anterior view. Roof of orbit Levator palpebrae superioris, superior rectus, and supraorbital n. Superior oblique with superior ophthalmic v. Lacrimal gland Eyeball Lateral rectus Medial rectus with ophthalmic a. Inferior rectus and inferior oblique Periorbital fat Zygomatic bone Infraorbital a., v., and n. Middle and inferior nasal conchae Maxillary sinus Nasal septum Maxilla, alveolar process Buccinator Tongue Mandibular tooth 666 Genioglossus Lingual n., deep lingual a. and v. Fig. 46.14 Radiograph of the skull Coronal suture Dorsum sellae Frontal sinus Hypophyseal fossa (sella turcica) Anterior clinoid process Sphenoid sinus Ethmoidal sinus Clivus Maxillary sinus Hard palate 46 Sectional & Radiographic Anatomy Left lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Oral cavity Manidble Fig. 46.15 Midsagittal MRI through the nasal septum Left lateral view. Boxed area represents the location of the ventricular system, thalamus, and pons. A more detail labeled version of this area can be seen in Fig. 51.5, p. 700. (Reproduced from Moeller TB, Reif E. Hypophysis Pocket Atlas of Sectional Anatomy, Vol 1, 4th ed. New York, NY: Thieme; 2014.) Optic n. (CN II) Septum pellucidum Superior sagittal sinus Ethmoid sinus and sphenoid sinus Corpus callosum Straight sinus Fourth ventricle Confluence of the sinuses Frontal sinus Nasal bone Basilar a. Nasopharynx Rectus capitis posterior minor Nuchal lig. Hard palate Dens of axis (C2) and anterior arch of atlas (C1) Tongue C2/C3 intervertebral disk Mandible, body Uvula Oropharynx Semispinalis capitis 667 Head & Neck Radiographic Anatomy of the Head & Neck (II) Fig. 46.16 Radiograph of the skull Inferosuperior oblique view (Waters view). (Reproduced Frontal sinus from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. Nasal bone New York, NY: Thieme; 2010.) Orbit Nasal septum Infraorbital foramen Maxillary sinus Sphenoid sinus Sphenoid sinus, median septum Oropharynx Tongue Mandible Fig. 46.17 Radiograph of the mandible Left lateral view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Radiographic Anatomy, 3rd ed. New York, NY: Thieme; 2010.) Temporomandibular joint (TMJ) Mandible, condyle Coronoid process, mandible Mandibular notch Mandible Mandibular foramen Mental protuberance Mandibular canal Mental foramen Apical foramen of tooth Mandible, angle 668 Fig. 46.18 Transverse MRI through the orbit and nasolacrimal duct Orbicularis oris Middle nasal concha Nasal septum Nasal bone Maxilla with infraorbital canal Levator labii superioris Nasolacrimal duct Maxillary sinus Temporalis Medial pterygoid between medial and lateral pterygoid plates Masseter Lateral pterygoid Pharyngeal recess Mandibular condyle Levator and tensor veli palatini 46 Sectional & Radiographic Anatomy Inferior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 1, 4th ed. New York, NY: Thieme; 2014.) Mandibular and auriculotemporal nn. (from CN V3) Internal carotid a. Internal jugular v. with CN IX, X, and XI Longus capitis Mastoid air cells Vertebral a. Sigmoid sinus Medulla oblongata Cerebellum, posterior lobe Falx cerebri around superior sagittal sinus Occipital bone Fourth ventricle Fig. 46.19 Transverse MRI through the neck Inferior view. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 1, 4th ed. New York, NY: Thieme; 2014.) Thyroid cartilage Sternohyoid and thyrohyoid Anterior jugular vv. Platysma Sternothyroid Larynx Thyroid gland Internal jugular v. Cricoid cartilage Common carotid a. Sternocleidomastoid with external jugular v. Scalene mm. Esophagus Levator scapulae Vertebral a. and v. Spinalis cervicis Semispinalis cervicis C7 spinal n. root Splenius capitis C6 vertebral body, C7 posterior arch C7 spinous process Multifidus Trapezius 669 Head & Neck Radiographic Anatomy of the Head & Neck (III) Fig. 46.20 CT scan of temporomandibular joint (TMJ) Coronal section. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Anatomy: The Musculoskeletal System. New York, NY: Thieme; 2009.) Temporalis Temporal lobe Temporal bone Articular disk Zygomatic process Inferior synovial cavity Lateral joint capsule Internal carotid a., petrous part Mandible, head Mandible, ramus Medial pterygoid Masseter Fig. 46.21 CT scan of temporomandibular joint (TMJ) Sagittal section, mouth closed. (Reproduced from Moeller TB, Reif E. Atlas of Sectional Superior synovial Anatomy: The Musculocavity skeletal System. New York, Articular disk NY: Thieme; 2009.) Articular tubercle Temporalis Cerebrum, temporal lobe Inferior synovial cavity Retrodiskal region Mandible, head Lateral pterygoid, superior head Lateral pterygoid, inferior head External acoustic meatus Mandible, neck Mandible, ramus Inferior alveolar n. in mandibular canal 670 Cranial view. In this angiogram note that the right posterior cerebral a. arises from the internal carotid artery instead of the basilar artery—a variant. The normal configuration is seen on the left side. (Reproduced from Moeller TB, Reif E. Pocket Atlas of Sectional Anatomy, Vol 1, 4th ed. New York, NY: Thieme; 2014.) Anteromedial frontal br. of anterior cerebral a. Ophthalmic a. Anterior communicating a. Internal carotid a. Anterior cerebral a. Left posterior communicating a. Middle cerebral a. Right posterior cerebral a. 46 Sectional & Radiographic Anatomy Fig. 46.22 Cranial MR angiography Superior cerebellar a. Left posterior cerebral a. Basilar a. Temporal a. Parieto-occipital a. Fig. 46.23 Dural venous sinus system of the head Right lateral view. Lateral internal carotid arteriogram, venous phase. Bridging vv. Superior sagittal sinus Internal cerebral v. Inferior sagittal sinus Great cerebral v. (of Galen) Confluence of sinuses Transverse sinus Superior petrosal sinus Sigmoid sinus Cavernous sinus Inferior petrosal sinus Occipital sinus Internal jugular v. 671 Brain & Nervous System 47 Brain Nervous System: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . Nervous System: Development . . . . . . . . . . . . . . . . . . . . . . . Brain, Macroscopic Organization . . . . . . . . . . . . . . . . . . . . . . Diencephalon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brainstem & Cerebellum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ventricles & CSF Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 674 676 678 680 682 684 48 Blood Vessels of the Brain Veins & Venous Sinuses of the Brain . . . . . . . . . . . . . . . . . . . 686 Arteries of the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 688 49 Functional Systems Anatomy & Organization of the Spinal Cord. . . . . . . . . . . . . . 690 Sensory & Motor Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . 692 50 Autonomic Nervous System Autonomic Nervous System (I): Overview . . . . . . . . . . . . . . . 694 Autonomic Nervous System (II) . . . . . . . . . . . . . . . . . . . . . . . 696 51 Sectional & Radiographic Anatomy Sectional Anatomy of the Nervous System . . . . . . . . . . . . . . 