MRCS ANATOMY NOTES - REDA 1a. Head and Neck 3 Foramina of the Base of the Skull 4 Visual Field Defects 6 Cranial Venous Sinuses 8 Cavernous Sinus 9 Sternocleidomastoid 10 Scalene Muscles 11 Anterior Triangle of the Neck 12 Posterior Triangle of the Neck 13 Parathyroid Glands - Anatomy 14 Thyroid Gland 15 The Tongue 16 Submandibular Gland 18 Parotid Gland 19 Circle of Willis 20 Vertebral Artery 21 Common Carotid Artery 22 Internal Carotid Artery 23 External Carotid Artery 24 Middle Meningeal Artery 25 Brachiocephalic Artery 26 Subclavian Artery 26 Internal Jugular Vein 27 Cranial Nerves 28 Trigeminal Nerve 30 Facial Nerve 32 Vagus Nerve 36 Recurrent Laryngeal Nerve 38 Ansa Cervicalis 39 Ear Anatomy 40 Lacrimal System 42 Tonsil 43 Surface Anatomy 44 1b. Abdomen 45 Abdominal wall 46 External oblique muscle 47 Inguinal canal 49 Scrotal and testicular anatomy 51 Colon anatomy 52 Caecum 55 Transverse colon 55 Left colon 56 Rectum 56 Anal sphincter 57 Spleen 58 Liver 59 Gallbladder 61 Pancreas 62 Abdominal aorta 63 Abdominal aortic branches 64 Coeliac axis 65 Gastroduodenal artery 65 Inferior mesenteric artery 66 Renal anatomy 67 Ureter 68 Adrenal gland anatomy 69 Prostate gland 70 Epiploic (Omental) Foramen 71 Inferior vena cava 72 Diaphragm apertures 73 Uterus 74 1c. Thorax 75 Mediastinum 76 Sternal Angle 77 Trachea 78 Oesophagus 79 Lung Anatomy 80 Phrenic Nerve 82 Thoracic Duct 83 Heart Anatomy 84 Superior Vena Cava 86 Thoracic Aorta 87 Prosthetic Heart Valves On Chest X-Rays 87 1d. Upper Limb 89 Bones of the UL 90 Muscles of the UL 96 Muscles of the Shoulder 96 Muscles of the Arm and Forearm 98 Extensor Retinaculum / Dorsal Wrist Compartments 103 Neuroanatomic Relationships in the Forearm 103 Muscles of the Hand and Wrist 104 Hand 105 Interossei 107 Anatomical snuffbox 108 Arteries of the UL 109 Axillary Artery 109 Thoracoacromial Artery 109 Brachial Artery 111 Ulnar Artery 112 Radial Artery 112 Veins of the UL Basilic Vein Nerves of the UL 113 113 115 Brachial Plexus 116 Summary of Upper Extremity Innervation 117 Musculocutaneous Nerve 118 Median Nerve 118 Ulnar Nerve 119 Radial Nerve 122 Joints of the UL 124 Shoulder Joint 124 Important Regions of the UL 126 Breast 126 Axilla 128 Cubital Fossa 129 Surface Anatomy 1e. Lower Limb 130 132 Bones of the Pelvis and Lower Limbs 133 Muscles of LL 140 Gluteal Region 140 Muscles Of The Pelvis And Hip 141 Muscles Of The Thigh 145 Muscles Of The Leg 148 Muscles Of The Ankle And Foot 151 Greater Sciatic Foramen 153 Fascial Compartments Of The Leg 154 Arteries of LL 155 Anterior Tibial Artery 155 Posterior Tibial Artery 155 Femoral Artery 157 Veins of LL 160 Saphenous Vein Nerves of LL 160 161 Genitofemoral Nerve 163 Pudendal Nerve 164 Femoral Nerve 165 Obturator Nerve 166 Sciatic Nerve 167 Common Peroneal (Common Fibular) (Lat. Popliteal) Nerve 169 Deep Peroneal (Deep Fibular) (Ant. Tibial) Nerve 170 Important Regions 171 Femoral Triangle Anatomy 171 Femoral Canal 172 Adductor Canal 172 Popliteal Fossa 173 Pudendal (Alcock’s) Canal 173 Foot - Anatomy 175 Joints of LL 178 Hip Joint 178 Knee Joint 179 Ankle Joint 183 Surface Anatomy 1f. Miscellaneous 185 186 Lumbar puncture 187 Vertebral column 188 Spinal cord 189 Upper Vs Lower motor neurone lesions - Facial nerve 190 Sympathetic Nervous System - Anatomy 191 Pharyngeal arches 192 Levels 193 MRCS Part A Notes This is a just summary of short notes for the MRCS part A exam, they are NOT meant to replace any text books or references. Merely intended for a quick read with common question topics and revision points for the exam. Taken mainly from eMRCS.com and reorganized with illustrations added (google search) and some info from other websites. Acknowledgements • eMRCS.com • medcomic.com • Gray’s Anatomy • Netter’s Anatomy series • Wikipedia.org • Various other sources… too many to mention or remember Mohamed Reda 1 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Foramina of the Base of the Skull .................................................................................................................. 2 Visual Field Defects ......................................................................................................................................... 4 Cranial Venous Sinuses ................................................................................................................................... 6 Cavernous Sinus .............................................................................................................................................. 7 Sternocleidomastoid....................................................................................................................................... 8 Scalene Muscles .............................................................................................................................................. 9 Anterior Triangle of the Neck ....................................................................................................................... 10 Posterior Triangle of the Neck ...................................................................................................................... 11 Parathyroid Glands - Anatomy ..................................................................................................................... 12 Thyroid Gland................................................................................................................................................ 13 The Tongue.................................................................................................................................................... 14 Submandibular Gland ................................................................................................................................... 16 Parotid Gland ................................................................................................................................................ 17 Circle of Willis ............................................................................................................................................... 18 Vertebral Artery ............................................................................................................................................ 19 Common Carotid Artery ............................................................................................................................... 20 Internal Carotid Artery ................................................................................................................................. 21 External Carotid Artery ................................................................................................................................. 22 Middle Meningeal Artery ............................................................................................................................. 23 Brachiocephalic Artery ................................................................................................................................. 24 Subclavian Artery .......................................................................................................................................... 24 Internal Jugular Vein ..................................................................................................................................... 25 Cranial Nerves ............................................................................................................................................... 26 Trigeminal Nerve........................................................................................................................................... 28 Facial Nerve ................................................................................................................................................... 30 Vagus Nerve .................................................................................................................................................. 34 Recurrent Laryngeal Nerve ........................................................................................................................... 36 Ansa Cervicalis .............................................................................................................................................. 37 Ear Anatomy.................................................................................................................................................. 38 Lacrimal System ............................................................................................................................................ 40 Tonsil ............................................................................................................................................................. 41 Surface Anatomy........................................................................................................................................... 42 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 1 Foramina of the Base of the Skull Foramen Foramen ovale 2 Location Sphenoid bone Contents Otic ganglion V 3 (Mandibular nerve:3rd branch of trigeminal) “OVALE” Accessory meningeal artery Lesser petrosal nerve Emissary veins Foramen spinosum Sphenoid bone Middle meningeal artery Meningeal branch of the Mandibular nerve Foramen rotundum Sphenoid bone Maxillary nerve (V 2 ) Foramen lacerum / Sphenoid bone Base of the medial pterygoid plate. carotid canal Internal carotid artery* Nerve and artery of the pterygoid canal Jugular foramen Temporal Anterior: inferior petrosal sinus bone Intermediate: glossopharyngeal, vagus, and accessory nerves. (9, 10, 11) Posterior: sigmoid sinus (becoming the internal jugular vein) and some meningeal branches from the occipital and ascending pharyngeal arteries. Foramen magnum Occipital bone Anterior and posterior spinal arteries Vertebral arteries Medulla oblongata Stylomastoid Temporal Stylomastoid artery foramen bone Facial nerve Superior orbital Sphenoid bone Lacrimal branch of ophthalmic nerve (V 1 ) fissure Frontal branch of ophthalmic nerve (V 1 ) Recurrent meningeal artery “Live FRankly To See Trochlear (IV) Absolutely No Superior Division of Oculomotor (III), Superior ophthalmic vein Insult” Abducens (VI) (3, 4, 5 1 , 6, SR) Nasociliary branch of ophthalmic nerve (V 1 ) Inferior Division of Oculomotor nerve (III) *= In life the foramen lacerum is occluded by a cartilagenous plug. The ICA initially passes into the carotid canal which ascends superomedially to enter the cranial cavity through the foramen lacerum. NB. The hypoglossal nerve passes through the hypoglossal canal. The optic canal transmits the optic nerve. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 2 Foramen rotundum: (middle cranial fossa/ pterygopalatine fossa) • [V2] Maxillary division of [V] (trigeminal nerve) Foramen ovale: (middle cranial fossa/ infratemporal fossa) • [V3] Mandibular division of [V] (trigeminal nerve) Carotid canal: (middle cranial fossa/ neck) • Internal carotid artery Foramen spinosum: (middle cranial fossa/ infratemporal fossa) • Middle meningeal artery Jugular foramen: (posterior cranial fossa/ neck) • [IX] Glossopharyngeal nerve • [X] Vagus nerve • [XI] Accessory nerve • Internal jugular vein Foramen magnum: (posterior cranial fossa/ neck) • Spinal cord • Vertebral arteries Roots of accessory nerve [XI] pass from upper region of spinal cord through the foramen magnum into the cranial cavity and then leave the cranial cavity though the jugular foramen Carotid canal: • Internal carotid artery Stylomastoid foramen: • [VII] Facial nerve 3 Cribriform plate: (anterior cranial fossa/ nasal cavity) • [I] Olfactory nerves Optic canal: (middle cranial fossa/ orbit) • [II] Optic nerve • Ophthalmic artery Superior orbital fissure: (middle cranial fossa/ orbit) • [V1] Ophthalmic division of [V] (trigeminal nerve) • [III] Oculomotor nerve • [IV] Trochlear nerve • [VI] Abducent nerve • Superior ophthalmic vein Foramen lacerum: (filled with cartilage in life) Internal acoustic meatus: (posterior cranial fossa/ear, and neck via stylomastoid foramen) • [VII] Facial nerve • [VIII] Vestibulocochlear nerve • Labyrinthine artery and vein Hypoglossal canal: (posterior cranial fossa/ neck) • [XII] Hypoglossal nerve Foramen ovale: • [V3] Mandibular division of [V] (trigeminal nerve) Foramen spinosum: • Middle meningeal artery Hypoglossal canal: • [XII] Hypoglossal nerve Jugular foramen: (posterior cranial fossa/ neck) • [IX] Glossopharyngeal nerve • [X] Vagus nerve • [XI] Accessory nerve • Internal jugular vein Foramen magnum: (posterior cranial fossa/ neck) • Spinal cord • Vertebral arteries 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 3 4 Visual Field Defects • • • Left homonymous hemianopia means visual field defect to the left, i.e. Lesion of right optic tract Homonymous quadrantanopias: PITS (Parietal-Inferior, Temporal-Superior) Incongruous defects = optic tract lesion; congruous defects = optic radiation lesion or occipital cortex Homonymous hemianopia • Incongruous defects: lesion of optic tract • Congruous defects: lesion of optic radiation or occipital cortex • Macula sparing: lesion of occipital cortex Lesions before optic chiasm: Monocular vision loss = Optic nerve lesion Bitemporal hemianopia = Optic chiasm lesion Homonymous quadrantanopia • Superior: lesion of temporal lobe • Inferior: lesion of parietal lobe • Mnemonic = PITS (Parietal-Inferior, Temporal-Superior) Lesions after the optic chiasm: Homonymous hemianopia = Optic tract lesion Upper quadrantanopia = Temporal lobe lesion Lower quadrantanopia = Parietal lobe lesion Bitemporal hemianopia • Lesion of optic chiasm • Upper quadrant defect > Lower quadrant defect = inf. chiasmal compression, commonly a pituitary tumour • Lower quadrant defect > Upper quadrant defect = sup. chiasmal compression, commonly a craniopharyngioma 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 4 5 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 5 Cranial Venous Sinuses 6 The cranial venous sinuses are located within the dura mater. They have no valves which is important in the potential for spreading sepsis. They eventually drain into the internal jugular vein. They are: • Superior sagittal sinus • Inferior sagittal sinus • Straight sinus • Transverse sinus • Sigmoid sinus • Confluence of sinuses • Occipital sinus • Cavernous sinus 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 6 7 Cavernous Sinus The cavernous sinuses are paired and are situated on the body of the sphenoid bone. It runs from the superior orbital fissure to the petrous temporal bone. Contents: “O TOM CAT” Lateral wall components Contents of the sinus (from top to bottom:) Oculomotor nerve (III) Trochlear nerve (IV) Ophthalmic nerve (V 1 ) Maxillary nerve (V 2) (from medial to lateral:) Internal Carotid artery (and sympathetic plexus) Abducens nerve (VI) Cavernous sinus syndrome is most commonly caused by cavernous sinus tumours. Diagnosis is based on signs of pain, ophthalmoplegia, proptosis, trigeminal nerve lesion (ophthalmic branch) and Horner's syndrome. Relations Medial Pituitary fossa Sphenoid sinus Lateral Temporal lobe Blood supply Ophthalmic vein, superficial cortical veins, basilar plexus of veins posteriorly. Drains into the internal jugular vein via: the superior and inferior petrosal sinuses 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 7 8 Sternocleidomastoid Anatomy Origin Rounded tendon attached to upper manubrium sterni and muscular head attached to medial third of the clavicle Insertion Mastoid process of the temporal bone and lateral area of the superior nuchal line of the occipital bone Innervation Spinal part of accessory nerve and anterior rami of C2 and C3 (proprioception)* Action • Both: extend the head at atlanto-occipital joint and flex the cervical vertebral column. Accessory muscles of inspiration. • Single: lateral flexion of neck, rotates head so face looks upward to the opposite side *The motor supply to the sternocleidomastoid is from the accessory nerve. The ansa cervicalis supplies sensory information from the muscle. Sternocleidomastoid divides the anterior and posterior triangles of the neck. Sternocleidomastoid Levator scapulae muscle Anterior scalene muscle Middle scalene muscle Inferior belly of omohyoid Trapezius Ant midline of the neck Superior thoracic aperture 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Clavicle 8 9 Scalene Muscles The 3 paired muscles are: • Scalenus anterior: Elevate 1st rib and laterally flex the neck to same side • Scalenus medius: Same action as scalenus anterior • Scalenus posterior: Elevate 2nd rib and tilt neck to opposite side Innervation Origin Insertion Important relations Spinal nerves C4-6 Transverse processes C2 to C7 First and second ribs • The brachial plexus and subclavian artery pass between the anterior and middle scalenes through a space called the scalene hiatus/fissure. • The subclavian vein and phrenic nerve pass anteriorly to the anterior scalene as it crosses over the first rib. Rectus capitis anterior muscle Rectus capitis lateral muscle Anterior scalene Middle scalene Posterior scalene Thoracic outlet syndrome The scalenes are at risk of adhering to the fascia surrounding the brachial plexus or shortening causing compression of the brachial plexus when it passes between the clavicle and 1st rib causing thoracic outlet syndrome. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 9 Anterior Triangle of the Neck 10 Boundaries • Anterior border of the Sternocleidomastoid • Lower border of mandible • Anterior midline Sub triangles (divided by Digastric above and Omohyoid) • Submandibular Triangle (Digastric) • Muscular triangle: Neck strap muscles • Carotid triangle: Carotid sheath Contents of the anterior triangle Digastric triangle Submandibular gland (submandibular) Submandibular nodes Facial vessels Hypoglossal nerve Muscular Strap muscles triangle External jugular vein Carotid triangle Carotid sheath (Common carotid, Vagus and IJV) Ansa cervicalis Nerve supply to digastric muscle • Anterior: Mylohyoid nerve • Posterior: Facial nerve Stylohyoid muscle Submandibular triangle Posterior belly of digastric Anterior belly of digastric muscle Hyoid bone Muscular triangle Superior belly of omohyoid 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 10 11 Boundaries Posterior Triangle of the Neck Apex Sternocleidomastoid and the Trapezius muscles at the Occipital bone Anterior Posterior border of the Sternocleidomastoid Posterior Anterior border of the Trapezius Base Middle third of the clavicle Nerves • • • • Contents Accessory nerve Phrenic nerve Three trunks of the brachial plexus Branches of the cervical plexus: Supraclavicular nerve, transverse cervical nerve, great auricular nerve, lesser occipital nerve Vessels • External jugular vein • Subclavian artery (3rd part) Muscles • Inferior belly of omohyoid • Scalene Lymph nodes • Supraclavicular • Occipital The IJV does not lie in the posterior triangle. However, the terminal branches of the external jugular vein do. Retromandibular vein Lesser occipital nerve Great auricular nerve Supraclavicular nerves 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 11 Parathyroid Glands - Anatomy • • • 12 Four parathyroid glands Located posterior to the thyroid gland They lie within the pretracheal fascia Embryology The parathyroids develop from the extremities of the third and fourth pharyngeal pouches. The parathyroids derived from the fourth pharyngeal pouch are located more superiorly and are associated with the thyroid gland. Those derived from the third pharyngeal pouch lie more inferiorly and may become associated with the thymus. Blood supply The blood supply to the parathyroid glands is derived from the inferior and superior thyroid arteries (Thyrocervical trunk and the ECA respectively). There is a rich anastomosis between the two vessels. Venous drainage is into the thyroid veins. Relations Laterally Medially Anterior Posterior Common carotid Recurrent laryngeal nerve, trachea Thyroid Pretracheal fascia Thyrohyoid Inferior thyroid a. Left subclavian a. Thyrocervical trunk Right recurrent laryngeal nerve Inferior thyroid veins 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 12 13 Thyroid Gland • • • • • Right and left lobes connected by isthmus Surrounded by sheath from pretracheal layer of deep fascia Apex: Lamina of thyroid cartilage. Base: 4th-5th tracheal ring Pyramidal lobe: from isthmus. Mnemonic “Rings 2,3,4 make the isthmus floor” May be attached to foramen caecum at the base of the tongue Relations Anteromedially Posterolaterally Medially Posterior Isthmus Blood Supply Arterial Venous • Sternothyroid • Sternohyoid • Superior belly of omohyoid • Anterior