698 Radiographic Anatomy of the Nervous System . . . . . . . . . . . 700 47 Brain Brain & Nervous System Nervous System: Overview CNS both white and gray matter Brain Spinal cord Telencephalon (cerebral hemispheres) Segments (only functionally, not morphologically displayable) Diencephalon Cerebellum A Brainstem Midbrain (mesencephalon) C Pons Medulla oblongata B Fig. 47.1 Morphology of the Central Nervous System (CNS) A and B Right side of the brain, medial view; C Section of the spinal cord, ventral view. A general morphological overview of the entire nervous system is necessary to help with understanding the material that follows. The CNS is divided into the brain and the spinal cord with the brain subdivided into the following regions: • Cerebral hemispheres (telencephalon or endbrain) • Interbrain (diencephalon) • Cerebellum • Brain stem composed of the midbrain (mesencephalon), pons (bridge) and medulla oblongata In contrast, the other part of the CNS, the spinal cord appears morphologically rather as one homogenous structure. In terms of its functions, however, the spinal cord can also be divided into segments. The division of gray and white matter is clearly visible: • Gray matter: centrally located, butterfly-shaped structure • White matter: substance that surrounds the “butterfly” Fig. 47.2 Axes of the nervous system and directional terms The same planes, axes and directional terms apply for both the entire body and the PNS. However, with the CNS, one differentiates between two axes: Parietal/ dorsal superior Cranial/oral Frontal/cranial/ oral/rostral anterior ② Note: In order to avoid topographical misunderstandings, the following directional terms for axis No. 2 (Forel axis) are used: Basal/ ventral inferior Ventral ① Caudal 674 Occipital/ caudal posterior • Axis No. 1: Meynert axis: It corresponds to the axes of the body and is used to designate locations in the spinal cord, brainstem (truncus encephali) and cerebellum. • Axis No. 2: Forel axis. It turns horizontally through the diencephalon and telencephalon and forms an 80° angle to axis 1. As a result, the diencephalon and telencephalon lie “face down”. Dorsal • basal instead of ventral • parietal instead of dorsal • frontal and oral/rostral respectively instead of cranial • occipital instead of caudal Gray matter White matter 47 Brain PNS ② Ganglia ① Spinal ganglion (dorsal root ganglion) Nerves Spinal nerves A ① anterior root ② posterior root Cranial nerves Ganglion of cranial nerve “False cranial nerves” (cranial nerves I and II) B “True cranial nerves” (cranial nerves III-XII) Splanchnic nerves (can be functionally and topographically further divised, see pp. 280–281) Autonomic ganglia (these ganglia can be functionally and topographically further divised, see pp. 280–281) C Fig. 47.3 Morphology of the peripheral nervous system A Segment of the spinal cord, ventral view; B Base of the brain; C view of sympathetic ganglia and nerves located anterior to the sacrum. The nerves and ganglia forming the peripheral nervous system are generally named for the part of the CNS with which they communicate: • Spinal nerves (connect the periphery of the body with the spinal cord. Usually 31 or 32 pairs. Spinal nerves (except those related to vertebral levels T1 to T11 or T12) generally have their anterior rami form plexuses for reasons of functionality. • Cranial nerves (connect the periphery of the body to the brain). 12 pairs. Nerve cells found within ganglia (in the PNS) can be classified based on their affiliation with a particular functional division of the nervous system: • Sensory neurons can be found within either division of the nervous system. In the PNS, sensory neurons are found within the sensory (dorsal root) ganglia on the posterior (dorsal) root of the spinal nerve. In the CNS, sensory neurons are found within the sensory nuclei associated with the appropriate cranial nerves that contain sensory fibers. • Ganglia of the autonomic nervous system contain postganglionic sympathetic and parasympathetic neurons that control the organs of the body. Autonomic ganglia are associated with splanchnic nerves that take vasomotor fibers to the viscera. The autonomic nervous system also demonstrates characteristic plexus formation. Note: The distinction of sensory nerves in the CNS applies except for a few special cases. For instance, cranial nerves I (olfactory) and II (optic) are not true nerves but parts of the telencephalon or diencephalon, which clearly makes them part of the CNS. For historical reasons, they have been called “nerves”, which is systematically false. These “bogus” cranial nerves (colored red on the brain in the figure above) are often contrasted with the 10 true cranial nerves (colored yellow on this figure), which are clearly part of the PNS. In the interest of clarity, further details are located within each region throughout the atlas. 675 Brain & Nervous System Nervous System: Development Fig. 47.4 Central and peripheral nervous systems The CNS consists of the brain and spinal cord, which constitute a functional unit. The PNS consists of the nerves emerging from the brain and spinal cord (cranial and spinal nerves, respectively). Nerves emerging from the spinal canal after the end of the spinal cord, form the cauda equina (see p. 41) Cranial nn. Brain Fig. 47.5 Gray and white matter in the CNS Nerve cell bodies appear gray in gross inspection, whereas nerve cell processes (axons) and their insulating myelin sheaths appear white. Spinal nn. White matter Cerebral cortex Spinal cord Gray matter Basal ganglia A Coronal section through the brain. Cauda equina Gray matter White matter B Transverse section through the spinal cord. Table 47.1 Neural tube Development of the brain Primary vesicle Region Structure Prosencephalon (forebrain) Telencephalon (cerebrum) Cerebral cortex, white matter, and basal ganglia Diencephalon Epithalamus (pineal), dorsal thalamus, subthalamus, and hypothalamus Mesencephalon (midbrain)* Rhombencephalon (hindbrain) Metencephalon Myelencephalon Tectum, tegmentum, and cerebral peduncles Cerebellum Pons* Medulla oblongata* Cerebellar cortex, nuclei, and peduncles Nuclei and fiber tracts * The mesencephalon, pons, and medulla oblongata are collectively known as the brainstem. 676 Fig. 47.6 Embryonic development of the brain Left lateral view. 47 Brain Cervical flexure Medulla oblongata Cranial flexure Insula Pons Pons Optic cup Medulla oblongata A Start of 2nd month. C3rd month of development. Telodiencephalic sulcus Insula Hypophysis primordium Eye Mammillary tubercle Olfactory bulb Pons Medulla oblongata D7th month. B End of 2nd month. Fig. 47.7 Adult brain See Fig. 47.10 for lobes of the cerebrum. CN, cranial nerve. Frontal lobe Central sulcus Precentral gyrus Postcentral gyrus Longitudinal cerebral fissure Parietal lobe Optic chiasm Frontal lobe Optic n. (CN II) Hypophysis Occipital lobe Lateral sulcus Temporal lobe Temporal lobe Pons Pons Cerebellum Medulla oblongata Medulla oblongata Left lateral view. A Cerebellum Cingulate gyrus Cervical spinal cord B Basal view. Pineal gland Corpus callosum Mesencephalon Thalamus Occipital lobe Hypothalamus Hypophysis C Right hemisphere, midsagittal section. Pons Medulla oblongata Cerebellum 677 Brain & Nervous System Brain, Macroscopic Organization Fig. 47.8 Cerebrum surface anatomy of the cerebrum can be divided macroscopically into 4 lobes: frontal, parietal, temporal, and occipital. The surface contours of the cerebrum are defined by convolutions (gyri) and depressions (sulci). Left lateral view. The cerebrum is part of the anterior subdivision of the embryonic forebrain (telencephalon)—the part of the adult forebrain that includes the cerebral hemispheres and associated structures. The Superior frontal gyrus Precentral gyrus Central sulcus Postcentral gyrus Middle frontal gyrus Superior parietal lobule Intraparietal sulcus Superior frontal sulcus Inferior frontal sulcus Inferior frontal gyrus Supramarginal gyrus Opercular part Triangular part Orbital part Parietooccipital sulcus Frontal pole Occipital pole Anterior ramus Lateral sulcus (of Sylvius) Ascending ramus Posterior ramus Temporal pole Superior temporal gyrus Inferior Inferior temporal temporal sulcus gyrus Superior temporal sulcus Preoccipital Transverse occipital notch sulcus Middle temporal gyri Parietal operculum Fig. 47.9 Insular lobe Lateral view of the retracted left cerebral hemisphere. Part of the cerebral cortex sinks below the surface during development forming the insula (or insular lobe). Those portions of the cerebral cortex that overlie this deeper cortical region are called opercula (“little lids”). Frontal operculum Insular lobe (= insula) 678 Inferior parietal lobule Angular gyrus Temporal operculum Calcarine sulcus Fig. 47.10 Lobes in the cerebral hemispheres The isocortex also may be functionally divided into association areas (lobes). Parietal lobe Temporal lobe 47 Brain Insula Central sulcus Frontal lobe Occipital lobe Insular lobe (insula) B Lateral view of the retracted left cerebral hemisphere. Limbic lobe (limbus) Frontal pole A Left hemisphere, lateral view. Lateral sulcus Cingulate gyrus Olfactory n. (CN I) Corpus callosum Parietooccipital sulcus Optic n. (CN II) Hypophysis Mammillary body Septum pellucidum Mesencephalon Fornix DBasal view with the brainstem removed. C Right hemisphere, medial view. Occipital pole Longitudinal cerebral fissure Fig. 47.11 Midsagittal section of the brain showing the medial surface of the right hemisphere The brain has been split along the longitudinal cerebral fissure. Medial frontal gyrus Cingulate sulcus Paracentral Paracentral lobule Central sulcus sulcus Marginal sulcus Cingulate gyrus Corpus callosum Sulcus of corpus callosum Precuneus Choroid plexus Parieto-occipital sulcus Interventricular foramen Cuneus Calcarine sulcus Subcallosal gyrus Third ventricle Interthalamic adhesion Septum pellucidum 679 Brain & Nervous System Diencephalon The diencephalon is the posterior subdivision of the forebrain—the part of the adult forebrain that includes the thalamus and associated structures. Fig. 47.12 Diencephalon Right hemisphere, midsagittal section, medial view. The major components of the diencephalon are the thalamus, hypothalamus, and hypophysis (anterior lobe). The diencephalon is located below the corpus callosum, part of the cerebrum, and above the midbrain. The thalamus makes up four-fifths of the diencephalon but the only parts that can be seen externally are the hypothalamus (seen on the basal aspect of the brain) and portions of the epithalamus. In the adult brain the diencephalon is involved in endocrine functioning and autonomic coordination of the pineal, neurohypophysis, and hypothalamus. It also acts as a relay station for sensory information and somatic motor control via the thalamus. Hypothalamic sulcus (ventral diencephalic sulcus) Thalamus Corpus callosum Choroid plexus Fornix Interthalamic adhesion Stria medullaris thalami Pineal (epiphysis) Anterior commissure Preoptic area Hypothalamus Supraoptic recess Infundibular recess Cerebellum Infundibulum Anterior lobe (adenohypophysis) Tuber Posterior lobe (neurohypophysis) cinereum Hypophysis 3rd ventricle Mammillary body Cerebral Tegmentum Cerebral Quadrigeminal aqueduct plate peduncle Mesencephalon Fig. 47.13 Arrangement of the diencephalon around the third ventricle Oblique transverse section through the telecephalon with the corpus callosum, fornix, and choroid plexus removed, posterior view. This figure clearly illustrates that the lateral wall of the third ventricle forms the medial boundary of the diencephalon. 680 v. Fig. 47.14 The diencephalon and brainstem Corpus callosum Lateral geniculate body 47 Brain Left lateral view. The cerebral hemispheres have been removed from around the thalamus. The cerebellum has also been removed. The parts of the diencephalon visible in this dissection are the thalamus, the lateral geniculate body, and the optic tract. The latter two are components of the visual pathway. This dissection illustrates the role the diencephalon plays in linking the underlying brainstem to the overlying cerebral hemispheres. Thalamus Pulvinar Pineal Optic tract Superior colliculus Optic nerve Inferior colliculus Infundibulum Quadrigeminal plate Mammillary body Cerebral peduncle Brachium of inferior colliculus Cerebellum Fig. 47.15 Location of the diencephalon in the adult brain Basal view of the brain (brainstem has been sectioned at the level of the pons). The structures that can be identified in this view represent those parts of the diencephalon situated on the basal surface of the brain. This view also demonstrates how the optic tract winds around the cerebral peduncles. The expansion of the telencephalon during development limits the number of structures of the diencephalon visible on the under­surface of the brain. They are: • Optic nerve • Optic chiasm • Optic tract • Tuber cinerum with the infundibulum • Mammilary bodies • Lateral geniculate body • Neurohypophysis Optic nerve Optic chiasm Infundibulum Tuber cinereum Hypothalamus Mammillary body Optic tract Cerebral peduncle Substantia nigra Red nucleus Lateral geniculate body Cerebral aqueduct 681 Brain & Nervous System Brainstem & Cerebellum he stalk-like region of the brain connecting the cerebral hemispheres T to the cerebellum and spinal cord consists of the diencephalon (thalamus and associated structures) and the brainstem—composed of the mesencephalon or midbrain, pons and medulla oblongata moving sequentially caudal. Fiber bundles pass through this region from the spinal cord on their way to and from the cerebrum; thick fiber bundles pass contralaterally from the cerebrum into the