aspect of sternocleidomastoid Carotid sheath (CCA, IJV, X) • Larynx • Oesophagus • External laryngeal nerve (near superior thyroid a.) • Trachea • Cricothyroid • Recurrent laryngeal nerve (near inferior thyroid a.) muscle • Pharynx • Parathyroid glands • Anastomosis of superior and inferior thyroid arteries • Anteriorly: Sternothyroid, sternohyoid, anterior jugular veins • Posteriorly: 2nd, 3rd, 4th tracheal rings (attached via Ligament of Berry) • • • • • Superior thyroid artery (1st branch of external carotid) Inferior thyroid artery (from thyrocervical trunk from subclavian a. 1st part) Thyroidea ima (in 10% of population -from brachiocephalic artery or aorta) Superior and middle thyroid veins - into the IJV Inferior thyroid vein - into the brachiocephalic veins Pretracheal fascia Trachea Pyramidal lobe Thyroid gland Right recurrent laryngeal nerve Common carotid artery Left lobe thyroid Right internal jugular vein 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Left internal jugular vein 13 14 The Tongue Lymphatic Drainage • The lymphatic drainage of the anterior two thirds of the tongue shows only minimal communication of lymphatics across the midline, so metastasis to the ipsilateral nodes is usual. • The lymphatic drainage of the posterior third of the tongue have communicating networks, as a result early bilateral nodal metastases are more common in this area. • Lymphatics from the tip of the tongue usually pass to the sub mental nodes and from there to the deep cervical nodes. • Lymphatics from the mid portion of the tongue usually drain to the submandibular nodes and then to the deep cervical nodes. Mid tongue tumours that are laterally located will usually drain to the ipsilateral deep cervical nodes, those from more central regions may have bilateral deep cervical nodal involvement. Motor Innervation All of the motor innervation is provided by Hypoglossal (XII) except for the palatoglossus muscle which is provided by Vagus (X). Sensory and taste Innervation Area Sensory Innervation Gustatory (taste) Innervation Vagus (X) Glossopharyngeal (IX)* Mandibular (V 3 ) via Lingual Facial (VII) via Chorda tympani Supplies general sensation to the posterior third of the tongue and contributes to the gag reflex. Posterior part of the root of tongue Posterior 1/3 Anterior 2/3 Sensory Anterior two-thirds (oral) • General sensation mandibular Posterior one-third (pharyngeal) nerve [V3] via lingual nerve • General and special (taste) • Special sensation (taste) sensation via facial nerve [VII] via chorda glossopharyngeal nerve [IX] tympani Glossopharyngeal nerve [IX] Chorda tympani (from [VII]) Lingual nerve (from [V3]) Motor Hypoglossal nerve [XII] Deep lingual vein Dorsal lingual vein Lingual artery Intrinsic muscle Genioglossus Palatoglossus vagus nerve [X] 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Common carotid artery Internal jugular vein Sternocleidomastoid branch of occipital artery 14 15 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 15 Submandibular Gland 16 Deep Superficial Relations of the submandibular gland Platysma, deep fascia and mandible Submandibular lymph nodes Facial vein (facial artery near mandible) Marginal mandibular nerve (of facial n.) Cervical branch of the facial nerve Facial artery (inferior to the mandible) Mylohyoid muscle Sub mandibular duct Hyoglossus muscle Lingual nerve Submandibular ganglion Hypoglossal nerve Submandibular duct (Wharton's duct) • Opens lateral to the lingual frenulum on the anterior floor of mouth. • 5 cm length • Lingual nerve wraps around Wharton's duct. As the duct passes forwards it crosses medial to the nerve to lie above it and then crosses back, lateral to it, to reach a position below the nerve. Innervation • Sympathetic innervation- Derived from superior cervical ganglion • Parasympathetic innervation- Submandibular ganglion via lingual nerve Arterial supply Branch of the facial artery. The facial artery passes through the gland to groove its deep surface. It then emerges onto the face by passing between the gland and the mandible. Venous drainage Anterior facial vein (lies deep to the Marginal Mandibular nerve) Lymphatic drainage Deep cervical and jugular chains of nodes Three cranial nerves may be injured during submandibular gland excision. • Marginal mandibular branch of the facial nerve • Lingual nerve • Hypoglossal nerve Hypoglossal nerve damage may result in paralysis of the ipsilateral aspect of the tongue. The nerve itself lies deep to the capsule surrounding the gland and should not be injured during an intracapsular dissection. The lingual nerve is probably at greater risk of injury. However, the effects of lingual nerve injury are sensory rather than motor. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 16 17 Parotid Gland Anatomy of the parotid gland Location Overlying the mandibular ramus; anterior and inferior to the ear. Salivary duct Crosses the masseter, pierces the buccinator and drains adjacent to the 2nd upper molar tooth (Stensen's duct). Structures passing through • Facial nerve (most superficial structure) the gland (“The Zebra Buggered My Cat” Temporal Zygomatic, Buccal, Mandibular, Cervical) • External carotid artery • Retromandibular vein • Auriculotemporal nerve (from post. trunk of V 3 ) Relations • Anterior: masseter, medial pterygoid, superficial temporal and maxillary artery, facial nerve, stylomandibular ligament • Posterior: posterior belly digastric muscle, sternocleidomastoid, stylohyoid, internal carotid artery, mastoid process, styloid process Arterial supply Branches of external carotid artery Venous drainage Retromandibular vein Lymphatic drainage Deep cervical nodes Nerve innervation • Parasympathetic: Secretomotor (from otic ganglion) • Sympathetic: Superior cervical ganglion • Sensory: Greater auricular nerve Parasympathetic stimulation produces a water-rich, serous saliva. Sympathetic stimulation leads to the production of a low volume, enzyme-rich saliva. Maxillary artery and vein Transverse facial artery and vein Superficial temporal artery and vein Posterior auricular artery Retromandibular vein Buccinator Marginal mandibular branches Cervical branches 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 17 Circle of Willis 18 The two internal carotid arteries and two vertebral arteries form an anastomosis known as the Circle of Willis on the inferior surface of the brain. Each half of the circle is formed by: 1. Anterior communicating artery 2. Anterior cerebral artery 3. Internal carotid artery 4. Posterior communicating artery 5. Posterior cerebral arteries and the termination of the basilar artery The circle and its branches supply; the corpus striatum, internal capsule, diencephalon and midbrain. Vertebral arteries • Enter the cranial cavity via foramen magnum • Lie in the subarachnoid space • Ascend on anterior surface of medulla oblongata • Unite to form the basilar artery at the base of the pons Branches: • Posterior spinal artery • Anterior spinal artery • Posterior inferior cerebellar artery 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Basilar artery Branches: • Anterior inferior cerebellar artery • Labyrinthine artery • Pontine arteries • Superior cerebellar artery • Posterior cerebral artery Internal carotid arteries Branches: • Posterior communicating artery • Anterior cerebral artery • Middle cerebral artery • Anterior choroid artery 18 Vertebral Artery 19 The vertebral artery is the first branch of the subclavian artery. Anatomically it is divisible into 4 regions: • The first part runs to the foramen in the transverse process of C6. Anterior to this part lies the vertebral and internal jugular veins. On the left side the thoracic duct is also an anterior relation. • The second part runs superiorly through the foramina of the transverse processes of the upper 6 cervical vertebrae. Once it has passed through the transverse process of the axis it then turns superolaterally to the atlas. It is accompanied by a venous plexus and the inferior cervical sympathetic ganglion. • The third part runs posteromedially on the lateral mass of the atlas. It enters the sub occipital triangle, in the groove of the upper surface of the posterior arch of the atlas. It then passes anterior to the edge of the posterior atlanto-occipital membrane to enter the vertebral canal. • The fourth part passes through the spinal dura and arachnoid, running superiorly and anteriorly at the lateral aspect of the medulla oblongata. At the lower border of the pons it unites to form the basilar artery. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 19 Common Carotid Artery 20 The right common carotid artery arises at the bifurcation of the brachiocephalic trunk. The left common carotid arises from the arch of the aorta. Both terminate at the level of the upper border of the thyroid cartilage C4/C3 (the lower border of the third cervical vertebra) by dividing into the internal and external carotid arteries. Left common carotid artery This vessel arises immediately to the left and slightly behind the origin of the brachiocephalic trunk. Its thoracic portion is 2.5- 3.5 cm in length and runs superolaterally to the sternoclavicular joint. In the thorax The vessel is in contact, from below upwards, with the trachea, left recurrent laryngeal nerve, left margin of the oesophagus. Anteriorly the left brachiocephalic vein runs across the artery, and the cardiac branches from the left vagus descend in front of it. These structures together with the thymus and the anterior margins of the left lung and pleura separate the artery from the manubrium. In the neck The artery runs superiorly deep to sternocleidomastoid and then enters the anterior triangle. At this point it lies within the carotid sheath with the vagus nerve and the internal jugular vein. Posteriorly the sympathetic trunk lies between the vessel and the prevertebral fascia. At the level of C7 the vertebral artery and thoracic duct lie behind it. The anterior tubercle of C6 transverse process is prominent and the artery can be compressed against this structure (it corresponds to the level of the cricoid). Anteriorly at C6 the omohyoid muscle passes superficial to the artery. Within the carotid sheath the jugular vein lies lateral to the artery. Right common carotid artery The right common carotid arises from the brachiocephalic artery. The right common carotid artery corresponds with the cervical portion of the left common carotid, except that there is no thoracic duct on the right. The oesophagus is less closely related to the right carotid than the left. Path Passes behind the sternoclavicular joint (12% patients above this level) to the upper border of the thyroid cartilage, to divide into the external (ECA) and internal carotid arteries (ICA). Relations • • • • Level of 6th cervical vertebra crossed by omohyoid Then passes deep to the thyrohyoid, sternohyoid, sternomastoid muscles. Passes ant. to the carotid tubercle (transverse process 6th cervical vertebra). NB: compression here stops hge. The inferior thyroid artery passes posterior to the common carotid artery. Then: o Left common carotid artery crosses the thoracic duct o Right common carotid artery crossed by recurrent laryngeal nerve 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 20 Internal Carotid Artery 21 The internal carotid artery is formed from the common carotid opposite the upper border of the thyroid cartilage. It extends superiorly to enter the skull via the carotid canal. From the carotid canal it then passes through the cavernous sinus, above which it divides into the anterior and middle cerebral arteries. Relations in the neck Posterior Medially Laterally Anteriorly • • • • • • • • • • • • Longus capitis Pre-vertebral fascia Sympathetic chain Superior laryngeal nerve External carotid (near origin) Wall of pharynx Ascending pharyngeal artery IJV (moves posteriorly at entrance to skull) Vagus nerve (most posterolaterally) Sternocleidomastoid Lingual and facial veins Hypoglossal nerve Mnemonic for branches of the cerebral portion of the internal carotid artery 'Only Press Carotid Arteries Momentarily' • Ophthalmic • Posterior communicating • Choroidal • Anterior cerebral • Middle cerebral Relations in the carotid canal • Internal carotid plexus • Cochlea and middle ear cavity • Trigeminal ganglion (superiorly) • Leaves canal lies above the foramen lacerum Path and relations in the cranial cavity The artery bends sharply forwards in the cavernous sinus, the adducent nerve lies close to its inferolateral aspect. The oculomotor, trochlear, ophthalmic and, usually, the maxillary nerves lie in the lateral wall of the sinus. Near the superior orbital fissure, it turns posteriorly and passes postero-medially to pierce the roof of the cavernous sinus inferior to the optic nerve. It then passes between the optic and oculomotor nerves to terminate below the anterior perforated substance by dividing into the anterior and middle cerebral arteries. Branches • Anterior and middle cerebral artery • Ophthalmic artery • Posterior communicating artery • Anterior choroid artery • Meningeal arteries • Hypophyseal arteries The internal carotid does not have any branches in the neck. Nerves at risk during carotid endarterectomy • Hypoglossal • Greater auricular • Superior laryngeal • Vagus 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 21 22 External Carotid Artery The external carotid commences immediately lateral to the pharyngeal side wall. It ascends and lies anterior to the internal carotid and posterior to the posterior belly of digastric and stylohyoid. More inferiorly it is covered by sternocleidomastoid, passed by hypoglossal nerves, lingual and facial veins. It then pierces the fascia of the parotid gland finally dividing into its terminal branches within the gland itself. Surface marking of the carotid This is an imaginary line drawn from the bifurcation of the common carotid passing behind the angle of the jaw to a point immediately anterior to the tragus of the ear. 'Some Angry Lady Figured Out PMS' (in order) Superior thyroid (superior laryngeal artery branch) Branches of the external carotid artery Ascending pharyngeal It has six main branches, three in front, two behind and one deep. Lingual Three in front Superior thyroid Facial (tonsillar and labial artery) Lingual Occipital Facial Two behind Occipital Posterior auricular Posterior auricular Maxillary (inferior alveolar artery, middle meningeal a.) Deep Ascending pharyngeal Superficial temporal It terminates by dividing into the superficial temporal and maxillary arteries in the parotid gland. Occipital artery Internal carotid artery Ascending pharyngeal artery External carotid artery Superior thyroid artery 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 22 Middle Meningeal Artery • • • • • 23 Middle meningeal artery is typically the third branch of the first part of the maxillary artery, one of the two terminal branches of the external carotid artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum to supply the dura mater (the outermost meninges). The middle meningeal artery is the largest of the three (paired) arteries which supply the meninges, the others being the anterior meningeal artery and the posterior meningeal artery. The middle meningeal artery runs beneath the pterion. It is vulnerable to injury at this point, where the skull is thin. Rupture of the artery may give rise to an extra dural hematoma. In the dry cranium, the middle meningeal, which runs within the dura mater surrounding the brain, makes a deep indention in the calvarium. The middle meningeal artery is intimately associated with the auriculotemporal nerve which wraps around the artery making the two easily identifiable in the dissection of human cadavers and also easily damaged in surgery. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 23 Brachiocephalic Artery 24 The brachiocephalic artery is the largest branch of the aortic arch. From its aortic origin it ascends superiorly, it initially lies anterior to the trachea and then on its right hand side. It branches into the common carotid and right subclavian arteries at the level of the sternoclavicular joint. Path Origin: apex of the midline of the aortic arch Passes superiorly and posteriorly to the right Divides into the right subclavian and right common carotid artery Relations Anterior Posterior Right lateral Left lateral • • • • • • • • • • • • • Sternohyoid Sternothyroid Thymic remnants Left brachiocephalic vein Right inferior thyroid veins Trachea Right pleura Right brachiocephalic vein Superior part of SVC Thymic remnants Origin of left common carotid Inferior thyroid veins Trachea (higher level) Branches Normally none but may have the thyroidea ima artery Subclavian Artery Path • The left subclavian comes directly off the arch of aorta • The right subclavian arises from the brachiocephalic artery (trunk) when it bifurcates into the subclavian and the right common carotid artery. • From its origin, the subclavian artery travels laterally, passing between anterior and middle scalene muscles, deep to scalenus anterior and anterior to scalenus medius. As the subclavian artery crosses the lateral border of the first rib, it becomes the axillary artery. At this point it is superficial and within the subclavian triangle. Branches “VIT C & D” • Vertebral artery • Internal thoracic artery • Thyrocervical trunk • Costocervical trunk • Dorsal scapular artery Ascending cervical artery Anterior scalene muscle Thyrocervical trunk Left subclavian a. Right subclavian a. Internal thoracic artery Rib I Left common carotid artery 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 24 Internal Jugular Vein 25 Each jugular vein begins in the jugular foramen, where they are the continuation of the sigmoid sinus. They terminate at the medial end of the clavicle where they unite with the subclavian v. The vein lies within the carotid sheath throughout its course. Below the skull the internal carotid artery and last four cranial nerves are anteromedial to the vein. Thereafter it is in contact medially with the internal (then common) carotid artery. The vagus lies posteromedially. At its superior aspect, the vein is overlapped by sternocleidomastoid and covered by it at the inferior aspect of the vein. Below the transverse process of the atlas it is crossed on its lateral side by the accessory nerve. At its mid-point it is crossed by the inferior root of the ansa cervicalis. Posterior to the vein are the transverse processes of the cervical vertebrae, the phenic nerve as it descends on the scalenus anterior, and the first part of the subclavian artery. On the left side it’s also related to the thoracic duct. The External Jugular vein runs obliquely in the superficial fascia of the posterior triangle. It drains in the subclavian vein. The 3rd part and not the 2nd part of the subclavian artery is also a content of the posterior triangle. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 25 Cranial Nerves 26 Cranial nerve lesions Olfactory nerve May be injured in basal skull fractures or involved in frontal lobe tumour extension. Loss of olfactory nerve function in relation to major CNS pathology is seldom an isolated event and thus it is poor localiser of CNS pathology. Optic nerve Problems with visual acuity may result from intra ocular disorders. Problems with the blood supply such as amaurosis fugax may produce temporary visual distortion. More important surgically is the pupillary response to light. The pupillary size may be altered in a number of disorders. Nerves involved in the resizing of the pupil connect to the pretectal nucleus of the high midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. From the pretectal nucleus neurones pass to the Edinger - Westphal nucleus, motor axons from here pass along with the oculomotor nerve. They synapse with ciliary ganglion neurones; the parasympathetic axons from this then innervate the iris and produce miosis. The miotic pupil is seen in disorders such as Horner's syndrome or opiate overdose. Mydriasis is the dilatation of the pupil in response to disease, trauma, drugs (or the dark!). It is pathological when light fails to induce miosis. The radial muscle is innervated by the sympathetic nervous system. Because the parasympathetic fibres travel with the oculomotor nerve they will be damaged by lesions affecting this nerve (e.g. cranial trauma). The response to light shone in one eye is usually a constriction of both pupils. This indicates intact direct and consensual light reflexes. When the optic nerve has an afferent defect the light shining on the affected eye will produce a diminished pupillary response in both eyes. Whereas light shone on the unaffected eye will produce a normal pupillary response in both eyes. This is referred to as the Marcus Gunn pupil and is seen in conditions such as optic neuritis. In a total CN II lesion shining the light in the affected eye will produce no response. Oculomotor The pupillary effects are described above. In addition, it supplies all ocular muscles apart from nerve lateral rectus and superior oblique. Thus the affected eye will be deviated inferolaterally. Levator palpebrae superioris may also be impaired resulting in impaired ability to open the eye. Trochlear nerve The eye will not be able to look down. Trigeminal nerve Largest cranial nerve. Exits the brainstem at the pons. Branches are ophthalmic, maxillary and mandibular. Only the mandibular branch has both sensory and motor fibres. Branches converge to form the trigeminal ganglion (located in Meckels cave). It supplies the muscles of mastication and also tensor veli palatine, mylohyoid, anterior belly of digastric and tensor tympani. Check textbook for detailed descriptions of the various sensory functions. The corneal reflex is important and is elicited by applying a small tip of cotton wool to the cornea, a reflex blink should occur if it is intact. It is mediated by: the naso ciliary branch of the ophthalmic branch of the trigeminal (sensory component) and the facial nerve producing the motor response. Lesions of the afferent arc will produce bilateral absent blink and lesions of the efferent arc will result in a unilateral absent blink. Abducens nerve The affected eye will have a deficit of abduction. This cranial nerve exits the brainstem between the pons and medulla. It thus has a relatively long intra cranial course which renders it susceptible to damage in raised intra cranial pressure. Facial nerve Emerges from brainstem between pons and medulla. It controls muscles of facial expression and taste from the anterior 2/3 of the tongue. The nerve passes into the petrous temporal bone and into the internal auditory meatus. It then passes through the facial canal and exits at the stylomastoid foramen. It passes through the parotid gland and divides at this point. It does not innervate the parotid gland. Its divisions are considered in other parts of the website. Its motor fibres innervate orbicularis oculi to produce the efferent arm of the corneal reflex. In surgical practice it may be injured during parotid gland surgery or invaded by malignancies of the gland and a lower motor neurone on the ipsilateral side will result. VestibuloExits from the pons and then passes through the internal auditory meatus. It is implicated in cochlear nerve sensorineural hearing loss. Individuals with sensorineural hearing loss will localise the sound in webers test to the normal ear. Rinnes test will be reduced on the affected side but should still work. These two tests will distinguish sensorineural hearing loss from conductive deafness. In the latter condition webers test will localise to the affected ear and Rinnes test will be impaired on the affected side. Surgical lesions affecting this nerve include CNS tumours and basal skull fractures. It may also be damaged by the administration of ototoxic drugs (of which gentamicin is the most commonly used in surgical practice). Glossopharyngeal Exits the pons just above the vagus. Receives sensory fibres from posterior 1/3 tongue, tonsils, nerve pharynx and middle ear (otalgia may occur following tonsillectomy). It receives visceral afferents from the carotid bodies. It supplies parasympathetic fibres to the parotid gland via the otic ganglion and motor function to stylopharyngeaus muscle. The sensory function of the nerve is tested using the gag reflex. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 26 Vagus nerve Accessory nerve Hypoglossal nerve 27 Leaves the medulla between the olivary nucleus and the inferior cerebellar peduncle. Passes through the jugular foramen and into the carotid sheath. Details of the functions of the vagus nerve are covered in the website under relevant organ sub headings. Exists from the caudal aspect of the brainstem (multiple branches) supplies trapezius and sternocleidomastoid muscles. The distal portion of this nerve is most prone to injury during surgical procedures. Emerges from the medulla at the preolivary sulcus, passes through the hypoglossal canal. It lies on the carotid sheath and passes deep to the posterior belly of digastric to supply muscles of the tongue (except palatoglossus). Its location near the carotid sheath makes it vulnerable during carotid endarterectomy surgery and damage will produce ipsilateral defect in muscle function. Cranial nerves carrying parasympathetic fibres X IX VII III (1973) The parasympathetic functions served by the cranial nerves include: III (oculomotor) Pupillary constriction and accommodation VII (facial) Lacrimal gland, submandibular and sublingual glands IX (glossopharyngeal) Parotid X (vagus) Heart and abdominal viscera The optic nerve carries no parasympathetic fibres. The cranial preganglionic parasympathetic nerves arise from specific nuclei in the CNS. These synapse at one of four parasympathetic ganglia; otic, pterygopalatine, ciliary and submandibular. From these ganglia the parasympathetic nerves complete their journey to their target tissues via CN V (trigeminal) branches (ophthalmic nerve CNV branch 1, Maxillary nerve CN V branch2, mandibular nerve CN V branch 3) [VIII] [IX] Trigeminal nerve [V] sensory root Trigeminal nerve [V] motor root [XI] 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 27 Trigeminal Nerve 28 The trigeminal nerve is the main sensory nerve of the head. In addition to its major sensory role, it also innervates the muscles of mastication. Distribution of the trigeminal nerve Sensory • Scalp • Face • Oral cavity (and teeth) • Nose and sinuses • Dura mater Motor • Muscles of mastication • Mylohyoid • Anterior belly of digastric • Tensor tympani • Tensor palati Autonomic • Ciliary connections • Sphenopalatine (ganglia) • Otic • Submandibular Path • • • Originates at the pons Sensory root forms the large, crescentic trigeminal ganglion within Meckel's cave, and contains the cell bodies of incoming sensory nerve fibres. Here the 3 branches exit. The motor root cell bodies are in the pons and the motor fibres are distributed via the mandibular nerve. The motor root is not part of the trigeminal ganglion. Branches of the trigeminal nerve Ophthalmic nerve Sensory only Maxillary nerve Sensory only Mandibular nerve Sensory and motor Sensory Ophthalmic Maxillary nerve Mandibular nerve Exit of branches of trigeminal nerve from the skull “Standing Room Only” V1 - Superior orbital fissure V2 - foramen Rotundum V3 - foramen Ovale Exits skull via the superior orbital fissure Sensation of: scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (via anterior ethmoidal from nasociliary, including the tip of the nose, except alae nasi), the nasal mucosa, the frontal sinuses, and parts of the meninges (the dura and blood vessels). Exit skull via the foramen rotundum Sensation: lower eyelid and cheek, the nares and upper lip, the upper teeth and gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses, and parts of the meninges. Exit skull via the foramen ovale Sensation: lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw), parts of the external ear, and parts of the meninges. Motor (Distributed via the mandibular nerve.) The following muscles of mastication are innervated: • Masseter • Temporalis • Medial pterygoid • Lateral pterygoid Other muscles innervated include: • Tensor veli palatini • Mylohyoid • Anterior belly of digastric • Tensor tympani 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA The trigeminal nerve is the major sensory nerve to the face except over the angle of the jaw which is supplied by the greater auricular nerve. The lateral aspect of the external nose is innervated by lateral nasal branches of the anterior ethmoidal nerve. The ethmoidal nerve is a branch of the nasociliary nerve (V1). 28 29 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 29 Facial Nerve 30 The facial nerve is the main nerve supplying the structures of the second embryonic branchial arch. It is predominantly an efferent nerve to the muscles of facial expression, digastric muscle and also to many glandular structures. It contains a few afferent fibres which originate in the cells of its genicular ganglion and are concerned with taste. Supply - 'Face, Ear, Taste, Tear' • Face: muscles of facial expression • Ear: nerve to stapedius • Taste: supplies anterior two-thirds of tongue • Tear: parasympathetic fibres to lacrimal glands, also salivary glands Path Subarachnoid path • Origin: motor- pons, sensory- nervus intermedius • Pass through the petrous temporal bone into the internal auditory meatus with the vestibulocochlear nerve. Here they combine to become the facial nerve. Facial canal path • The canal passes superior to the vestibule of the inner ear • At the medial aspect of the middle ear, it becomes wider and contains the geniculate ganglion. 3 branches: 1. 2. 3. Greater (superficial) petrosal nerve Nerve to stapedius Chorda tympani Stylomastoid foramen • Passes through the stylomastoid foramen (tympanic cavity anterior and mastoid antrum posteriorly) • Posterior auricular nerve and branch to posterior belly of digastric and stylohyoid muscle Face Enters parotid gland and divides into 5 branches: “The Zebra Buggered My Cat” • Temporal branch • Zygomatic branch • Buccal branch • Marginal mandibular branch • Cervical branch 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 30 31 The chorda tympani branch of the facial nerve passes forwards through itrs canaliculus into the middle ear, and crosses the medial aspect of the tympanic membrane. It then passes antero-inferiorly in the infratemporal fossa. It distributes taste fibres to the anterior two thirds of the tongue. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 31 32 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 32 33 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 33 Vagus Nerve 34 The vagus nerve has mixed functions and supplies the structures from the fourth and sixth pharyngeal arches. It also supplies the fore and midgut sections of the embryonic gut tube. It carries afferent fibres from these areas (viz; pharynx, larynx, oesophagus, stomach, lungs, heart and great vessels). The efferent fibres of the vagus are of two main types. The first are preganglionic parasympathetic fibres distributed to the parasympathetic ganglia that innervate smooth muscle of the innervated organs (such as gut). The second type of efferent fibres have direct skeletal muscle innervation, these are largely to the muscles of the larynx and pharynx. Origin and course The vagus arises from the lateral surface of the medulla oblongata by a series of rootlets. It is related to the glossopharyngeal nerve cranially and the accessory nerve caudally. It exits through the jugular foramen and is contained within its own dural sheath alongside the accessory nerve. In the neck it descends vertically in the carotid sheath where it is closely related to the internal and common carotid arteries. It leaves the neck and enters the mediastinum. On the right it passes anterior to the first part of the subclavian artery, on the left it lies in the interval between the common carotid and subclavian arteries. In the mediastinum both nerves pass postero-inferiorly and reach the posterior surface of the corresponding lung root. These then branch into both lungs. At the inferior end of the mediastinum these plexuses reunite to form the formal vagal trunks that pass through the oesophageal hiatus and into the abdomen. The anterior and posterior vagal trunks are formal nerve fibres these then splay out once again sending fibres over the stomach and posteriorly to the coeliac plexus. Branches pass to the liver, spleen and kidney. Communications and branches Communication Details Superior Located in jugular foramen ganglion Communicates with the superior cervical sympathetic ganglion, accessory nerve Two branches; meningeal and auricular (the latter may give rise to vagal stimulation following instrumentation of the external auditory meatus) Inferior Communicates with the superior cervical ganglion sympathetic ganglion, hypoglossal nerve and loop between first and second cervical ventral rami Two branches; pharyngeal (supplies pharyngeal muscles) and superior laryngeal nerve (inferomedially- deep to both carotid arteries) Branches in the neck (see before / parathyroid for pics) Branch Detail Superior and Arise at various points and descend into thorax inferior On the right these pass posterior to the subclavian cervical cardiac artery branches On the left the superior branch passes between the arch of the aorta and the trachea to connect with the deep cardiac plexus. The inferior branch descends with the vagus itself. Right recurrent Arises from vagus anterior to the first part of the laryngeal nerve subclavian artery, hooks under it, and ascends superomedially. It passes close to the common carotid and finally the inferior thyroid artery to insert into the larynx 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 34 Branches in the thorax (see before for pics) Branch Details Left recurrent Arises from the vagus on laryngeal the aortic arch. It hooks nerve around the inferior surface of the arch, posterior to the ligamentum arteriosum and passes upwards through the superior mediastinum and lower part of the neck. It lies in the groove between oesophagus and trachea (supplies both). It passes with the inferior thyroid artery and inserts into the larynx. Thoracic and There are extensive cardiac branches to both the heart branches and lung roots. These pass throughout both these viscera. The fibres reunite distally prior to passing into the abdomen. 35 Abdominal branches After entry into the abdominal cavity the nerves branch extensively. In previous years the extensive network of the distal branches (nerves of Laterjet) over the surface of the distal stomach were important for the operation of highly selective vagotomy. The use of modern PPI's has reduced the need for such highly selective procedures. Branches pass to the coeliac axis and alongside the vessels to supply the spleen, liver and kidney. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 35 36 Recurrent Laryngeal Nerve Branch of the vagus nerve Right Left • Arises anterior to the subclavian artery and • Arises left to the arch of the aorta ascends obliquely next to the trachea, behind • Winds below the aorta the common carotid artery • Ascends along the side of the trachea • It is either anterior or posterior to the inferior thyroid artery Then both • Pass in a groove between the trachea and oesophagus • Enters the larynx behind the articulation between the thyroid cartilage and cricoid • Distributed to larynx muscles Branches to • Cardiac plexus • Mucous membrane and muscular coat of the oesophagus and trachea Innervates • Intrinsic larynx muscles (excluding cricothyroid) Inferior vagal ganglion Superior laryngeal nerve Internal laryngeal nerve Right vagus ne External laryngeal nerve … Right recurrent laryngeal Left recurrent laryngeal Ligamentum arteriosum Left pulmonary artery 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 36 37 Lesser occipital nerve Ansa Cervicalis Superior root of Ansa Branch of C1 anterolateral to carotid sheath Cervicalis Derived from C2 and C3 roots, passes posterolateral to the internal jugular vein (may lie either deep or superficial to it) Transverse cervical n. Innervation Sternohyoid Sternothyroid Omohyoid The ansa cervicalis lies anterior to the carotid sheath in the anterior Δ. Inferior The nerve supply to the inferior strap muscles enters at their inferior aspect. root Therefore, when dividing these muscles to expose a large goitre, the muscles should be divided in their upper half. Superior root Inferior root Ansa cervicalis muscles: “GHost THought SOmeone STupid SHot Irene” GenioHyoid ThyroidHyoid Superior Omohyoid SternoThyroid SternoHyoid Inferior Omohyoid Nerve to geniohyoid (C1) Note: During a radical neck dissection, division of the Pretracheal fascia will expose the Ansa cervicalis. Thyrohyoid Superior root of Ansa cervicalis 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 37 Ear Anatomy 38 The ear is composed of three anatomically distinct regions. 1. External ear • Auricle is composed of elastic cartilage covered by skin. The lobule has no cartilage and contains fat and fibrous tissue. • External auditory meatus is approximately 2.5cm long. • Lateral third of the external auditory meatus is cartilaginous and the medial two thirds is bony. • The region is innervated by the greater auricular nerve. • The auriculotemporal branch of V 3 supplies most the of external auditory meatus and the lateral surface of the auricle. 2. Middle ear Space between the tympanic membrane and cochlea. The aditus leads to the mastoid air cells is the route through which middle ear infections may cause mastoiditis. Anteriorly the eustacian tube connects the middle ear to the naso pharynx. The tympanic membrane consists of: • Outer layer of stratified squamous epithelium. • Middle layer of fibrous tissue. • Inner layer of mucous membrane continuous with the middle ear. The tympanic membrane is approximately 1cm in diameter. The chorda tympani nerve passes on the medial side of the pars flaccida. The middle ear is innervated by the glossopharyngeal nerve and pain may radiate to the middle ear following tonsillectomy. Ossicles Malleus attaches to the tympanic membrane (the Umbo). Malleus articulates with the incus (synovial joint). Incus attaches to stapes (another synovial joint). 3. Internal ear • Cochlea, semicircular canals and vestibule • Organ of corti is the sense organ of hearing and is located on the inside of the cochlear duct on the basilar membrane. • Vestibule accommodates the utricule and the saccule. These structures contain endolymph and are surrounded by perilymph within the vestibule. • The semicircular canals lie at various angles to the petrous temporal bone. All share a common opening into the vestibule. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 38 Semicircular canals Semicircular duct 39 Facial nerve [VII] Vestibular nerve Vestibular ganglion Internal acoustic membrane Pharyngotympanic tube Prominence of facial canal Prominence of lat. Semicircular canal Promontory Tegmen tympani Tensor tympani muscle Aditus to mastoid antrum Round window Facial nerve 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA Internal carotid artery Chorda tympani Tympanic branch of glossopharyngeal nerve [IX] Internal jugular vein 39 40 Lacrimal System Lacrimal gland Consists of an orbital part and a palpebral part. They are continuous posterolaterally around the concave lateral edge of the levator palpebrae superioris muscle. The ducts of the lacrimal gland open into the superior fornix. Those from the orbital part penetrate the aponeurosis of levator palpebrae superioris to join those from the palpebral part. Therefore, excision of the palpebral part is functionally similar to excision of the entire gland. Blood supply Lacrimal branch of the ophthalmic artery (from ICA). Venous drainage is to the superior ophthalmic vein. Innervation The gland is innervated by the secretomotor parasympathetic fibres from the pterygopalatine ganglion which in turn may reach the gland via the zygomatic or lacrimal branches of the maxillary nerve or pass directly to the gland. The preganglionic fibres travel to the ganglion in the greater petrosal nerve (a branch of the facial nerve at the geniculate ganglion). Lacrimal gland Pterygoid canal Pterygopalatine ganglion ICA Nasolacrimal duct Descends from the lacrimal sac to open anteriorly in the inferior meatus of the nose. Nerve of pterygoid canal Sympathetic plexus Lacrimation reflex Occurs in response to conjunctival irritation (or emotional events). The conjunctiva will send signals via the ophthalmic nerve. These then pass to the superior salivary centre. The efferent signals pass via the greater petrosal nerve (parasympathetic preganglionic fibres) and the deep petrosal nerve which carries the post ganglionic sympathetic fibres. The parasympathetic fibres will relay in the pterygopalatine ganglion, the sympathetic fibres do not synapse. They in turn will relay to the lacrimal apparatus. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 40 Tonsil 41 Anatomy • Each palatine tonsil has two surfaces, a medial surface which projects into the pharynx and a lateral surface that is embedded in the wall of the pharynx. • They are usually 25mm tall by 15mm wide, although this varies according to age and may be almost completely atrophied in the elderly. • Their arterial supply is from the tonsillar artery, a branch of the facial artery. • Its veins pierce the constrictor muscle to join the external palatine or facial veins. The external palatine vein is immediately lateral to the tonsil, which may result in haemorrhage during tonsillectomy. • Lymphatic drainage is the jugulodigastric node and the deep cervical nodes. Tonsillitis • Usually bacterial (50%) - group A Streptococcus. Remainder viral. • May be complicated by development of abscess (quinsy). This may distort the uvula. • Indications for tonsillectomy include recurrent acute tonsillitis, suspected malignancy, enlargement causing sleep apnoea. • Dissection tonsillectomy is the preferred technique with haemorrhage being the commonest complication. Delayed otalgia may occur owing to irritation of the glossopharyngeal nerve. 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 41 Surface Anatomy 1A. ANATOMY (HEAD & NECK) – MRCS NOTES - REDA 42 42 43 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Abdominal wall ............................................................................................................................................... 2 External oblique muscle ................................................................................................................................. 3 Inguinal canal .................................................................................................................................................. 5 Scrotal and testicular anatomy ...................................................................................................................... 7 Colon anatomy ................................................................................................................................................ 8 Caecum .......................................................................................................................................................... 11 Transverse colon ........................................................................................................................................... 11 Left colon....................................................................................................................................................... 12 Rectum .......................................................................................................................................................... 12 Anal sphincter ............................................................................................................................................... 13 Spleen ............................................................................................................................................................ 14 Liver ............................................................................................................................................................... 15 Gallbladder .................................................................................................................................................... 17 Pancreas ........................................................................................................................................................ 18 Abdominal aorta ........................................................................................................................................... 19 Abdominal aortic branches .......................................................................................................................... 20 Coeliac axis .................................................................................................................................................... 21 Gastroduodenal artery ................................................................................................................................. 21 Inferior mesenteric artery ............................................................................................................................ 22 Renal anatomy .............................................................................................................................................. 23 Ureter ............................................................................................................................................................ 24 Adrenal gland anatomy ................................................................................................................................ 25 Prostate gland ............................................................................................................................................... 26 Epiploic (Omental) Foramen......................................................................................................................... 27 Inferior vena cava ......................................................................................................................................... 28 Diaphragm apertures .................................................................................................................................... 29 Uterus ............................................................................................................................................................ 30 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 1 44 Abdominal wall The 2 main muscles of the abdominal wall are the rectus abdominis (anterior) and the quadratus lumborum (posterior). The remaining abdominal wall consists of 3 muscular layers. Each muscle passes from the lateral aspect of the quadratus lumborum posteriorly to the lateral margin of the rectus sheath anteriorly. Each layer is muscular posterolaterally and aponeurotic anteriorly. Lineal alba Rectus abdominis Parietal peritoneum Lineal alba Rectus abdominis Transversus abdominis External Oblique Parietal peritoneum Transversus abdominis Transversus abdominis Internal oblique External oblique Muscles of abdominal wall • Lies most superficially • Originates from 5th to 12th ribs • Inserts into the anterior half of the outer aspect of the iliac crest, linea alba and pubic tubercle • More medially and superiorly to the arcuate line, the aponeurotic layer overlaps the rectus abdominis muscle • The lower border forms the inguinal ligament • The triangular expansion of the medial end of the inguinal ligament is the lacunar ligament. • Arises from the thoracolumbar fascia, the anterior 2/3 of the iliac crest and the lateral 2/3 of the inguinal ligament • The muscle sweeps upwards to insert into the cartilages of the lower 3 ribs • The lower fibres form an aponeurosis that runs from the tenth costal cartilage to the body of the pubis • At its lowermost aspect it joins the fibres of the aponeurosis of transversus abdominis to form the conjoint tendon. • Innermost muscle • Arises from the inner aspect of the costal cartilages of the lower 6 ribs, from the anterior 2/3 of the iliac crest and lateral 1/3 of the inguinal ligament • Its fibres run horizontally around the abdominal wall ending in an aponeurosis. The upper part runs posterior to the rectus abdominis. Lower down the fibres run anteriorly only. • The rectus abdominis lies medially; running from the pubic crest and symphysis to insert into the xiphoid process and 5th, 6th and 7th costal cartilages. The muscles lie in an aponeurosis as described above. • Nerve supply: anterior primary rami of T7-12 Surgical notes During abdominal surgery it is usually necessary to divide either the muscles or their aponeuroses. During a midline laparotomy it is desirable to divide the aponeurosis. This will leave the rectus sheath intact above the arcuate line and the muscles intact below it. Straying off the midline will often lead to damage to the rectus muscles, particularly below the arcuate line where they may often be in close proximity to each other. Quadratus lumborum Origin: Medial aspect of iliac crest and iliolumbar ligament Insertion: 12th rib Action: Pulls the rib cage inferiorly. Lateral flexion. Nerve supply: Anterior primary rami of T12 and L1-3 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 2 45 External oblique muscle External oblique forms the outermost muscle of the three muscles comprising the anterolateral aspect of the abdominal wall. Its aponeurosis comprises the anterior wall of the inguinal canal. Origin Insertion Nerve supply Actions Outer surfaces of the lowest eight ribs • Anterior two thirds of the outer lip of the iliac crest. • The remainder becomes the aponeurosis that fuses with the linea alba in the midline. Ventral rami of the lower six thoracic nerves Contains the abdominal viscera, may contract to raise intra-abdominal pressure. Moves trunk to one side. Transversus abdominis Muscle and aponeurosis Superficial fascia (Camper’s) Superficial fascia (Scarpa’s) Extraperitoneal fascia Parietal peritoneum Visceral peritoneum 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 3 46 Superficial fascia fatty layer (Camper’s fascia) Superficial fascia membranous layer (Scarpa’s fascia) Parietal peritoneum 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Extraperitoneal fascia 4 47 Inguinal canal • • • • Located above the inguinal ligament The inguinal canal is 4cm long The superficial ring is located anterior to the pubic tubercle The deep ring is located approximately 1.5-2cm above the half way point between the anterior superior iliac spine and the pubic tubercle Anterior superior iliac spine Superficial inguinal ring Boundaries of the inguinal canal “MALT” Transversalis fascia Inferior epigastric artery ASIS Inguinal ligament Deep inguinal ring Spermatic cord Inferior epigastric vessels Roof (Superior wall) “2 Muslces” Anterior wall “2 Aponeurosis” Floor (Inferior wall) “2 Ligaments” Posterior wall “2 Ts” Laterally Medially 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA • • • • • • • • • • • • • • Femoral a. and v. Deep ring Pubic symphysis Internal ablique Muscle Transversus abdominis Muscle External oblique Aponeurosis Internal oblique Aponeurosis External oblique aponeurosis Inguinal Ligament Lacunar Ligament Transversalis fascia Conjoint Tendon Internal ring Transversalis fascia Fibres of internal oblique External ring Conjoint tendon 5 48 Contents Male: Spermatic cord* and ilioinguinal nerve Female: Round ligament of uterus and ilioinguinal nerve ASIS *As it passes through the canal the spermatic cord has 3 coverings: • External spermatic fascia • Cremasteric fascia • Internal spermatic fascia External iliac a. External iliac v. Superficial inguinal ligament Lacunar ligament Right inguinal triangle - Internal view 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 6 49 Scrotal and testicular anatomy Spermatic cord Formed by the vas deferens and is covered by the following structures: Layer Origin External spermatic fascia External oblique aponeurosis Cremasteric fascia From the fascial coverings of internal oblique Internal spermatic fascia Transversalis fascia The tunica vaginalis is derived from peritoneum, it secretes the fluid that fills the hydrocele cavity. Contents of the cord Vas deferens Testicular artery Artery of vas deferens Cremasteric artery Pampiniform plexus Sympathetic nerve fibres Genital branch of the genitofemoral nerve Lymphatic vessels Transmits sperm and accessory gland secretions Branch of abdominal aorta supplies testis and epididymis Arises from inferior vesical artery Arises from inferior epigastric artery Venous plexus, drains into right or left testicular vein Lie on arteries, the parasympathetic fibres lie on the vas Supplies cremaster (→ cremasteric reflex) Drain to lumbar and para-aortic nodes Scrotum • Composed of skin and closely attached dartos fascia. • Arterial supply from the anterior and posterior scrotal arteries • Lymphatic drainage to the inguinal lymph nodes • Parietal layer of the tunica vaginalis is the innermost layer Layers of the scrotum “Some Damn Englishman Called It The Testes” • Skin • Dartos fascia and muscle • External spermatic fascia • Cremasteric fascia • Internal spermatic fascia • Tunica vaginalis • Testes Testes • • • • Genital branch of genitofemoral nerve Testicular a. and pampiniform plexus Cremasteric vessels Parietal peritoneum Extraperitoneal fascia Artery to ductus deferens Ext. oblique aponeurosis The testes are surrounded by the tunica vaginalis (closed peritoneal sac). The parietal layer of the tunica vaginalis adjacent to the internal spermatic fascia. The testicular arteries arise from the aorta immediately inferiorly to the renal arteries. The pampiniform plexus drains into the testicular veins, the left drains into the left renal vein and the right into the inferior vena cava. Lymphatic drainage is to the para-aortic nodes 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Internal oblique muscle Transversus abdominis Deep inguinal ring Conjoint tendon Superficial inguinal ring 7 Colon anatomy The colon commences with the caecum. This represents the most dilated segment of the human colon and its base (which is intraperitoneal) is marked by the convergence of teniae coli. At this point is located the vermiform appendix. The colon continues as the ascending colon, the posterior aspect of which is retroperitoneal. The line of demarcation between the intra and retro peritoneal right colon is visible as a white line, in the living, and forms the line of incision for colonic resections. 50 Right paracolic gutter Transverse colon The ascending colon becomes the transverse colon after passing the hepatic flexure. At this location the colon becomes wholly intra peritoneal once again. The superior aspect of the transverse colon is the point of attachment of the transverse colon to the greater omentum. This is an important anatomical site since division of these attachments permits entry into the lesser sac. Separation of the greater omentum from the transverse colon is a routine operative step in both gastric and colonic resections. At the left side of the abdomen the transverse colon passes to the left upper quadrant and makes an oblique inferior turn at the splenic flexure. Following this, the posterior aspect becomes retroperitoneal once again. At the level of approximately L4 the descending colon becomes wholly intraperitoneal and becomes the sigmoid colon. Whilst the sigmoid is wholly intraperitoneal there are usually attachments laterally between the sigmoid and the lateral pelvic sidewall. These small congenital adhesions are not formal anatomical attachments but frequently require division during surgical resections. Ascending colon Transverse colon At its distal end the sigmoid passes to the midline and at the region around the sacral promontary it becomes the upper rectum. This transition is visible macroscopically as the point where the teniae fuse. More distally the rectum passes through the peritoneum at the region of the peritoneal reflection and becomes extraperitoneal. Arterial supply Superior mesenteric artery and inferior mesenteric artery: linked by the marginal artery. Ascending colon: ileocolic and right colic arteries Transverse colon: middle colic artery Descending and sigmoid colon: inferior mesenteric artery Venous drainage From regional veins (that accompany arteries) to superior and inferior mesenteric vein The inferior mesenteric vein drains into the splenic vein, this point of union lies close to the duodenum and this surgical maneuver is a recognized cause of ileus. The middle colonic vein drains into the SMV, if avulsed during mobilisation then dramatic haemorrhage can occur and be difficult to control. Lymphatic drainage Initially along nodal chains that accompany supplying arteries, then para-aortic nodes. 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 8 51 Embryology Midgut: Second part of duodenum to 2/3 transverse colon Hindgut: Distal 1/3 transverse colon to anus Peritoneal location The right and left colon are part intraperitoneal and part extraperitoneal. The sigmoid and transverse colon are generally wholly intraperitoneal. This has implications for the sequelae of perforations, which will tend to result in generalised peritonitis in the wholly intra peritoneal segments. Colonic relations Region of colon Caecum/ right colon Hepatic flexure Splenic flexure Distal sigmoid/ upper rectum Rectum Relation Right ureter, gonadal vessels Gallbladder (medially) Spleen and tail of pancreas Left ureter Ureters, autonomic nerves, seminal vesicles, prostate, urethra (distally) Liver Stomach Short gastric veins Spleen Portal vein Left gastric vein Left gastro omental vein Splenic vein 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 9 Liver Xiphoid process Stomach Greater omentum 52 Inferior mesenteric artery Superior mesenteric artery Left colic artery Middle colic artery Arteria recta Right colic artery Sigmoid arteries Superior rectal artery 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 10 53 Caecum Location • Proximal right colon below the ileocaecal valve • Intraperitoneal Posterior relations • Psoas • Iliacus • Femoral nerve • Genitofemoral nerve • Gonadal vessels Anterior relations Greater omentum Arterial supply Ileocolic artery Lymphatic drainage Mesenteric nodes accompany the venous drainage The caecum is the most distensible part of the colon and in complete large bowel obstruction with a competent ileocaecal valve the most likely site of eventual perforation. Taenia coli Appendicular artery Positions of the appendix Transverse colon • • • • Subcaecal The right colon undergoes a sharp turn at the level of the hepatic flexure to become the transverse colon. At this point it also becomes intraperitoneal. It is connected to the inferior border of the pancreas by the transverse mesocolon. The greater omentum is attached to the superior aspect of the transverse colon from which it can easily be separated. The mesentery contains the middle colic artery and vein. The greater omentum remains attached to the transverse colon up to the splenic flexure. At this point the colon undergoes another sharp turn. Relations Superior Inferior Anterior Posterior Liver and gall-bladder, the greater curvature of the stomach, and the lower end of the spleen Small intestine Greater omentum From right to left with the descending portion of the duodenum, the head of the pancreas, convolutions of the jejunum and ileum, spleen 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 11 54 Left colon Position • As the left colon passes inferiorly its posterior aspect becomes extraperitoneal, and the ureter and gonadal vessels are close posterior relations that may become involved in disease processes • At a level of L3-4 (variable) the left colon becomes the sigmoid colon and wholly intraperitoneal once again • The sigmoid colon is a highly mobile structure and may even lie on the right side of the abdomen • It passes towards the midline, the taenia blend and this marks the transition between sigmoid colon and upper rectum Blood supply • Inferior mesenteric artery • However, the marginal artery (from the right colon) contributes, this contribution becomes clinically significant when the IMA is divided surgically (e.g. During AAA repair) Rectum The rectum is approximately 12 cm long. It is a capacitance organ. It has both intra and extraperitoneal components. The transition between the sigmoid colon is marked by the disappearance of the tenia coli.The extra peritoneal rectum is surrounded by mesorectal fat that also contains lymph nodes. This mesorectal fatty layer is removed surgically during rectal cancer surgery (Total Mesorectal Excision). The fascial layers that surround the rectum are important clinical landmarks, anteriorly lies the fascia of Denonvilliers. Posteriorly lies Waldeyers (presacral) fascia. Extra peritoneal rectum • Posterior upper third • Posterior and lateral middle third • Whole lower third Relations Anteriorly (Males) Anteriorly (Females) Posteriorly Laterally Left common iliac artery Left internal iliac artery Superior rectal artery Right common iliac artery Right internal iliac artery Rectovesical pouch Bladder Prostate Seminal vesicles Recto-uterine pouch (Douglas) Cervix Vaginal wall Sacrum Coccyx Middle sacral artery Levator ani Coccygeus Arterial supply Superior rectal a. (from inf. mesenteric a.) Middle rectal a. (from internal iliac a.) Inferior rectal a. (from internal pudendal a.) Venous drainage Superior rectal vein Lymphatic drainage • Mesorectal lymph nodes (superior to dentate line) • Inguinal nodes (inferior to dentate line) 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Inferior rectal artery Internal pudendal artery Middle rectal