cerebellar hemispheres; and 10 of the 12 cranial nerves are associated with the brainstem. Corpus callosum Fig. 47.16 Diencephalon, brainstem, and cerebellum Choroid plexus Left lateral view. Pineal Tectal Lateral geniculate body Thalamus Pulvinar Anterior lobe Hypothalamus Optic chiasm Primary fissure Infundibulum Mammillary body Infundibulum Horizontal fissure Posterior lobe Cerebral peduncle Pons Horizontal fissure Adenohypophysis Neurohypophysis Superior medullary velum Posterolateral fissure Tonsil Flocculus Medulla oblongata Pyramid A Isolated structures. Fig. 47.17 Cerebellum Anterior lobe Central lobule Primary fissure Lingula Anterior commissure Quadrigeminal plate Optic n. (CN II) Primary fissure Culmen Choroid plexus Nodule B Midsagittal section. Tracts of afferent (sensory) or efferent (motor) axons enter or leave the cerebellum through cerebellar peduncles. Afferent axons originate in the spinal cord, vestibular organs, inferior olive, and pons. Efferent axons originate in the cerebellar nuclei. Lateral parts Vermis Superior cerebellar peduncle Folium of vermis Inferior semilunar lobule Superior medullary Central lobule velum Superior cerebellar peduncle Middle cerebellar peduncle Horizontal fissure Anterior spinocerebellar tract Middle cerebellar peduncle Trigeminal n. (CN V) Vestibulocochlear n. (CN VIII) Facial n. (CN VII) Lingula 4th ventricle Inferior cerebellar peduncle Central tegmental tract Olive Nodule Flocculus Horizontal fissure Uvula vermis Flocculonodular lobe Intermediate parts Pyramid Vallecula of vermis B Anterior view. 4th ventricle Fig. 47.18 Cerebellar peduncles Quadrangular lobule Simple lobule Posterior lobe A Superior view. Prebiventral fissure Median part Superior semilunar lobule 682 Fornix Tonsil Peduncle of flocculus Inferior cerebellar peduncle Fig. 47.19 Brainstem Oculomotor n. (CN III) Interpeduncular fossa Cerebral peduncle 47 Brain The brainstem is the site of emergence and entry of the 10 pairs of true cranial nerves (CN III–XII). See pp. 560–561 for an overview of the cranial nerves and their nuclei. Pons Diencephalon Trigeminal n. (CN V) Cerebral aqueduct Mesencephalon Cerebellum Hypophysis Pons 4th ventricle Rhomboid fossa Medulla oblongata Abducent n. (CN VI) Facial n. (CN VII) Nervus intermedius Vestibulocochlear n. (CN VIII) Olive Glossopharyngeal n. (CN IX) A Levels of the brainstem. Pyramid of medulla oblongata Vagus n. (CN X) Hypoglossal n. (CN XII) Cerebral peduncle Brachium of inferior colliculus Accessory n. (CN XI) Superior colliculus Inferior colliculus Pons CN V, motor root Anterior median fissure C1 spinal n., anterior root Decussation of pyramids Tectal plate B Anterior view. Trochlear n. (CN IV) Superior cerebellar peduncle CN V, sensory root Middle cerebellar peduncle Inferior cerebellar peduncle CN VIII CN VII Lateral aperture CN VI CN X Nervus intermedius CN IX CN XI CN XII C Left lateral view. Brachium of superior colliculus Anterolateral sulcus Posterolateral sulcus Brachium of inferior colliculus Superior and inferior colliculi Superior medullary velum Superior cerebellar peduncle CN IV CN V Medial eminence Middle cerebellar peduncle Inferior cerebellar peduncle Rhomboid fossa Vestibular area Olive C1 spinal n., ventral root Pineal Facial colliculus Striae medullaris CN XII, trigone Taenia cinerea CN X, trigone Tubercle of nucleus cuneatus Tubercle of nucleus gracilis DPosterior view. 683 Brain & Nervous System Ventricles & CSF Spaces Fig. 47.20 Circulation of cerebrospinal fluid (CSF) The brain and spinal cord are suspended in CSF. Produced continually in the choroid plexus, CSF occupies the subarachnoid space and ventricles of the brain and drains through arachnoid granulations into the dural Arachnoid granulations venous sinus system (primarily the superior sagittal sinus) of the cranial cavity. Smaller amounts drain along proximal portions of the spinal nerves into venous plexuses or lymphatic pathways. Choroid plexus (lateral ventricle) Choroid plexus (3rd ventricle) Superior sagittal sinus Ambient cistern Interhemispheric cistern Straight sinus Interventricular foramen Cerebral aqueduct Confluence of sinuses Cistern of lamina terminalis Basal cistern Vermian cistern Choroid plexus (4th ventricle) Chiasmatic cistern Cerebellomedullary cistern (cisterna magna) Interpeduncular cistern Pontomedullary cistern Median aperture Central canal of the spinal cord Spinal cord Vertebral venous plexus CSF flow Subarachnoid space Ventricle Vein or venous sinus Choroid plexus 684 Subarachnoid space Endoneural space Spinal n. Fig. 47.21 Ventricular system 3rd ventricle 47 Brain The ventricular system is a continuation of the central spinal canal into the brain. Cast specimens are used to demonstrate the connections between the four ventricular cavities. Lateral ventricle, left Anterior horn Right lateral ventricle Inferior horn Cerebral aqueduct Left lateral ventricle Collateral trigone Lateral recess Posterior horn B Lateral ventricles in transverse section. 4th ventricle Anterior horn A Superior view. Collateral trigone Lateral ventricle Posterior horn Interventricular foramen Inferior horn 3rd ventricle 4th ventricle Cerebral aqueduct Lateral ventricle Lateral recess C Left lateral ventricle in parasagittal section. Central canal DLeft lateral view. Fig. 47.22 Ventricular system in situ Left lateral view. Lateral ventricle Interthalamic Fornix (central part) adhesion Interventricular foramen Suprapineal recess Pineal recess Pineal gland 3rd ventricle Cerebral aqueduct Corpus callosum Anterior Interventricular Septum foramen pellucidum commissure Fornix Corpus callosum Lateral ventricle (anterior horn) Collateral trigone Supraoptic recess Optic chiasm Lateral ventricle (posterior horn) Infundibular recess Hypophysis Quadrigeminal plate Hypothalamus Infundibulum Cerebral peduncle (crus cerebri) Pons Medulla oblongata A 3rd and 4th ventricles in midsagittal section. Lateral ventricle (inferior horn) 4th ventricle Lateral recess, ends as a lateral aperture of 4th ventricle Central canal Median aperture of 4th ventricle B Ventricular system with neighboring structures. 