artery Arterial supply to the rectum and anal canal. Posterior view 12 Anal sphincter • • • 55 Internal anal sphincter composed of smooth muscle continuous with the circular muscle of the rectum. It surrounds the upper two- thirds of the anal canal and is supplied by sympathetic nerves. External anal sphincter is composed of striated muscle which surrounds the internal sphincter but extends more distally. The nerve supply of the external anal sphincter is from the inferior rectal branch of the pudendal nerve (S2 and S3) and the perineal branch of the S4 nerve roots. “S2, 3, 4 Keeps the poo off the floor” 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 13 56 Spleen Contents Relations The spleen is the largest lymphoid organ in the body. It is located in the left upper quadrant of the abdomen and its size can vary depending upon the amount of blood it contains. The typical adult spleen is 12.5cm long and 7.5cm wide. The normal spleen is not palpable. It is an intraperitoneal organ. The peritoneal attachments condense at the hilum where the vessels enter the spleen. The spleen is almost entirely covered by peritoneum, which adheres firmly to its capsule. Recesses of the greater sac separate it from the stomach and kidney. It develops from the upper dorsal mesogastrium, remaining connected to the posterior abdominal wall and stomach by two folds of peritoneum; the lienorenal ligament and gastrosplenic ligament. Its blood supply is from the splenic artery (derived from the coeliac axis) and the splenic vein (which is joined by the IMV and unites with the SMV) 1,3,5,7,9,11 (odd numbers up to 11) • Embryology: derived from mesenchymal tissue • Shape: clenched fist (influenced by the state of the colon and stomach) 1 inch thick, 3 inches wide, 5 inches long, • Position: below 9th-12th ribs weighs 7oz (150-200g), lies between the • Weight: 75-150g 9th and 11th ribs Superiorly Anteriorly Posteriorly Inferiorly Hilum Diaphragm Gastric impression Kidney Colon Tail of pancreas and splenic vessels (splenic artery divides here, branches pass to the white pulp transporting plasma) White pulp Immune function. Contains central trabecular artery. The germinal centres are supplied by arterioles called penicilliary radicles. Filters abnormal red blood cells. Red pulp Rib IX Stomach Spleen Function • Filtration of abnormal blood cells and foreign bodies such as bacteria. • Immunity: IgM. Production of properdin, and tuftsin which help target fungi and bacteria for phagocytosis. • Haematopoiesis: up to 5th month gestation or in haematological disorders. • Pooling: storage of 40% platelets. • Iron reutilization • Storage monocytes Disorders of the spleen Massive splenomegaly • Myelofibrosis • Chronic myeloid leukaemia • Visceral leishmaniasis (kala-azar) • Malaria • Gaucher's syndrome Other causes (as above plus) • Portal hypertension e.g. secondary to cirrhosis • Lymphoproliferative disease e.g. CLL, Hodgkin's • Haemolytic anaemia • Infection: hepatitis, glandular fever • Infective endocarditis • Sickle-cell*, thalassaemia • Rheumatoid arthritis (Felty's syndrome) *the majority of adult patients with sickle-cell will have an atrophied spleen due to repeated infarction Descending colon Greater omentum Small intestine Lesser omentum Stomach Gastrosplenic ligament Spleen Visceral peritoneum Splenorenal lig. Left kidney 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 14 57 Liver Structure of the liver Right lobe • Supplied by right hepatic artery • Contains Couinaud segments V to VIII (-/+Sg I) Left lobe • Supplied by the left hepatic artery • Contains Couinaud segments II to IV (+/- Sg1) Quadrate lobe • Part of the right lobe anatomically, functionally is part of the left • Couinaud segment IV • Porta hepatis lies behind • On the right lies the gallbladder fossa • On the left lies the fossa for the umbilical vein Caudate lobe • Supplied by both right and left hepatic arteries • Couinaud segment I • Lies behind the plane of the porta hepatis • Anterior and lateral to the inferior vena cava • Bile from the caudate lobe drains into both right and left hepatic ducts Between the liver lobules are portal canals which contain the portal triad: Hepatic Artery, Portal Vein, tributary of Bile Liver Diaphragm Duct. Relations of the liver Anterior Diaphragm Xiphoid process Postero inferiorly Oesophagus Stomach Duodenum Hepatic flexure of colon Right kidney Gallbladder Inferior vena cava Subphrenic recess Kidney Porta hepatis Hepatorenal recess Location Postero inferior surface, it joins nearly at right angles with the left sagittal fossa, and separates the caudate lobe behind from the quadrate lobe in front Transmits • Common hepatic duct • Hepatic artery • Portal vein • Sympathetic and parasympathetic nerve fibres • Lymphatic drainage of the liver (and nodes) Left triangle ligament Caudate lobe Suprarenal impression Falciform ligament Fundus of GB Body of GB Neck of GB Bare area Hepatic duct Quadrate lobe Fissure for ligamentum teres Right lobe Gastric impression Left lobe Renal impression Porta hepatis Rt lobe Cystic duct Neck of GB Left lobe Esophageal impression Body of GB Fundus of GB Porta hepatis Bile duct Quadrate lobe Portal vein Colic impression 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Hepatic artery Caudate lobe Fissure for ligamentum venosum 15 58 The cystic duct lies outside the porta hepatis and is an important landmark in laparoscopic cholecystectomy. The structures in the porta hepatis are: • Portal vein • Hepatic artery • Common hepatic duct These structures divide immediately after or within the porta hepatis to supply the functional left and right lobes of the liver. The porta hepatis is also surrounded by lymph nodes, that may enlarge to produce obstructive jaundice and parasympathetic nervous fibres that travel along vessels to enter the liver. Ligaments Falciform ligament Ligamentum teres Ligamentum venosum • 2 layer fold peritoneum from the umbilicus to anterior liver surface • Contains ligamentum teres (remnant umbilical vein) • On superior liver surface it splits into the coronary and left triangular ligaments Joins the left branch of the portal vein in the porta hepatis Remnant of ductus venosus Arterial supply • Hepatic artery Venous • Hepatic veins • Portal vein Nervous supply • Sympathetic and parasympathetic trunks of coeliac plexus 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 16 Gallbladder • • Fibromuscular sac with capacity of 50ml Columnar epithelium Relations of the gallbladder Anterior Liver Posterior • Covered by peritoneum • Transverse colon • 1st part of the duodenum Laterally Right lobe of liver Medially Quadrate lobe of liver 59 Right hepatic artery Common hepatic duct Gallbladder Left hepatic artery Hepatic artery proper Cystic artery Portal vein Gastroduodenal Common hepatic artery Cystic duct Bile duct Arterial supply Cystic artery (branch of Right hepatic artery) Splenic artery Right gastric artery Supraduodenal artery Venous drainage Directly to the liver Nerve supply Sympathetic- mid thoracic spinal cord, Parasympathetic- anterior vagal trunk Common bile duct Origin Confluence of cystic and common hepatic ducts Relations at • Medially - Hepatic artery origin • Posteriorly- Portal vein Relations • Duodenum – anteriorly distally • Pancreas - medially and laterally • Right renal vein - posteriorly Arterial Branches of hepatic artery and retroduodenal supply branches of gastroduodenal artery Hepatobiliary triangle Medially Common hepatic duct Inferiorly Cystic duct Superiorly Inferior edge of liver Contents Cystic artery Right hepatic duct Common hepatic duct Common hepatic duct Bile duct Bile duct Descending part of duodenum Main pancreatic duct 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 17 60 Pancreas The pancreas is a retroperitoneal organ and lies posterior to the stomach. It may be accessed surgically by dividing the peritoneal reflection that connects the greater omentum to the transverse colon. The pancreatic head sits in the curvature of the duodenum. Its tail lies close to the hilum of the spleen, a site of potential injury during splenectomy. Relations Posterior to the pancreas Head Inferior vena cava Common bile duct Right and left renal veins SMA and SMV Neck SMV, portal vein Body Left renal vein Crus of diaphragm Psoas muscle Adrenal gland Kidney Aorta Tail Left kidney Inferior vena cava Aorta Right kidney Anterior to the pancreas Head 1st part of the duodenum Pylorus Gastroduodenal artery SMA and SMV (uncinate process) Body Stomach Duodenojejunal flexure Tail Splenic hilum Superior to the pancreas Coeliac trunk and its branches common hepatic artery and splenic artery Grooves of the head of the pancreas 2nd and 3rd part of the duodenum Right kidney Jejunum Uncinate process Superior mesenteric vein Left gastro omental artery Superior mesenteric artery Splenic artery Left gastric artery Arterial supply • Head: pancreaticoduodenal artery • Rest: splenic artery Venous drainage • Head: superior mesenteric vein • Body and tail: splenic vein Ampulla of Vater • Merge of pancreatic duct and common bile duct • Is an important landmark, halfway along the second part of the duodenum, that marks the anatomical transition from foregut to midgut (also the site of transition between regions supplied by coeliac trunk and SMA). Inferior pancreaticoduodenal artery Anterior inferior pancreaticoduodenal artery Posterior inferior pancreaticoduodenal artery Superior mesenteric artery Blood supply of the pancreas. Posterior view 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA Posterior superior pancreaticoduodenal artery 18 61 Abdominal aorta Abdominal aortic topography Origin Termination Posterior relations Anterior relations Right lateral relations Left lateral relations T12 L4 L1-L4 Vertebral bodies Lesser omentum Liver Left renal vein Inferior mesenteric vein Third part of duodenum Pancreas Parietal peritoneum Peritoneal cavity Right crus of the diaphragm Cisterna chyli Azygos vein IVC (becomes posterior distally) 4th part of duodenum Duodenal-jejunal flexure Left sympathetic trunk Inferior phrenic artery Diaphragm Coeliac trunk Abdominal aorta anterior branches Middle suprarenal artery 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 19 62 Abdominal aortic branches 'Prostitutes Cause Sagging Swollen Red Testicles [in men] Living In Sin': Branches Level Inferior Phrenic T12 (Upper border) Coeliac T12 Superior mesenteric L1 Middle Suprarenal L1 Renal L1-L2 Testicular (in men) Gonadal L2 Lumbar L1-L4 Inferior mesenteric L3 Median Sacral L4 Common iliac L4 Paired Yes No No Yes Yes Yes Yes No No Yes Type Parietal Visceral Visceral Visceral Visceral Visceral Parietal Visceral Parietal Terminal Short gastric arteries Splenic artery Left gastric artery Left hepatic artery Spleen Common hepatic artery Right gastric artery Gastroduodenal artery Left gastro omental artery Superior duodenal artery Posterior superior pancreaticoduodenal artery Superior mesenteric artery Anterior superior pancreaticoduodenal artery Right gastro omental artery Inferior pancreaticoduodenal artery Transverse colon Marginal artery Aorta Marginal artery Middle colic artery Right colic artery Inferior mesenteric artery Marginal arteries Left colic artery Ileocolic artery Descending colon Ascending colon Sigmoid arteries Appendicular artery Appendix Superior rectal artery 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 20 Coeliac axis 63 The coeliac axis has three main branches. “Left Hand Side (LHS)” • Left gastric • Hepatic: Branches: Right Gastric, Gastroduodenal, Hepatic proper (right and left hepatic), Cystic (occasionally). • Splenic: Branches: Pancreatic, Short Gastric, Left Gastroepiploic It occasionally gives off one of the inferior phrenic arteries. Relations Anteriorly Right Left Inferiorly Lesser omentum Right coeliac ganglion and caudate process of liver Left coeliac ganglion and gastric cardia Upper border of pancreas and renal vein Gastroduodenal artery Supplies Pylorus, proximal part of the duodenum, and indirectly to the pancreatic head (via the anterior and posterior superior pancreaticoduodenal arteries) Path The gastroduodenal artery most commonly arises from the common hepatic artery of the coeliac trunk. It terminates by bifurcating into the right gastroepiploic artery and the superior pancreaticoduodenal artery (anterior and posterior) 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 21 Inferior mesenteric artery 64 The IMA is the main arterial supply of the embryonic hindgut and originates approximately 3-4 cm superior to the aortic bifurcation. From its aortic origin it passes immediately inferiorly across the anterior aspect of the aorta to eventually lie on its left hand side. At the level of the left common iliac artery it becomes the superior rectal artery. Branches The left colic artery arises from the IMA near its origin. More distally up to three sigmoid arteries will exit the IMA to supply the sigmoid colon. 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 22 65 Renal anatomy Each kidney is about 11cm long, 5cm wide and 3cm thick. They are located in a deep gutter alongside the projecting vertebral bodies, on the anterior surface of psoas major. In most cases the left kidney lies approximately 1.5cm higher than the right. The upper pole of both kidneys approximates with the 11th rib (beware pneumothorax during nephrectomy). On the left hand side the hilum is located at the L1 vertebral level and the right kidney at level L1-2. The lower border of the kidneys is usually alongside L3. Relations Right Kidney Left Kidney Posterior Quadratus lumborum, diaphragm, psoas major, Quadratus lumborum, diaphragm, psoas major, transversus abdominis transversus abdominis Anterior Hepatic flexure of colon Stomach, Pancreatic tail Superior Liver, adrenal gland Spleen, adrenal gland Rib XII Transversus abdominis Rib XII Structures related to the posterior surface of each kidney Transversus abdominis Fascial covering Each kidney and suprarenal gland is enclosed within a common layer of investing fascia, derived from the transversalis fascia. It is divided into anterior and posterior layers (Gerota’s fascia). Pyramid in renal medulla Structures at the renal hilum The renal vein lies most anteriorly, then renal artery (it is an end artery) and the ureter lies most posterior. Major calyx Renal artery Hilum Renal structure Kidneys are surrounded by an outer cortex and an inner medulla which usually contains between 6 and 10 pyramidal structures. The papilla marks the innermost apex of these. They terminate at the renal pelvis, into the ureter. Lying in a hollow within the kidney is the renal sinus. This contains: Renal sinus 1. Branches of the renal artery 2. Tributaries of the renal vein 3. Major and minor calyces's 4. Fat Renal vein Minor calyx Renal pelvis Ureter 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 23 66 Ureter • • • • • • • 25-35 cm long Muscular tube lined by transitional epithelium Surrounded by thick muscular coat. Becomes 3 muscular layers as it crosses the bony pelvis Retroperitoneal structure overlying transverse processes L2-L5 Lies anterior to bifurcation of iliac vessels Blood supply is segmental; renal artery, aortic branches, gonadal branches, common iliac and internal iliac. Lies beneath the uterine artery Abdominal aorta Right renal artery Left renal artery Left kidney 1st constriction Ureteropelvic junction 2nd constriction Entrance to bladder External iliac artery The ureter develops from the mesonephric duct. The mesonephric duct is associated with the metanephric duct that develops within the metanephrogenic blastema. This forms the site of the ureteric bud which branches off the mesonephric duct. 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 24 Adrenal gland anatomy Relationships Location Arterial supply Venous drainage Superomedially to the upper pole of each kidney Right adrenal Anteriorly: Hepato-renal pouch and bare area of the liver Inferiorly: Kidney Posteriorly: Diaphragm Medially: Vena Cava Superior adrenal arteries - from inferior phrenic artery Middle adrenal arteries - from aorta Inferior adrenal arteries - from renal arteries Right adrenal Via one central vein directly into the IVC 67 Left adrenal Anteriorly: Lesser sac and stomach Inferiorly: Pancreas and splenic vessels Posteromedially: Crus of the diaphragm Left adrenal Via one central vein into the left renal vein The right renal vein is very short and lies more inferiorly. 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 25 Prostate gland 68 The prostate gland is approximately the shape and size of a walnut and is located inferior to the bladder. It is separated from the rectum by Denonvilliers fascia and its blood supply is derived from the internal iliac vessels (via inferior vesical artery). The internal sphincter lies at the apex of the gland and may be damaged during prostatic surgery, affected individuals may complain of retrograde ejaculation. Arterial supply Venous drainage Lymphatic drainage Innervation Dimensions Lobes Zones Relations Anterior Posterior Lateral Inferior vesical artery (from internal iliac) Prostatic venous plexus (to paravertebral veins) Internal iliac nodes Inferior hypogastric plexus • Transverse diameter (4cm) • AP diameter (2cm) • Height (3cm) • Posterior lobe: posterior to urethra • Median lobe: posterior to urethra, in between ejaculatory ducts • Lateral lobes x 2 • Isthmus • Peripheral zone: subcapsular portion of posterior prostate. Most prostate cancers are here • Central zone • Transition zone • Stroma Pubic symphysis Prostatic venous plexus Denonvilliers (Rectoprostatic) fascia Rectum Ejaculatory ducts Venous plexus (lies on prostate) Levator ani (immediately below the puboprostatic ligaments) Denonvilliers (rectoprostatic) fascia separates the rectum from the prostate. Waldeyer’s (presacral) fascia separates the rectum from the sacrum 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 26 Epiploic (Omental) Foramen Also called foramen of Winslow The epiploic foramen has the following boundaries: Anteriorly (in the free edge of the lesser omentum) Posteriorly Inferiorly Superiorly 69 Bile duct to the right, portal vein behind and hepatic artery to the left. Inferior vena cava 1st part of the duodenum Caudate process of the liver During liver surgery or trauma, bleeding may be controlled using a Pringles maneuver, this involves placing a vascular clamp across the anterior aspect of the epiploic foramen. Thereby occluding: • Common bile duct • Hepatic artery • Portal vein 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 27 70 Inferior vena cava Path • • • • • • • • Origin: L5 Left and right common iliac veins merge to form the IVC. Passes right of midline Paired segmental lumbar veins drain into the IVC throughout its length The right gonadal vein empties directly into the cava and the left gonadal vein generally empties into the left renal vein. The next major veins are the renal veins and the hepatic veins Pierces the central tendon of diaphragm at T8 Right atrium Relations Anteriorly Posteriorly Level T8 L1 L2 L1-5 L5 Vein Hepatic vein Inferior phrenic vein Pierces diaphragm Suprarenal veins Renal vein Gonadal vein Lumbar veins Common iliac vein Formation of IVC Small bowel, first and third part of duodenum, head of pancreas, liver and bile duct, right common iliac artery, right gonadal artery Right renal artery, right psoas, right sympathetic chain, coeliac ganglion Mnemonic for the Inferior vena cava tributaries: “I Like To Rise So High” • Iliacs • Lumbar • Testicular • Renal • Suprarenal • Hepatic veins 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 28 Diaphragm apertures 71 Diaphragm aperture levels T8 (8 letters) = Vena cava T10 (10 letters) = Oesophagus T12 (12 letters) = Aortic hiatus 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 29 Uterus 72 The non-pregnant uterus resides entirely within the pelvis. The peritoneum invests the uterus and the structure is contained within the peritoneal cavity. The blood supply to the uterine body is via the uterine artery (branch of the internal iliac). The uterine artery passes from the inferior aspect of the uterus (lateral to the cervix) and runs alongside the uterus. It frequently anastomoses with the ovarian artery superiorly. Inferolaterally the ureter is a close relation and ureteric injuries are a recognised complication when pathology brings these structures into close proximity. The supports of the uterus include the central perineal tendon (perineal body) (the most important). The lateral cervical, round and uterosacral ligaments are condensations of the endopelvic fascia and provide additional structural support. 