685 48 Blood Vessels of the Brain Brain & Nervous System Veins & Venous Sinuses of the Brain Additional information on the venous sinus system and dural folds of the cranial cavity can be found on pp. 590–593. Fig. 48.1 Superficial cerebral veins Bridging vv. Superior anastomotic v. Superior sagittal sinus Superior cerebral vv. Inferior anastomotic v. Medial and lateral superior cerebellar vv. Superficial middle cerebral v. Confluence of sinuses Superior and inferior petrosal sinuses Transverse sinus Occipital sinus Petrosal v. Sigmoid sinus Internal jugular v. A Left hemisphere, lateral view. Superior sagittal sinus Thalamostriate v. Superior cerebral vv. Inferior sagittal sinus Anterior v. of septum pellucidum Internal occipital v. Great cerebral v. Straight sinus Anterior cerebral v. Confluence of sinuses Internal cerebral v. Transverse sinus Basilar v. Superior cerebellar v. 686 Occipital sinus Posteromedian medullary v. B Right hemisphere, medial view. Fig. 48.2 Basal cerebral venous system Basal (inferior) view. Anterior communicating v. Anterior cerebral v. Peduncular v. Deep middle cerebral v. Inferior choroidal v. 48 Blood Vessels of the Brain Superficial middle cerebral v. Basilar v. Internal cerebral v. Posterior venous confluence Great cerebral v. Fig. 48.3 Veins of the brainstem Basal (inferior) view. Basilar v. Interpeduncular v. Pontomesencephalic v. Trigeminal n. (CN V) Superior petrosal v. Superior cerebellar vv. Transverse pontine vv. Anterolateral and anteromedian pontine v. Transverse medullary vv. Posteromedian medullary v. 687 Brain & Nervous System Arteries of the Brain Fig. 48.4 Internal carotid artery Left lateral view. See p. 582 for details of the internal carotid artery. Posterior communicating a. Posterior cerebral a. Cerebral part Fig. 48.5 Arteries of the brainstem and cerebellum Petrous part Left lateral view. Internal carotid a. Posterior cerebral a. Basilar a. Superior cerebellar a. Cervical part CN III External carotid a. Common carotid a. Vertebral a. Labyrinthine a. Aortic arch Left subclavian a. Fig. 48.6 Arteries of the brain CN V Basilar a. Anteroinferior cerebellar a. CN VI Vertebral a. Posteroinferior cerebellar a. Basal (inferior) view. Postcommunicating part (A2) Anterior cerebral a. Internal carotid a. Precommunicating part (A1) Postcommunicating part (P2) Posterior cerebral a. Precommunicating part (P1) Lateral occipital a. (P3) Anterior inferior cerebellar a. Posterior inferior cerebellar a. Vertebral a. 688 Anterior communicating a. Sphenoidal part (M1) Insular part (M2) Middle cerebral a. Posterior communicating a. Anterior choroidal a. Pontine aa. Superior cerebellar a. Basilar a. Medial occipital a. (P4) Anterior spinal a. Fig. 48.7 Cerebral arteries A. of central sulcus A. of postcentral sulcus Fig. 48.8 Cerebral arteries: Distribution areas Posterior parietal a. The central gray and white matter have a complex blood supply (yellow) that includes the anterior choroidal artery. Temporooccipital br. Corpus Lateral callosum ventricle Thalamus Prefrontal a. Lateral frontobasal a. Anterior, middle, and posterior temporal brs. Caudate nucleus Insula Cortical margin 48 Blood Vessels of the Brain A. of precentral sulcus A Middle cerebral artery. Left hemisphere, lateral view. Aa. of precentral, central, and postcentral sulci Claustrum Internal capsule Hippocampus Globus pallidus Posterior parietal a., angular gyral br. Middle cerebral a. Anterior cerebral a. Middle cerebral a. Posterior cerebral a. Left hemisphere, lateral view. A Temporooccipital br. Lateral frontobasal a. Cortical margin Anterior, middle, and posterior temporal brs. Corpus callosum Septum pellucidum B Middle cerebral artery. Left lateral view with the lateral sulcus retracted. Pericallosal a. Cingular br. Putamen Precuneal brs. Parietooccipital brs. Callosomarginal a. Anterior commissure Dorsal callosal br. Polar frontal a. Optic chiasm 3rd ventricle Lateral Thalamus ventricle Cerebral aqueduct Pineal (epiphysis) B Right hemisphere, medial view. Parietooccipital br. Anterior cerebral a. Posterior cerebral a. Anterior temporal a. (P3) Middle and posterior temporal brs. Medial occipital a. (P4) C Anterior and posterior cerebral arteries. Right hemisphere, medial view. 689 49 Functional Systems Brain & Nervous System Anatomy & Organization of the Spinal Cord Fig. 49.1 Anatomy of a spinal cord segment Three dimensional representation, oblique anterior view from upper left. The gray matter of the spinal cord is found internally, surrounding the central canal in an H-shaped, or butterfly-like, configuration. This is the reverse of what was seen in the brain where the gray matter was Gray commissure on the external aspect in a cortical configuration. The primary function of the spinal cord is to conduct impulses to and from the brain. To facilitate this, both gray and white matter are organized into longitudinal groupings. Posterior column Posterior median sulcus Posterior intermediate sulcus Posterior gray horn Central canal Posterior rootlets Lateral column Sensory ganglion Posterior root Spinal nerve Intermediolateral gray horn Anterior root Anterior gray horn Anterior rootlets Anterior medial fissure Anterior column Anterolateral sulcus Fig. 49.3 Innervation of muscles Fig. 49.2 Organization of the gray matter Left oblique anterosuperior view. The gray matter of the spinal cord is divided into three columns (horns). • Anterior column (horn): contains motor neurons • Lateral column (horn): contains sympathetic or parasympathetic (visceromotor) neurons in selected regions • Posterior column (horn): contains sensory neurons Motor neurons that innervate specific muscles are arranged into vertical columns in the anterior horn of gray matter, the columns themselves can be called nuclei, in a fashion similar to that seen in brainstem motor nuclei. Most muscles (intersegmental muscles) receive innervation from numerous motor nuclei spanning several spinal cord segments. Monosegmental (or indicator) muscles have their motor neurons located entirely within a single spinal cord segment. Nuclear column Sensory (blue) and motor (red) neurons within these columns are clustered in nuclei according to function. Anterior root Posterior horn (sensory) Peripheral n. Plexus Lateral horn (visceromotor) Sensory nuclei Anterior horn (motor) Motor nuclei Columns 690 Nuclei Spinal cord segment Monosegmental muscle innervation Multisegmental muscle innervation Fig. 49.4 Organization of the white matter Posterior funiculus Ascending tracts (sensory) Lateral funiculus Interneuron Upper motor neuron (in the motor cortex) Neuron in the sensory cortex Tertiary sensory neuron Secondary sensory neuron Anterior funiculus 49 Functional Systems Left oblique anterosuperior view. The gray matter columns partition the white matter analogously into anterior, lateral, and posterior columns or funiculi. The white matter of the spinal cord contains ascending and descending tracts which are the CNS equivalent of peripheral nerves. Descending tracts (motor) Funiculi Tracts Fig. 49.5 Overview of sensorimotor integration Schematic illustrates the pathway of incoming primary sensory neuron impulses, the axon of which ascends to synapse with the secondary and tertiary sensory neurons in the brainstem and cerebrum ending in a synapse on a neuron in the sensory cortex. An interneuron links this with an upper motor neuron in the motor cortex which then descends through the white matter funiculi of the spinal cord to a motor neuron, which then synapses with a lower motor neuron, the axon of which passes out the spinal nerve to the effector