1B. ANATOMY (ABDOMEN) – MRCS NOTES - REDA 30 73 1C. ANATOMY (THORAX) – MRCS NOTES - REDA Mediastinum ................................................................................................................................................... 2 Sternal Angle ................................................................................................................................................... 3 Trachea ............................................................................................................................................................ 4 Oesophagus ..................................................................................................................................................... 5 Lung Anatomy ................................................................................................................................................. 6 Phrenic Nerve.................................................................................................................................................. 8 Thoracic Duct .................................................................................................................................................. 9 Heart Anatomy.............................................................................................................................................. 10 Superior Vena Cava....................................................................................................................................... 12 Thoracic Aorta ............................................................................................................................................... 13 Prosthetic Heart Valves On Chest X-Rays .................................................................................................... 13 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 1 Mediastinum 74 Region between the pulmonary cavities. It is covered by the mediastinal pleura. It does not contain the lungs. It extends from the thoracic inlet superiorly to the diaphragm inferiorly. Mediastinal regions • Superior mediastinum (between manubriosternal angle and T4/5) • Middle mediastinum • Posterior mediastinum • Anterior mediastinum Posterior Mediastinum Middle mediastinu m Anterior Superior mediastinum Region Contents • Superior vena cava • Brachiocephalic veins • Arch of aorta • Thoracic duct • Trachea • Oesophagus • Thymus • Vagus nerve • Left recurrent laryngeal nerve • Phrenic nerve • Thymic remnants • Lymph nodes • Fat • • • • • • • • • • • • Pericardium Heart Aortic root Arch of azygos vein Main bronchi Oesophagus Thoracic aorta Azygos vein Thoracic duct Vagus nerve Sympathetic nerve trunks Splanchnic nerves 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 2 Sternal Angle 75 Anatomical structures at the level of the manubrium and upper sternum Upper part of the • Left brachiocephalic vein manubrium • Brachiocephalic artery • Left common carotid • Left subclavian artery Lower part of the • Costal cartilages of the 2nd ribs manubrium / • Transition point between superior and inferior mediastinum manubrio-sternal • Arch of the aorta angle • Tracheal bifurcation • Union of the azygos vein and superior vena cava • The thoracic duct crosses to the midline 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 3 Trachea Trachea Location Arterial and venous supply Nerve 76 C6 vertebra to the upper border of T5 vertebra (bifurcation) Inferior thyroid arteries and the thyroid venous plexus. Branches of vagus, sympathetic and the recurrent nerves Relations in the neck Anterior • Isthmus of the thyroid gland (Superior • Inferior thyroid veins to • Arteria thyroidea ima (if exists) inferior) • Sternothyroid • Sternohyoid • Cervical fascia • Anastomosing branches between the anterior jugular veins Posterior Oesophagus. Laterally • Common carotid arteries • Right and left lobes of the thyroid gland • Inferior thyroid arteries • Recurrent laryngeal nerves Relations in the thorax Anterior • Lateral • Manubrium, the remains of the thymus, the aortic arch, left common carotid arteries, and the deep cardiac plexus In the superior mediastinum, on the right side is the pleura and right vagus; on its left side are the left recurrent nerve, the aortic arch, and the left common carotid and subclavian arteries. 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 4 77 Oesophagus • • 25cm long. Starts at C6 vertebra, pierces diaphragm at T10 and ends at T11 Squamous epithelium. The oesophagus has no serosal covering and hence holds sutures poorly. The Auerbach's and Meissner's nerve plexuses lie in between the longitudinal and circular muscle layers and submucosally. The sub mucosal location of the Meissner's nerve plexus facilitates its sensory role. Constrictions of the oesophagus Structure Distance from incisors Cricoid cartilage 15cm Arch of the Aorta 22.5cm Left principal bronchus 27cm Diaphragmatic hiatus 40cm Relations Anteriorly Posteriorly Left Right • • • • • • • • • • • Trachea to T4 Recurrent laryngeal nerve Left bronchus, Left atrium Diaphragm Thoracic duct to left at T5 Hemiazygos to the left T8 Descending aorta First 2 intercostal branches of aorta Thoracic duct Left subclavian artery Azygos vein Arterial, venous and lymphatic drainage of the oesophagus Artery Vein Lymphatics Upper third Inferior thyroid Inferior thyroid Deep cervical Mid third Aortic branches Azygos branches Mediastinal Lower third Left gastric Left gastric Gastric Muscularis externa Striated muscle Smooth & striated muscle Smooth muscle Nerve supply • Upper half is supplied by recurrent laryngeal nerve • Lower half by oesophageal plexus (vagus) Histology • Mucosa :Non-keratinized stratified squamous epithelium • Submucosa: glandular tissue • Muscularis externa (muscularis): composition varies. See table • Adventitia 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 5 Lung Anatomy 78 The right lung is composed of 3 lobes divided by the oblique and transverse fissures. The left lung has two lobes divided by the oblique fissure. The apex of both lungs is approximately 4cm superior to the sternocostal joint of the first rib. Immediately below this is a sulcus created by the subclavian artery. Peripheral contact points of the lung • Base: diaphragm • Costal surface: corresponds to the cavity of the chest • Mediastinal surface: Contacts the mediastinal pleura. Has the cardiac impression. Above and behind this concavity is a triangular depression named the hilum, where the structures which form the root of the lung enter and leave the viscus. These structures are invested by pleura, which, below the hilum and behind the pericardial impression, forms the pulmonary ligament Right lung • Above the hilum is the azygos vein; Superior to this is the groove for the superior vena cava and right innominate vein; behind this, and nearer the apex, is a furrow for the innominate artery. Behind the hilum and the attachment of the pulmonary ligament is a vertical groove for the oesophagus; In front and to the right of the lower part of the oesophageal groove is a deep concavity for the extrapericardial portion of the inferior vena cava. • The root of the right lung lies behind the superior vena cava and the right atrium, and below the azygos vein. • The right main bronchus is shorter, wider and more vertical than the left main bronchus and therefore the route taken by most foreign bodies. Left lung • Above the hilum is the furrow produced by the aortic arch, and then superiorly the groove accommodating the left subclavian artery; Behind the hilum and pulmonary ligament is a vertical groove produced by the descending aorta, and in front of this, near the base of the lung, is the lower part of the oesophagus. • The phrenic nerve lies anteriorly at this point (hilum of left lung). The vagus passes anteriorly and then arches backwards immediately superior to the root of the left bronchus, giving off the recurrent laryngeal nerve as it does so. • The root of the left lung passes under the aortic arch and in front of the descending aorta. Inferior borders of both lungs • 6th rib in mid clavicular line • 8th rib in mid axillary line • 10th rib posteriorly 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 6 The pleura runs two ribs lower than the corresponding lung level. Bronchopulmonary segments Segment number 1 2 3 4 5 6 7 8 9 10 Right lung Apical Posterior Anterior Lateral Medial Superior (apical) Medial basal Anterior basal Lateral basal Posterior basal 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 79 Left lung Apical Posterior Anterior Superior lingular Inferior lingular Superior (apical) Medial basal Anterior basal Lateral basal Posterior basal 7 Phrenic Nerve 80 Origin • C3,4,5 “C3, 4, 5 Keeps the diaphragm alive” Supplies • Diaphragm, sensation central diaphragm and pericardium Path • The phrenic nerve passes with the internal jugular vein across scalenus anterior. It passes deep to prevertebral fascia of deep cervical fascia. • Left: crosses anterior to the 1st part of the subclavian artery. • Right: Anterior to scalenus anterior and crosses anterior to the 2nd part of the subclavian artery. • On both sides, the phrenic nerve runs posterior to the subclavian vein and posterior to the internal thoracic artery as it enters the thorax. Right phrenic nerve • • • In the superior mediastinum: anterior to right vagus and laterally to superior vena cava Middle mediastinum: right of pericardium It passes over the right atrium to exit the diaphragm at T8 via vena cava hiatus. Left phrenic nerve • • • Passes lateral to the left subclavian artery, aortic arch and left ventricle Passes anterior to the root of the lung Pierces the diaphragm alone 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 8 Thoracic Duct • • • • • • 81 Continuation of the cisterna chyli in the abdomen. Enters the thorax at T12. Lies within the posterior and superior mediastinum. Lies posterior to the oesophagus for most of its intrathoracic course. Passes to the left at T5. Lymphatics draining the left side of the head and neck join the thoracic duct prior to its insertion into the left brachiocephalic vein. Lymphatics draining the right side of the head and neck drain via the subclavian and jugular trunks into the right lymphatic duct and thence into the mediastinal trunk and eventually the right brachiocephalic vein. Its location in the thorax makes it prone to injury during oesophageal surgery. Some surgeons administer cream to patients prior to oesophagectomy so that it is easier to identify the cut ends of the duct. 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 9 Heart Anatomy 82 The walls of each cardiac chamber comprise: • Epicardium • Myocardium • Endocardium Cardiac muscle is attached to the cardiac fibrous skeleton. Relations The heart and roots of the great vessels within the pericardial sac are related to the posterior aspect of the sternum, medial ends of the 3rd to 5th ribs on the left and their associated costal cartilages. The heart and pericardial sac are situated obliquely two thirds to the left and one third to the right of the median plane. The pulmonary valve lies at the level of the left third costal cartilage. The mitral valve lies at the level of the fourth costal cartilage. Coronary sinus This lies in the posterior part of the coronary groove and receives blood from the cardiac veins. The great cardiac vein lies at its left and the middle and small cardiac veins lie on its right. The smallest cardiac vein (anterior cardiac vein) drains into the right atrium directly. Aortic sinus Right coronary artery arises from the right aortic sinus, the left is derived from the left aortic sinus, which lies posteriorly. Features of the left ventricle as opposed to the right Structure Left Ventricle A-V Valve Mitral (double leaflet) Walls Twice as thick as right Trabeculae carnae Much thicker and more numerous Conus arteriosus Absent Right coronary artery The RCA supplies: • Right atrium • Diaphragmatic part of the right ventricle • Usually the posterior third of the interventricular septum • The sino atrial node (60% cases) • The atrio ventricular node (80% cases) Left coronary artery The LCA supplies: • Left atrium • Most of left ventricle • Part of the right ventricle • Anterior two thirds of the inter ventricular septum • The sino atrial node (remaining 40% cases) Innervation of the heart Autonomic nerve fibres from the superficial and deep cardiac plexus. These lie anterior to the bifurcation of the trachea, posterior to the ascending aorta and superior to the bifurcation of the pulmonary trunk. The parasympathetic supply to the heart is from presynaptic fibres of the vagus nerves. 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 10 Valves of the heart Mitral valve 2 cusps 1st heart sound 1 anterior cusp Attached to chordae tendinae 83 Aortic valve 3 cusps 2nd heart sound 2 anterior cusps No chordae Pulmonary valve 3 cusps 2nd heart sound 2 anterior cusps No chordae Tricuspid valve 3 cusps 1st heart sound 2 anterior cusps Attached to chordae tendinae ` 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 11 Superior Vena Cava 84 Drainage • Head and neck • Upper limbs • Thorax • Part of abdominal walls Formation • Subclavian and internal jugular veins unite to form the right and left brachiocephalic veins • These unite to form the SVC • Azygos vein joins the SVC before it enters the right atrium Relations Anterior Posteromedial Posterolateral Right lateral Left lateral Anterior margins of the right lung and pleura Trachea and right vagus nerve Posterior aspects of right lung and pleura Pulmonary hilum is posterior Right phrenic nerve and pleura Brachiocephalic artery and ascending aorta There are 4 collateral venous systems: • Azygos venous system • Internal mammary venous pathway • Long thoracic venous system with connections to the femoral and vertebral veins (2 pathways) Despite this, venous hypertension still occurs in SVC obstruction. Developmental variations Anomalies of the connection of the SVC are recognised. In some individuals a persistent left sided SVC drains into the right atrium via an enlarged orifice of the coronary sinus. More rarely the left sided vena cava may connect directly with the superior aspect of the left atrium, usually associated with an un-roofing of the coronary sinus. The commonest lesion of the IVC is for its abdominal course to be interrupted, with drainage achieved via the azygos venous system. This may occur in patients with left sided atrial isomerism. 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 12 Thoracic Aorta Origin Terminates Relations Branches 85 T4 T12 • Anteriorly: (from top to bottom) Root of the left lung, the pericardium, the oesophagus, and the diaphragm • Posteriorly: Vertebral column, Azygos vein • Right: Hemiazygos veins, Thoracic duct • Left: Left pleura and lung • Lateral segmental branches: Posterior intercostal arteries • Lateral visceral: Bronchial arteries supply bronchial walls and lung excluding the alveoli • Midline branches: Oesophageal arteries Prosthetic Heart Valves On Chest X-Rays The aortic and mitral valves are most commonly replaced and when a metallic valve is used, can be most readily identified on plain x-rays. The presence of cardiac disease (such as cardiomegaly) may affect the figures quoted here. Aortic Usually located medial to the 3rd interspace on the right. Mitral Usually located medial to the 4th interspace on the left. Tricuspid Usually located medial to the 5th interspace on the right. Please note that these are the sites at which an artificial valve may be located and are NOT the sites of auscultation. 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 13 86 1C. ANATOMY (THORAX) – MRCS NOTES - REDA 14 87 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Bones of the UL ............................................................................................................................................... 2 Muscles of the UL ............................................................................................................................................ 8 Muscles of the Shoulder ............................................................................................................................. 8 Muscles of the Arm and Forearm ............................................................................................................. 10 Extensor Retinaculum / Dorsal Wrist Compartments ............................................................................. 15 Neuroanatomic Relationships in the Forearm......................................................................................... 15 Muscles of the Hand and Wrist ................................................................................................................ 16 Hand .......................................................................................................................................................... 17 Arteries of the UL .......................................................................................................................................... 21 Axillary Artery ........................................................................................................................................... 21 Thoracoacromial Artery ............................................................................................................................ 21 Brachial Artery .......................................................................................................................................... 23 Ulnar Artery .............................................................................................................................................. 24 Radial Artery ............................................................................................................................................. 24 Veins of the UL .............................................................................................................................................. 25 Basilic Vein ................................................................................................................................................ 25 Nerves of the UL ............................................................................................................................................ 27 Brachial Plexus .......................................................................................................................................... 28 Summary of Upper Extremity Innervation............................................................................................... 29 Musculocutaneous Nerve ......................................................................................................................... 30 Median Nerve ........................................................................................................................................... 30 Ulnar Nerve ............................................................................................................................................... 31 Radial Nerve .............................................................................................................................................. 34 Joints of the UL .............................................................................................................................................. 36 Shoulder Joint ........................................................................................................................................... 36 Important Regions of the UL ........................................................................................................................ 38 Breast ........................................................................................................................................................ 38 Axilla .......................................................................................................................................................... 40 Cubital Fossa ............................................................................................................................................. 41 Surface Anatomy........................................................................................................................................... 