organ. Fig. 49.6 Principle intrinsic fascicles of the spinal cord (shaded yellow) Left oblique anterosuperior view. The majority of muscles have a multi­ segmental mode of innervaton that necessitates axons to ascend/descend multiple spinal cord segments to coordinate spinal reflexes. The neurons of these axons originate from interneurons in the gray matter forming intrinsic reflex pathways of the spinal cord. These axons are collected into intrinsic fascicles which are arranged chiefly around the gray matter. These bundles make up the intrinsic circuits of the spinal cord. Interfascicular fasciculus (only in cervical cord) Longitudinal fasciculus of posterior column Lateral fasciculus proprius Sulcomarginal fasciculus Septomarginal fasciculus (only in thoracic cord) Philippe-Gombault triangle (only in sacral cord) Motor interneuron Lower motor neuron Primary sensory neuron Fig. 49.7 Intrinsic circuits of the spinal cord Sensory neurons are shown in blue, motor neurons in red. The neurons of the spinal reflex circuits are in black. These chains of interneurons, which are entirely contained within the spinal cord, comprise the intrinsic circuits of the cord. The axons of these intrinsic circuits pass to adjacent segments in intrinsic fascicles located along the edge of the gray matter. Spinal ganglion α-motor neuron Intercalated cell Projection neuron Commissural cell Association cell α-motor neuron 691 Brain & Nervous System Sensory & Motor Pathways Fig. 49.8 Sensory pathways (ascending tracts) Sensory cortex (postcentral gyrus) 3rd neurons Thalamus Accessory nucleus cuneatus Nucleus cuneatus 2nd neuron ② Cuneocerebellar fibers Nucleus gracilis Medial lemniscus ④ Anterolateral system (spinothalamic tracts) ② ③ ① Unconscious proprioception Position sense, conscious proprioception, vibration, touch * ⑤ Pressure, touch Pain, temperature H G Sensory ganglion of spinal n. (with 1st neurons) 2nd neurons F D S α-motor neuron *The fasciculi cuneatus and gracilis convey information from the upper and lower limbs, respectively. At this spinal cord level, only the fasciculus cuneatus is present. A Table 49.1 Sensory pathways (ascending tracts) of the spinal cord Tract Function Neurons ① Anterior spinothalamic tract Anterior funiculus Pathway for crude touch and pressure sensation ② Lateral spinothalamic tract Anterior and lateral funiculi Pathway for pain, temperature, tickle, itch, and sexual sensation 1st afferent neurons located in spinal ganglia; contain 2nd neurons and cross in the anterior commissure ③ Anterior spinocerebellar tract ④ Posterior spinocerebellar tract Lateral funiculus Pathway for unconscious coordination of motor activities (unconscious proprioception, automatic processes, e.g., jogging, riding a bike) to the cerebellum Projection (2nd) neurons receive proprioceptive signals from 1st afferent fibers originating at the 1st neurons of spinal ganglia ⑤ Fasciculus cuneatus Posterior funiculus Pathway for position sense (conscious proprioception) and fine cutaneous sensation (touch, vibration, fine pressure sense, two-point discrimination) ⑥ 692 Location Fasciculus gracilis Conveys information from upper limb (not present below T3) Conveys information from lower limb Cell bodies of 1st neuron located in spinal ganglion; pass uncrossed to the dorsal column nuclei Descending tracts from brainstem (extrapyramidal motor system) Precentral gyrus (primary motor cortex) Leg Arm Postcentral gyrus (primary somatosensory cortex) Face Fig. 49.9 Motor pathways (descending tracts) Supplementary motor cortex, premotor cortex Tegmental nucleus Corticospinal tracts Corticospinal fibers Corticonuclear fibers 49 Functional Systems Corticospinal tracts (pyramidal tract) Red nucleus Substantia nigra From cerebellum Pyramidal tract Ventral intermedius nucleus CN VII Inferior olive CN XII Pyramid Spinal n., posterior root Pyramidal decussation ② ③ ⑦ ② Spinal n., anterior root ① Table 49.2 ① Function ① Descending tracts from the brainstem (Extrapyramidal motor system) ⑥ ④ Descending tracts of the spinal cord Tract Corticospinal tract (pyramidal tract) α-motor ⑤ neuron (with interneurons) Anterior corticospinal tract ② Lateral corticospinal tract ③ Rubrospinal tract ④ Reticulospinal tract ⑤ Vestibulospinal tract ⑥ Tectospinal tract ⑦ Olivospinal tract Most important pathway for voluntary motor function Originates in the motor cortex Corticonuclear fibers to motor nuclei of cranial nerves Corticospinal fibers to motor cells in anterior horn of the spinal cord Corticoreticular fibers to nuclei of the reticular formation S D F Pathway for automatic and learned motor processes (e.g., walking, running, cycling) A H G 693 50 Autonomic Nervous System Brain & Nervous System Autonomic Nervous System (I): Overview Fig. 50.1 Autonomic nervous system Except in the head, parasympathetic preganglionic neurons synapse in ganglia in the wall of the target organ. Short postganglioinc parasympathetic neurons then innervate the organ. In the head there are four parasympathetic ganglia: ciliary, pterygopalatine, submandibular, and otic, which are associated with cranial nerves III, VII, and IX, respectively. These four ganglia are responsible for distributing fibers to smooth muscle within the eye and to the salivary glands and glands of the nasal cavity, paranasal sinuses, hard and soft palate, and pharynx. Both sympathetic and parasympathetic preganglionic neurons secrete acetylcholine, which acts upon nicotinic receptors in the ganglia. Sympathetic postganglionic neurons secrete norepinephrine, which acts upon adrenoceptors (α or β) in target tissues. Parasympathetic postganglionic neurons secrete acetylcholine, which acts upon muscarinic receptors in target tissues. The autonomic nervous system is the part of the peripheral nervous system that innervates smooth muscle, cardiac muscle, and glands. It is subdivided into the sympathetic (red) and the parasympathetic (blue) nervous systems, which often act in antagonistic fashion to regulate blood flow, secretions, and organ function. Both the sympathetic and parasympathetic nervous systems have a two-neuron pathway, which is under central nervous system control via an upper motor neuron with its cell body in the hypothalamus. In the sympathetic system, the preganglionic neuron synapses within the ganglia of the sympathetic trunk (paired, one on each side of vertebral column) or on one of the unpaired prevertebral ganglia located at the base of the artery for which the ganglion was named (celiac, superior and inferior mesenteric). Sympathetic postganglionic neurons then either reenter spinal nerves via gray rami communicans and are distributed to their target structure or they reach their target structure by travelling with arteries. Parasympathetic ganglia (in the head) Sympathetic nervous system Eye Superior cervical ganglion Parasympathetic nervous system CN VII CN III Lacrimal and salivary glands Parasympathetic ganglia (within the walls of organs) Sympathetic trunk Stellate ganglion* Cranial part: brainstem with parasympathetic nuclei CN IX Cranial vessels CN X Heart T1 T2 T3 T4 T5 T6 Greater splanchnic n. Celiac ganglion T7 T8 Lung Stomach Liver Pancreas T9 Kidney T 10 T 11 Intestine T 12 L1 Superior mesenteric ganglion L2 Inferior mesenteric ganglion L3 Parts of the colon, rectum L4 L5 Bladder Genitalia A **Inferior hypogastric plexus *Stellate ganglion - inferior cervical ganglion and T1 sympathetic ganglion **Minimal sympathetic preganglionic fibers traveling through the sacral splanchnic nerves will synapse in the ganglia located in the inferior hypogastric plexus. 