42 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 1 Bones of the UL 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 88 2 89 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 3 90 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 4 91 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 5 92 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 6 93 Carpal bones Sally Likes To Play The Tiny Chrome Harmonica She Looks Too Pretty Try To Catch Her Scared Lovers Try Positions That They Can't Handle 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 7 94 Muscles of the UL Muscles of the Shoulder Muscle Origin Trapezius SP C7-T12 Latissimus dorsi SP T6-S5, ilium Humerus (ITG) Rhomboid major Rhomboid minor SP T2-T5 SP C7-T1 Transverse process C1-C4 Sternum, ribs, clavicle Ribs 3-5 Rib 1 Ribs 1-9 Lateral clavicle, scapula Scapula (medial border) Scapula (medial spine) Scapula (superior medial) Inferior scapula Humerus (medial ITG) Subscapularis Ventral scapula Humerus (lesser tuberosity) Supraspinatus Superior scapula Humerus (GT) Infraspinatus Dorsal scapula Humerus (GT) Teres minor Scapula (dorsolateral) Humerus (GT) Levator scapulae Pectoralis major Pectoralis minor Subclavius Serratus anterior Deltoid Teres major Insertion Clavicle, scapula (acromion, SP) Humerus (lateral ITG) Scapula (coracoid) Inferior clavicle Scapula (ventral medial) Humerus (deltoid tuberosity) Action Innervation Rotating scapula Cranial nerve XI Extending, adducting, internally rotating humerus Adducting scapula Adducting scapula Elevating, rotating scapula Adducting, internally rotating arm Protracting scapula Depressing clavicle Preventing winging Thoracodorsal nerve Dorsal scapular nerve Dorsal scapular nerve C3, C4 nerves Medial and lateral pectoral nerves Medial pectoral nerve Upper trunk nerves Long thoracic nerve Abducting arm Axillary nerve Adducting, internally rotating, extending arm Lower subscapular nerve Rotator cuff muscles Trapezius Internally rotating arm, providing anterior stability Abducting and externally rotating arm, providing stability Providing stability, externally rotating arm Providing stability, externally rotatjng arm Upper and lower subscapular nerves Suprascapular nerve Suprascapular nerve Axillary nerve Levator scapulae Rhomboid minor Latissimus dorsi 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 8 95 Supraspinatus Suprascapular notch (foramen) Cut edge of deltoid Surgical neck of humerus Medial lip of intertubercular sulcus Quadrangular space Teres major Triangular interval Long head of triceps brachii Deltoid tuberosity of humerus Cut edge of lateral head of triceps brachii 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 9 96 Muscles of the Arm and Forearm Muscle Origin Insertion Action Innervation Coracoid Coracoid (short head) Supraglenoid (long head) Anterior humerus Mid-humerus (medial) Radial tuberosity Flexion, adduction Supination, flexion Musculocutaneous Musculocutaneous Ulnar tuberosity (anterior) Flexing forearm Infraglenoid (long head) Posterior humerus (lateral head) Posterior humerus (medial head)* Olecranon Extending forearm (Elbow extension). The long head can adduct the humerus and and extend it from a flexed position Musculocutaneous, Radial Radial Muscles of the Arm Coracobrachialis Biceps brachii Brachialis Triceps brachii Blood supply by Profunda brachii artery The radial nerve and profunda brachii vessels lie between the lateral and medial heads Transverse humeral ligament Short head of biceps brachii muscle Coracobrachialis muscle Radial tuberosity 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 10 Muscle Origin 97 Insertion Action Innervation Pronating, flexing forearm Flexing wrist Flexing wrist Flexing wrist Flexing PIP joint Median nerve Superficial Flexors of the Forearm Pronator teres Medial epicondyle and coronoid Mid-lateral radius Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Medial epicondyle Medial epicondyle Medial epicondyle and posterior ulna Medial epicondyle, proximal anterior ulna and anterior radius 2nd & 3rd MC bases Palmar aponeurosis Pisiform Base of middle phalanges Humeral head of pronator teres Ulnar artery Separates the ulnar a. from the median n. Ulnar head of pronator teres Median nerve Median nerve Median nerve Ulnar nerve Median nerve Humeral head of flexor carpi ulnaris Ulnar head of flexor carpi ulnaris Flexor carpi ulnaris Pisohamate ligament Pisiform Pisometacarpal ligament Hook of hamate 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 11 Muscle Origin 98 Insertion Action Innervation Base of distal phalanges Base of distal phalanges Volar radius Flexing DIP joint Median–anterior interosseous/ulnar nerves Median–anterior interosseous nerve Deep Flexors of the Forearm Flexor digitorum profundus Flexor pollicis longus Pronator quadratus Anterior and medial ulna Anterior and lateral radius Distal ulna Flexing IP joint, thumb Pronating hand Median–anterior interosseous nerve Humero-ulnar head of flexor digitorum superficialis Interosseous membrane Flexor digitorum profundus Flexor digitorum superficialis Flexor digitorum superficialis tendon (cut) 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 12 Muscle Origin 99 Insertion Action Innervation Lateral distal radius Flexing forearm Radial nerve Second metacarpal base Third metacarpal base Proximal dorsal ulna Extensor aponeurosis Extending wrist Radial nerve Extending wrist Radial nerve Extending forearm Extending digits Small finger extensor expansion over P1 Fifth metacarpal base Extending small finger Extending/adducting hand Radial nerve Radial–posterior interosseous nerve Radial–posterior interosseous nerve Radial–posterior interosseous nerve Superficial Extensors of the Forearm Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Anconeus Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Lateral supracondylar humerus Lateral supracondylar humerus Lateral epicondyle of humerus Lateral epicondyle of humerus Lateral epicondyle of humerus Common extensor tendon Lateral epicondyle of humerus Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris Anterior View 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Posterior View 13 Muscle Origin 100 Insertion Action Innervation Lateral epicondyle of humerus, ulna Dorsal ulna/radius Dorsolateral radius Supinating forearm First metacarpal base Dorsal radius Thumb proximal phalanx base Thumb dorsal phalanx base Index finger extensor apparatus (ulnarly) Abducting/extending thumb Extending thumb MCP joint Extending thumb IP joint Extending index finger Radial–posterior interosseous nerve Radial–posterior interosseous nerve Radial–posterior interosseous nerve Radial–posterior interosseous nerve Radial–posterior interosseous nerve Deep Extensors of the Forearm Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis proprius Dorsolateral ulna Dorsolateral ulna Supinator (deep head) Supinator (superficial head) Abductor pollicis longus Extensor indicis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digiti minimi Abductor pollicis longus Extensor pollicis brevis Posterior View 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 14 Extensor Retinaculum / Dorsal Wrist Compartments 101 The extensor retinaculum is a thickening of the deep fascia that stretches across the back of the wrist and holds the long extensor tendons in position. Its attachments are: Structures superficial to the retinaculum • The pisiform and triquetral medially • Basilic vein • The end of the radius laterally • Dorsal cutaneous branch of the ulnar nerve • Cephalic vein Beneath the extensor retinaculum fibrous septa form six • Superficial branch of the radial nerve compartments that contain the extensor muscle tendons. Each compartment has its own synovial sheath. Compartment Contents I Abductor pollicis longus Extensor pollicis brevis II Extensor carpi radialis longus, Extensor carpi radialis brevis III Extensor pollicis longus IV V VI Extensor digitorum communis Extensor indicis proprius Extensor digiti minimi Extensor carpi ulnaris Pathologic Condition De Quervain’s tenosynovitis Extensor tendinitis (intersection syndrome) Rupture at Lister’s tubercle (after wrist fractures) Drummer’s tendinitis of the wrist Extensor tenosynovitis Rupture (rheumatoid arthritis: Vaughn-Jackson syndrome) Snapping at ulnar styloid Palmaris longus tendon Flexor retinaculum Median nerve Flexor carpi radialis tendon Flexor digitorum superficialis tendons Flexor pollicis longus tendon Extensor pollicis brevis tendon Cephalic vein Extensor carpi ulnaris Radial artery Extensor pollicis longus tendon Extensor digiti minimi tendon Extensor carpi radialis longus tendon Extensor digitorum tendons Extensor carpi radialis brevis tendon Extensor indicis tendon Neuroanatomic Relationships in the Forearm Nerve Radial Posterior interosseous Superficial radial Median Anterior interosseous Relationships Between brachialis and brachioradialis Splits supinator Between brachioradialis and extensor carpi radialis longus Medial to brachial artery at elbow Splits pronator teres and runs between flexor digitorum superficialis and flexor digitorum profundus Between flexor pollicis longus and flexor digitorum profundus Ulnar Between flexor carpi ulnaris and flexor digitorum profundus The radial artery passes between the lateral collateral ligament of the wrist joint and the tendons of the abductor pollicis longus and extensor pollicis brevis. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 15 102 Muscles of the Hand and Wrist Muscle Origin Insertion Action Innervation Scaphoid, trapezoid Base of proximal phalanx, radial side Thumb metacarpal Abducting thumb Median nerve Abducting, flexing, rotating (medially) Flexing MCP joint Median nerve Thenar Muscles Abductor pollicis brevis Opponens pollicis Flexor pollicis brevis Adductor pollicis Trapezium Trapezium, capitate Capitate, second and third metacarpals Base of proximal phalanx, radial side Base of proximal phalanx, ulnar side Adducting thumb Median, ulnar nerves Ulnar nerve Ulnar palm Retracting skin Ulnar nerve Base of proximal phalanx, ulnar side Base of proximal phalanx, ulnar side Small-finger metacarpal Abducting small finger Ulnar nerve Flexing MCP joint Ulnar nerve Abducting, flexing, rotating (laterally) Ulnar nerve Lateral bands (radial) Extending proximal interphalangeal joint Abducting, flexing MCP joint Adducting, flexing MCP joint Median, ulnar nerves Ulnar nerve Hypothenar Muscles Palmaris brevis Abductor digiti minimi Flexor digiti minimi brevis Opponens digiti minimi TCL, palmar aponeurosis Pisiform Hamate, TCL Hamate, TCL Intrinsic Muscles Lumbrical Dorsal interosseous Volar interosseous Flexor digitorum profundus Adjacent metacarpals Adjacent metacarpals Proximal phalanx base/extensor apparatus Proximal phalanx base/extensor apparatus Ulnar nerve Flexor digiti minimi brevis Three hypothenar muscles Adductor pollicis and first palmar interosseous insert into medial side of extensor hood Transverse head of adductor pollicis Opponens digiti minimi Radial artery Abductor digiti minimi (deep palmar arch) Sesamoid bone Oblique head of adductor pollicis Three thenar muscles Deep branch of ulnar artery and nerve Flexor carpi ulnaris Flexor pollicis brevis and abductor pollicis brevis insert into lateral side of extensor hood Opponens pollicis Recurrent branch of median nerve Abductor pollicis brevis Median nerve Flexor retinaculum 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 16 Hand Anatomy of the hand Bones Intrinsic Muscles Intrinsic muscles Thenar eminence Hypothenar eminence 103 • 8 Carpal bones • 5 Metacarpals • 14 phalanges 7 Interossei - Supplied by ulnar nerve • 3 palmar-adduct fingers • 4 dorsal- abduct fingers Lumbricals • Flex MCPJ and extend the IPJ. • Origin deep flexor tendon and insertion dorsal extensor hood mechanism. • Innervation: 1st and 2nd- median nerve, 3rd and 4th- deep branch of the ulnar nerve. • Abductor pollicis brevis • Opponens pollicis • Flexor pollicis brevis • Opponens digiti minimi • Flexor digiti minimi brevis • Abductor digiti minimi Fascia and compartments of the palm The fascia of the palm is continuous with the antebrachial fascia and the fascia of the dorsum of the hand. The palmar fascia is thin over the thenar and hypothenar eminences. In contrast, the central palmar fascia is relatively thick. The palmar aponeurosis covers the soft tissues and overlies the flexor tendons. The apex of the palmar aponeurosis is continuous with the flexor retinaculum and the palmaris longus tendon. Distally, it forms four longitudinal digital bands that attach to the bases of the proximal phalanges, blending with the fibrous digital sheaths. A medial fibrous septum extends deeply from the medial border of the palmar aponeurosis to the 5th metacarpal. Lying medial to this are the hypothenar muscles. In a similar fashion, a lateral fibrous septum extends deeply from the lateral border of the palmar aponeurosis to the 3rd metacarpal. The thenar compartment lies lateral to this area. Lying between the thenar and hypothenar compartments is the central compartment. It contains the flexor tendons and their sheaths, the lumbricals, the superficial palmar arterial arch and the digital vessels and nerves. The deepest muscular plane is the adductor compartment, which contains adductor pollicis. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 17 Short muscles of the hand These comprise the lumbricals and interossei. The four slender lumbrical muscles flex the fingers at the metacarpophalangeal joints and extend the interphalangeal joint. The four dorsal interossei are located between the metacarpals and the four palmar interossei lie on the palmar surface of the metacarpals in the interosseous compartment of the hand. 104 Long flexor tendons and sheaths in the hand The tendons of FDS and FDP enter the common flexor sheath deep to the flexor retinaculum. The tendons enter the central compartment of the hand and fan out to their respective digital synovial sheaths. Near the base of the proximal phalanx, the tendon of FDS splits to permit the passage of FDP. The FDP tendons are attached to the margins of the anterior aspect of the base of the distal phalanx. The fibrous digital sheaths contain the flexor tendons and their synovial sheaths. These extend from the heads of the metacarpals to the base of the distal phalanges. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 18 105 Interossei Origin and insertion Three palmar and four dorsal interossei occupy the spaces between the metacarpal bones. Each palmar interossei originates from the metacarpal of the digit on which it acts. Each dorsal interossei comes from the surface of the adjacent metacarpal on which it acts. As a result, the dorsal interossei are twice the size of the palmar ones. The interossei tendons, except the first palmar, pass to one or other side of the metacarpophalangeal joint posterior to the deep transverse metacarpal ligament. They become inserted into the base of the proximal phalanx and partly into the extensor hood Nerve supply They are all innervated by the ulnar nerve Actions Dorsal interossei abduct the fingers, palmar interossei adduct the fingers Clinical notes Along with the lumbricals the interossei flex the metacarpophalangeal joints and extend the proximal and distal interphalangeal joints. They are responsible for fine tuning these movements. When the interossei and lumbricals are paralysed the digits are pulled into hyperextension by extensor digitorum and a claw hand is seen. Dorsal interossei (palmar view) Palmar interossei (palmar view) Mnemonic “PAD & DAB” • Palmar interossei ADduct • Dorsal interossei ABduct 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 19 Anatomical snuffbox Posterior border (medially) Anterior border (laterally) Proximal border Distal border Floor Content 106 Tendon of extensor pollicis longus Tendons of extensor pollicis brevis and abductor pollicis longus Styloid process of the radius Apex of snuffbox triangle Trapezium and scaphoid Radial artery 1st dorsal interosseous muscle Anatomical snuffbox Extensor pollicis brevis tendon Extensor pollicis longus tendon Abductor pollicis longus tendon Cephalic vein Anatomical snuffbox Extensor pollicis longus tendon 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 20 107 Arteries of the UL Axillary Artery Part I II III Branch Sup. Thoracic a. Thoracoacromial a. Lateral thoracic a. Subscapular a. (largest br.) Anterior humeral circumflex a. Posterior humeral circumflex a. Course Medial to serratus anterior and pectoral muscles Four branches: deltoid, acromial, pectoralis, clavicular Descends to serratus anterior Two branches: thoracodorsal and circumflex scapular (triangular space) Blood supply to humeral head: arcuate artery lateral to bicipital groove Branch in the quadrangular space accompanying the axillary nerve Subclavius Pectoralis minor Superior thoracic artery Subscapularis Subscapular artery Anterior circumflex humeral artery Posterior circumflex humeral artery (quadrangular space) Latissimus dorsi Circumflex scapular branch (triangular space) Teres major Thoracodorsal artery Profunda brachii artery (triangular interval) 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 21 Thoracoacromial Artery 108 The thoracoacromial artery (acromiothoracic artery; thoracic axis) is a short trunk, which arises from the forepart of the axillary artery, its origin being generally overlapped by the upper edge of the Pectoralis minor. Projecting forward to the upper border of the Pectoralis minor, it pierces the coracoclavicular fascia and divides into four branches: pectoral, acromial, clavicular, and deltoid. Branch Pectoral branch Acromial branch Clavicular branch Deltoid branch Description Descends between the two Pectoral muscles, and is distributed to them and to the breast, anastomosing with the intercostal branches of the internal thoracic artery and with the lateral thoracic. Runs laterally over the coracoid process and under the Deltoid, to which it gives branches; it then pierces that muscle and ends on the acromion in an arterial network formed by branches from the suprascapular, thoracoacromial, and posterior humeral circumflex arteries. Runs upwards and medially to the sternoclavicular joint, supplying this articulation, and the Subclavius. Arising with the acromial, it crosses over the Pectoralis minor and passes in the same groove as the cephalic vein, between the Pectoralis major and Deltoid, and gives branches to both muscles. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 22 Brachial Artery 109 The brachial artery begins at the lower border of teres major as a continuation of the axillary artery. It terminates in the cubital fossa at the level of the neck of the radius by dividing into the radial and ulnar arteries. Relations • Posterior relations include the long head of triceps with the radial nerve and profunda vessels intervening. • Anteriorly it is overlapped by the medial border of biceps. • It is crossed by the median nerve in the middle of the arm. • In the cubital fossa it is separated from the median cubital vein by the bicipital aponeurosis. • The basilic vein is in contact at the most proximal aspect of the cubital fossa and lies medially. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 23 Ulnar Artery Path • • Starts: middle of antecubital fossa Passes obliquely downward, reaching the ulnar side of the forearm at a point about midway between the elbow and the wrist. It follows the ulnar border to the wrist, crossing over the flexor retinaculum. It then divides into the superficial and deep volar arches. 