694 Pelvic splanchnic nn. S1 S2 S3 S4 S5 Sacral part: sacral cord with parasympathetic nuclei B Parasympathetic pathways Neuron Location of cell body Upper motor neuron Hypothalamus: The cell bodies of parasympathetic upper motor neurons are located in the hypothalamus. Their axons descend via white matter tracts to synapse with the lower motor neuron in the brainstem and sacral spinal cord (S2–S4). Preganglionic neuron (lower motor neuron) The parasympathetic nervous system is divided into two parts (cranial and sacral), based on the location of the preganglionic parasympathetic neurons. Brainstem cranial nerve nuclei: The axons of these secondary neurons leave the CNS as the motor root of cranial nn. III, VII, IX, and X. Spinal cord (S2–S4): The axons of the sacral parasympathetics originate from the S2–S4 spinal segments in a region of the spinal cord gray matter similar to that of the lateral horns where the sympathetic division arises from. These axons initially travel through the S2–S4 anterior roots before con-tinuing within the S2–S4 anterior rami. The axons then pass through pelvic splanchnic nerves that arise from the S2–S4 anterior rami before reaching the inferior hypogastric plexus, which then distributes the axons to the pelvic and hindgut structures. Postganglionic neuron Cranial nerve parasympathetic ganglia: The parasympathetic cranial nn. of the head each have at least one ganglion: • CN III: Ciliary ganglion • CN VII: Pterygopalatine ganglion and submandibular ganglion • CN IX: Otic ganglion • CN X: Small unnamed (intramural) ganglia close to target structures Distribution of postganglionic fibers Parasympathetic fibers course with other fiber types to their targets. In the head, the postganglionic fibers from the pterygopalatine ganglion (CN VII) and otic ganglion (CN IX) are distributed via branches of the trigeminal n. (CN V). Postganglionic fibers from the ciliary ganglion (CN III) course with sympathetic and sensory fibers in the short ciliary nn. (preganglionic fibers travel with the somatomotor fibers of CN III). In the thorax, abdomen, and pelvis, preganglionic parasympathetic fibers from CN X and the pelvic splanchnic nn. combine with postganglionic sympathetic fibers to form plexuses (e.g., cardiac, pulmonary, esophageal). Table 50.2 50 Autonomic Nervous System Table 50.1 Sympathetic pathways Neuron Location of cell body Upper motor neuron Hypothalamus: The cell bodies of sympathetic upper motor neurons are located in the hypothalamus. Their axons descend via white matter tracts to synapse with the lower motor neuron in the lateral horn of the spinal cord (T1–L2). Preganglionic neuron (lower motor neuron) Intermediolateral gray horn of spinal cord (T1–L2): The lateral horn is the middle portion of the gray matter of the spinal cord, situated between the anterior and posterior horns. It contains exclusively autonomic (sympathetic) neurons. The axons of these neurons leave the CNS as the motor root of the spinal nn. and enter the paravertebral ganglia via the white rami communicans (myelinated). Preganglionic neurons in paravertebral ganglia All preganglionic sympathetic neurons enter the sympathetic chain. There they may synapse in a chain ganglion or ascend or descend to synapse. Preganglionic sympathetic neurons synapse in one of two places, yielding two types of sympathetic ganglia. Synapse in the paravertebral ganglia Pass without synapsing through the sympathetic ganglia. These fibers travel in the thoracic, lumbar, and sacral splanchnic nn. to synapse in the prevertebral ganglia. Postganglionic neuron Paravertebral ganglia: These ganglia form the sympathetic nerve trunks that flank the spinal cord. Postganglionic axons leave the sympathetic trunk via the gray rami communicans (unmyelinated). Prevertebral ganglia: Associated with peripheral plexuses, which spread along the abdominal aorta. There are three primary prevertebral ganglia: • Celiac ganglion • Superior mesenteric ganglion • Inferior mesenteric ganglion Distribution of postganglionic fibers Postganglionic fibers are distributed in two ways: 1. Spinal nerves: Postganglionic neurons may re-enter the spinal nn. via the gray rami communicans. These sympathetic neurons induce constriction of blood vessels of the skin and dilate the blood vessels of skeletal muscles, sweat glands, and arrector pili (muscle fibers attached to hair follicles, “goose bumps”). 2. Arteries and ducts: Nerve plexuses may form along existing structures. Postganglionic sympathetic fibers may travel with arteries to target structures. Viscera are innervated by this method (e.g., sympathetic innervation concerning vasoconstriction, bronchial dilatation, glandular secretions, pupillary dilatation, smooth muscle contraction). 695 Brain & Nervous System Autonomic Nervous System (II) Fig. 50.2 Typical spinal nerve All spinal nerves arising from the spinal cord contain somatic sensory (or afferent, from body wall) and somatic motor (or efferent, to body wall) fibers. Sensory fibers come from the posterior (back) region via the posterior ramus and anterolateral regions of the body wall via the anterior ramus of the spinal nerve. The somatic sensory fibers approach the spinal cord via the posterior root. The cell bodies for these fibers lie in the sensory (spinal/dorsal root) ganglion. They synapse with sensory Sensory (spinal) ganglion neurons in the posterior horn of gray matter within the spinal cord sending the majority to the brain for interpretation. Somatic motor fibers have their neurons in the anterior horn of gray matter and send their fibers to the spinal n. via the anterior root. This pattern of somatic innervation occurs in all spinal nerves from C1 through S5, whether they are involved in a plexus or not. Posterior root Spinal n. Spinal Cord Level L2 Posterior ramus Anterior ramus Anterior root Spinal Cord Level L3 Somatic sensory (afferent) Somatic motor (efferent) Fig. 50.3 ANS Circuitry Body wall dermatomes also require sympathetic fibers to contract smooth muscle and cause glands in the dermatome to secrete. Preganglionic sympathetic fibers (purple) arise from cell bodies in the intermediolateral gray horn of the spinal cord. They exit the spinal cord via the outgoing/efferent (anterior) root—along with the somatic motor (efferent) fibers—and enter the spinal nerve. The smooth muscle of the body wall requires innervation by postganglionic sympathetic fibers so the preganglionic fiber looks for the closest synapse site—the paravertebral sympathetic ganglia—found in a chain-like arrangement on either side of the vertebral column. Each ganglion is connected to the spinal n. by communicating branches—the rami communicans. The white ramus communicans is found most lateral and conveys the preganglionic (myelinated = white) sympathetic fiber to the ganglion. Once in the paravertebral ganglion one of two things can happen: a) The preganglionic sympathetic fiber can synapse in the ganglion and the postganglionic sympathetic fiber (orange) passes along the gray ramus communicans (unmyelinated) back to the spinal n. Now postganglionic sympathetic fibers can be distributed to structures 696 in the dermatome via the anterior and posterior rami—along with somatic motor and sensory fibers. b) The preganglionic fiber can run up or down the sympathetic trunk to synapse in an upper or lower paravertebral ganglion. This is especially important as the source of sympathetic innervation is limited to spinal cord levels T1 to L2. This figure depicts sympathetic innervation from the last spinal cord segment to contain it (L2) descending along the sympathetic trunk to the paravertebral ganglion at L3. It synapses here and the postganglionic sympathetic fiber exits into the spinal nerve of L3. Note that there is only a gray ramus communicans at this level as white rami communicans are input fibers (T1–L2), while the gray are output fibers above and below T1 and L2. Therefore, there are more gray rami than white rami. Both anterior and posterior rami now contain postganglionic sympathetic fibers distributed to the dermatome of L3 along with the typical somatic sensory and motor fibers of each vertebral level. Now that the body wall has been supplied with postganglionic sympathetic innervation, we’ll turn our attention to the viscera. In the tiny parasympathetic (intramural) ganglion within the wall of the organ. The postganglionic parasympathetic fibers (light blue) are therefore extremely short. The remainder of the abdominal and pelvic viscera receive their parasympathetic supply in a similar fashion but from preganglionic parasympathetic fibers from spinal cord levels S2-4. Viscera also exhibit pain, relayed back to the CNS as visceral afferents (dark green). Note that the visceral afferent fibers follow the pathway of the sympathetic pre- and postganglionic fibers back from the viscera. They pass through the prevertebral ganglion (without synapsing), and then back along the splanchnic n. and through the paravertebral ganglion (again, without synapsing). From there they travel along the white ramus communicans (as visceral afferent fibers, they are also myelinated) and follow the posterior root back to the sensory ganglion where the cell body is found interspersed amongst those for the body wall. They finally synapse in the posterior horn of gray matter in the spinal cord amongst the somatic afferents also synapsing there. This is the basis for referred pain as the brain finds it difficult to distinguish visceral pain from somatic pain as the latter outnumber the former very significantly. Therefore, pain from internal organs is often referred to sites on the body wall. 50 Autonomic Nervous System third option for preganglionic sympathetic fibers entering a prevertebral ganglion, the fibers pass through the paravertebral ganglion at that level without synapsing and pass into a splanchnic n. to synapse in one of 3 primary prevertebral (or collateral) ganglia found in the abdomen along the anterior surface of the aorta at the base of one of the three main visceral branches (celiac a., superior mesenteric a., and inferior mesenteric a.). The postganglionic sympathetic fibers (orange) are distributed by following arterial branches to the viscera where they decrease the activity of the glands and peristalsis, constrict sphincters, and vasoconstrict the blood vessels. The body wall does not receive any parasympathetic innervation. Dilation of the blood vessel walls occurs as the postganglionic sympathetics stop firing to cause vasoconstriction. However, the intricate control of movement of the wall of the intestine, or secretion of the glands within its wall, does require the antagonistic input of the parasympathetic division. Parasympathetic innervation to the viscera of the thorax and much of the abdomen (to the mid transverse colon) is supplied by the vagus n. (dark blue). The vagus n. sends branches to the various sympathetic prevertebral ganglia of the abdomen but they do not synapse there. They pass through, following the branches of the blood vessel to the wall of the organs supplied. There they synapse in Somatic afferent (sensory) Somatic efferent (motor) Sympathetic, preganglionic Sympathetic, postganglionic Parasympathetic, preganglionic Parasympathetic, postganglionic Visceral afferent (sensory) Sensory (spinal) ganglion Posterior root Brain stem Spinal n. - L2 Posterior ramus Anterior ramus Gray ramus communicans Anterior root White ramus communicans Spinal cord level L2 Vagus n. (CN X) (preganglionic parasympathetic) Splanchnic n. Prevertebral (collateral) ganglion Paravertebral (sympathetic) ganglion Spinal n. - L3 Wall of small intestine Gray ramus communicans Sympathetic trunk Intramural (terminal) ganglion 697 51 Sectional & Radiographic Anatomy Brain & Nervous System Sectional Anatomy of the Nervous System Fig. 51.1 Sagittal section through the midline of the brain Anterior commissure Corpus callosum, genu Cingulate gyrus Interventricular Septum foramen pellucidum Corpus callosum, trunk Fornix Third ventricle Corpus callosum, splenium Parieto-occipital sulcus Calcarine sulcus Pineal Tectal plate Anterior lobe of cerebellum Optic chiasm Hypothalamus Infundibulum Primary fissure Hypophysis Cerebral peduncle (crus cerebri) Cerebral aqueduct Pons Fourth ventricle Lingula Inferior medullary velum Medulla oblongata Uvula Nodule Superior medullary velum Central canal Fig. 51.2 Frontal section through the brain I Lateral ventricle, central part Longitudinal cerebral fissure Caudate nucleus, body Corpus callosum, trunk Internal capsule, posterior limb Choroid plexus of lateral ventricle Insula Medial geniculate body Fornix, crus Thalamic nuclei Lateral geniculate body Caudate nucleus, tail Hippocampus Fimbria of hippocampus Choroid plexus of lateral ventricle Posterior commissure Dentate gyrus Anterior lobe of cerebellum Third ventricle Superior cerebellar peduncle Horizontal fissure Middle cerebellar peduncle Flocculus Medulla oblongata 698 F