110 Humeral head of pronator teres Relations Deep to- Pronator teres, Flexor carpi radialis, Palmaris longus Lies on- Brachialis and Flexor digitorum profundus Superficial to the flexor retinaculum at the wrist Flexor carpi ulnaris (cut) The median nerve is in relation with the medial side of the artery for about 2.5 cm. And then crosses the vessel, being separated from it by the ulnar head of the Pronator teres The ulnar nerve lies medially to the lower two-thirds of the artery Common interosseous artery Posterior interosseous artery Flexor digitorum superficialis Anterior interosseous artery Branch • Anterior interosseous artery Radial Artery Perforating branches of anterior interosseous artery Brachioradialis tendon (cut) Flexor pollicis longus Interosseous membrane Flexor carpi radialis tendon (cut) Flexor carpi ulnaris tendon (cut) Superficial palmar arch of radial artery Ulnar nerve Deep palmar arch Superficial palmar arch 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 24 111 Veins of the UL Basilic Vein The basilic and cephalic veins both provide the main pathways of venous drainage for the arm and hand. It is continuous with the palmar venous arch distally and the axillary vein proximally. Path • • • • • • Originates on the medial side of the dorsal venous network of the hand, and passes up the forearm and arm. Most of its course is superficial. Near the region anterior to the cubital fossa the vein joins the cephalic vein. Midway up the humerus the basilic vein passes deep under the muscles. At the lower border of the teres major muscle, the anterior and posterior circumflex humeral veins feed into it. It is often joined by the medial brachial vein before draining into the axillary vein. Clavicle Clavipectoral triangle Biceps brachii Basilic vein Median cubital vein Cephalic vein 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 25 112 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 26 113 Nerves of the UL Musculocutaneous nerve • All muscles in anterior compartment of arm Median nerve • Most flexors in forearm • Thenar muscles in hand Radial nerve • All muscles in Ulnar nerve • Most intrinsic muscles in hand • Flexor carpi ulnaris and medial half of posterior compartment of arm and forearm flexor digitorum profundus in the forearm Axillary nerve • Superior lateral cutaneous nerve of arm Radial nerve • Inferior lateral Radial nerve • Inferior lateral cutaneous nerve of arm Musculocutaneus nerve • Inferior lateral cutaneous nerve of arm • Posterior cutaneous nerve of arm T2 • Posterior cutaneous nerve of forearm Musculocutaneus nerve • Inferior lateral cutaneous nerve of arm cutaneous nerve of arm Median nerve ANTERIOR 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Median nerve POSTERIOR 27 114 Brachial Plexus Origin Sections of the plexus Roots Trunks Divisions Cords Anterior rami of C5 to T1 • Roots, trunks, divisions, cords, branches • Mnemonic :Real Teenagers Drink Cold Beer • Located in the posterior triangle • Pass between scalenus anterior and medius • Located posterior to middle third of clavicle • Upper and middle trunks related superiorly to the subclavian artery • Lower trunk passes over 1st rib posterior to the subclavian artery Apex of axilla Related to axillary artery Lateral pectoral nerve Long thoracic nerve Intercostobrachial nerve (lateral cutaneous branch of T2) Superior subscapular nerve Thoracodorsal nerve Inferior subscapular nerve Median nerve 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Medial cutaneous nerve of the arm Medial cutaneous nerve of the forearm 28 115 Mnemonic branches off the posterior cord • Subscapular (upper and lower) • Thoracodorsal (Nerve to latissimus dorsi) • Axillary • Radial Summary of Upper Extremity Innervation Nerves Musculocutaneous (lateral cord) Axillary (posterior cord) Radial (posterior cord) Posterior interosseous Median (medial and lateral cord) Anterior interosseous Ulnar (medial cord) Muscles Innervated Coracobrachialis, biceps, brachialis Deltoid, teres minor Triceps, brachioradialis, extensor carpi radialis longus and brevis Supinator, extensor carpi ulnaris, extensor digitorum, extensor digiti minimi, abductor pollicis longus, extensor pollicis longus and brevis, extensor indicis proprius Pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, abductor pollicis brevis, supinator head of flexor pollicis brevis, opponens pollicis, first and second lumbrical muscles Flexor digitorum profundus (first and second), flexor pollicis longus, pronator quadratus Flexor carpi ulnaris, flexor digitorum profundus (third and fourth), palmaris brevis, abductor digiti minimi, opponens digiti minimi, flexor digiti minimi, third and fourth lumbrical muscles, interossei, adductor pollicis, deep head of flexor pollicis brevis 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 29 Musculocutaneous Nerve Path • • • • • 116 Branch of lateral cord of brachial plexus It penetrates the coracobrachialis muscle Passes obliquely between the biceps brachii and the brachialis to the lateral side of the arm Above the elbow it pierces the deep fascia lateral to the tendon of the biceps brachii Continues into the forearm as the lateral cutaneous nerve of the forearm Innervates • Coracobrachialis • Biceps brachii • Brachialis Median Nerve The median nerve is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8 and T1) cords of the brachial plexus; the medial root passes anterior to the third part of the axillary artery. The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery). It passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. It passes between the two heads of the pronator teres muscle, and runs on the deep surface of flexor digitorum superficialis (within its fascial sheath). Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to palmaris longus tendon. It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel. Branches Region Upper arm Forearm Distal forearm Hand (Motor) Hand (Sensory) Branch No branches, although the nerve commonly communicates with the musculocutaneous nerve Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorum superficialis Pronator quadratus Flexor pollicis longus Flexor digitorum profundus (only the radial half) Palmar cutaneous branch Motor supply (LOAF) • Lateral 2 lumbricals • Opponens pollicis • Abductor pollicis brevis • Flexor pollicis brevis • Over thumb and lateral 2 ½ fingers • On the palmar aspect this projects proximally, on the dorsal aspect only the distal regions are innervated with the radial nerve providing the more proximal cutaneous innervation. Patterns of damage: Damage at wrist • • • e.g. Carpal tunnel syndrome Paralysis and wasting of thenar eminence muscles and opponens pollicis (ape hand deformity) Sensory loss to palmar aspect of lateral (radial) 2 ½ fingers • • • Unable to pronate forearm Weak wrist flexion Ulnar deviation of wrist • • • Leaves just below the elbow Results in loss of pronation of forearm and weakness of long flexors of thumb and index finger Loss of pincer movement of the thumb and index finger. Damage at elbow, as above plus: Anterior interosseous nerve (branch of median nerve) 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 30 Ulnar Nerve Origin • C8, T1 Supplies (no muscles in the upper arm) • Flexor carpi ulnaris • Flexor digitorum profundus • Flexor digiti minimi • Abductor digiti minimi • Opponens digiti minimi • Adductor pollicis • Interossei muscle • Third and fourth lumbricals • Palmaris brevis Path • 117 Ulnar nerve: Mafia P Medial 2 lumbricals Adductor pollicis Flexor digitorum profundus/Flexor carpi ulnaris Interossei Abductor and Opponens and flexor digiti minimi (hypothenar eminence) Palmaris brevis Innervates all intrinsic muscles of the hand (EXCEPT 2: thenar muscles & first two lumbricals - supplied by median n.) Posteromedial aspect of upper arm to flexor compartment of forearm, then along the ulnar. Passes beneath the flexor carpi ulnaris muscle, then superficially through the flexor retinaculum into the palm of the hand. Branches Branch Muscular branch Palmar cutaneous branch (Arises near the middle of the forearm) Dorsal cutaneous branch Superficial branch Deep branch Effects of injury Damage at the wrist Damage at the elbow • • • • • Supplies Flexor carpi ulnaris Medial half of the flexor digitorum profundus Skin on the medial part of the palm Dorsal surface of the medial part of the hand Cutaneous fibres to the anterior surfaces of the medial one and one-half digits Hypothenar muscles All the interosseous muscles Third and fourth lumbricals Adductor pollicis Medial head of the flexor pollicis brevis Wasting and paralysis of intrinsic hand muscles (claw hand) Wasting and paralysis of hypothenar muscles Loss of sensation medial 1 and half fingers Radial deviation of the wrist Clawing less in 4th and 5th digits 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 31 118 Medial intermuscular septum Radial nerve Lateral cutaneous nerve of the forearm 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 32 119 Humeral head of pronator teres Flexor carpi ulnaris Ulnar head of pronator teres Flexor digitorum superficialis Anterior interosseous nerve Flexor digitorum profundus Brachioradialis tendon (cut) Flexor carpi radialis tendon (cut) Palmar branch (of median nerve) 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Flexor carpi ulnaris tendon (cut) Palmar branch (of ulnar nerve) 33 120 Radial Nerve Continuation of posterior cord of the brachial plexus (root values C5 to T1) Path • In the axilla: lies posterior to the axillary artery on subscapularis, latissimus dorsi and teres major. • Enters the arm between the brachial artery and the long head of triceps (medial to humerus). • Spirals around the posterior surface of the humerus in the groove for the radial nerve. • At the distal third of the lateral border of the humerus it then pierces the intermuscular septum and descends in front of the lateral epicondyle. • At the lateral epicondyle it lies deeply between brachialis and brachioradialis where it then divides into a superficial and deep terminal branch. • Deep branch crosses the supinator to become the posterior interosseous nerve. Regions innervated Motor (main • Triceps nerve) • Anconeus • Brachioradialis • Extensor carpi radialis Motor • Supinator (posterior • Extensor carpi ulnaris interosseous • Extensor digitorum branch) • Extensor indicis • Extensor digiti minimi • Extensor pollicis longus • Extensor pollicis brevis • Abductor pollicis longus Sensory The area of skin supplying the proximal phalanges on the dorsal aspect of the hand is supplied by the radial nerve (this does not apply to the little finger and part of the ring finger) Muscular innervation and effect of denervation Anatomical location Muscle affected Shoulder Long head of triceps Arm Triceps Forearm Supinator Brachioradialis Extensor carpi radialis longus and brevis 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Triangular interval Profunda brachii artery Radial nerve (in radial groove) Inferior lateral cutaneus nerve of the arm Posterior cutaneus nerve of forearm Effect of paralysis Minor effects on shoulder stability in abduction Loss of elbow extension Weakening of supination of prone hand and elbow flexion in mid prone position 34 121 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 35 122 Joints of the UL Shoulder Joint • • • Shallow synovial ball and socket type of joint. It is an inherently unstable joint, but is capable to a wide range of movement. Stability is provided by muscles of the rotator cuff that pass from the scapula to insert in the greater tuberosity (all except sub scapularis-lesser tuberosity). Glenoid labrum • Fibrocartilaginous rim attached to the free edge of the glenoid cavity • Tendon of the long head of biceps arises from within the joint from the supraglenoid tubercle, and is fused at this point to the labrum. • The long head of triceps attaches to the infraglenoid tubercle Fibrous capsule • Attaches to the scapula external to the glenoid labrum and to the labrum itself (postero-superiorly) • Attaches to the humerus at the level of the anatomical neck superiorly and the surgical neck inferiorly • Anteriorly the capsule is in contact with the tendon of subscapularis, superiorly with the supraspinatus tendon, and posteriorly with the tendons of infraspinatus and teres minor. All these blend with the capsule towards their insertion. • Two defects in the fibrous capsule; superiorly for the tendon of biceps. Anteriorly there is a defect beneath the subscapularis tendon. • The inferior extension of the capsule is closely related to the axillary nerve at the surgical neck and this nerve is at risk in anteroinferior dislocations. It also means that proximally sited osteomyelitis may progress to septic arthritis. Subacromial bursa (subdeltoid) Deltoid Long head of biceps brachii tendon Subtendinous bursa of subscapularis Fibrous membrane Long head of triceps Pectoralis major Short head of biceps brachii and coracobrachialis 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 36 Infraspinatus 123 Movements and muscles Flexion Anterior part of deltoid Pectoralis major Biceps Coracobrachialis Extension Posterior deltoid Teres major Latissimus dorsi Adduction Pectoralis major Latissimus dorsi Teres major Coracobrachialis Abduction Mid deltoid Supraspinatus Medial rotation Subscapularis Anterior deltoid Teres major Latissimus dorsi Lateral rotation Posterior deltoid Infraspinatus Teres minor Important anatomical relations Anteriorly Brachial plexus Axillary artery and vein Posterior Suprascapular nerve Suprascapular vessels Inferior Axillary nerve Circumflex humeral vessels Superior glenohumeral ligament Coracohumeral ligament Subtendinous bursa of subscapularis Coracohumeral ligament Middle glenohumeral ligament Synovial sheath Synovial membrane Long head of biceps brachii tendon Redundant capsule Redundant synovial membrane in adduction 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 37 Important Regions of the UL 124 Breast The breast itself lies on a layer of pectoral fascia and the following muscles: 1. Pectoralis major 2. Serratus anterior 3. External oblique Breast anatomy Nerve supply Arterial supply Venous drainage Lymphatic drainage Branches of intercostal nerves from T4-T6. • Internal mammary (thoracic) artery (60% of arterial supply) • External mammary artery (laterally) • Anterior intercostal arteries • Thoraco-acromial artery Superficial venous plexus to subclavian, axillary and intercostal veins. • 70% Axillary nodes • Internal mammary chain • Other lymphatic sites such as deep cervical and supraclavicular fossa (later in disease) 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 38 125 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 39 Axilla 126 Boundaries of the axilla Medially Chest wall and Serratus anterior Laterally Humeral head Floor Subscapularis Anterior aspect Lateral border of Pectoralis major Fascia Clavipectoral fascia Contents Long thoracic nerve (of Bell) Thoracodorsal nerve and thoracodorsal trunk Axillary vein Intercostobrachial nerves Lymph nodes Derived from C5-C7 and passes behind the brachial plexus to enter the axilla. It lies on the medial chest wall and supplies serratus anterior. Its location puts it at risk during axillary surgery and damage will lead to winging of the scapula. Innervate and vascularise latissimus dorsi. Lies at the apex of the axilla, it is the continuation of the basilic vein. Becomes the subclavian vein at the outer border of the first rib. Traverse the axillary lymph nodes and are often divided during axillary surgery. They provide cutaneous sensation to the axillary skin. The axilla is the main site of lymphatic drainage for the breast. 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 40 127 Cubital Fossa Triceps brachii Artery (brachial) Medial intermuscular septum Nerve (Median) Cubital fossa Line between lateral and medial epicondyles Bicipital aponeurosis Forearm flexors Radial artery Brachioradialis Forearm extensors Ulnar artery Ulnar nerve Radial nerve Median nerve Ulnar nerve Musculocutaneous nerve Medial cutaneous nerve of the forearm Pronator teres (humeral head) Brachioradialis (pulled back) Deep branch of radial nerve Lateral cutaneous nerve of the forearm Median cubital vein (separated from the brachial artery by the bicipital aponeurosis) Pronator teres (ulnar head) Ulnar artery Median nerve Supinator Radial artery Superficial branch of radial nerve 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA Cephalic vein Basilic vein 41 Surface Anatomy 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 128 42 129 1D. ANATOMY (UPPER LIMB) – MRCS NOTES - REDA 43 130 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Bones of the Pelvis and Lower Limbs ............................................................................................................. 2 Muscles of LL ................................................................................................................................................... 9 Gluteal Region ............................................................................................................................................. 9 Muscles Of The Pelvis And Hip ................................................................................................................. 10 Muscles Of The Thigh................................................................................................................................ 14 Muscles Of The Leg ................................................................................................................................... 17 Muscles Of The Ankle And Foot ............................................................................................................... 20 Greater Sciatic Foramen ........................................................................................................................... 22 Fascial Compartments Of The Leg ............................................................................................................ 23 Arteries of LL ................................................................................................................................................. 24 Anterior Tibial Artery ................................................................................................................................ 24 Posterior Tibial Artery .............................................................................................................................. 24 Femoral Artery .......................................................................................................................................... 26 Veins of LL ..................................................................................................................................................... 29 Saphenous Vein ........................................................................................................................................ 29 Nerves of LL ................................................................................................................................................... 30 Genitofemoral Nerve ................................................................................................................................ 32 Pudendal Nerve......................................................................................................................................... 33 Femoral Nerve........................................................................................................................................... 34 Obturator Nerve ....................................................................................................................................... 35 Sciatic Nerve.............................................................................................................................................. 36 Common Peroneal (Common Fibular) (Lat. Popliteal) Nerve.................................................................. 38 Deep Peroneal (Deep Fibular) (Ant. Tibial) Nerve ................................................................................... 39 Important Regions ........................................................................................................................................ 40 Femoral Triangle Anatomy ....................................................................................................................... 40 Femoral Canal ........................................................................................................................................... 41 Adductor Canal ......................................................................................................................................... 41 Popliteal Fossa .......................................................................................................................................... 42 Pudendal (Alcock’s) Canal......................................................................................................................... 42 Foot - Anatomy ......................................................................................................................................... 44 Joints of LL ..................................................................................................................................................... 47 Hip Joint..................................................................................................................................................... 47 Knee Joint .................................................................................................................................................. 48 Ankle Joint ................................................................................................................................................. 52 Surface Anatomy........................................................................................................................................... 54 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 1 Bones of the Pelvis and Lower Limbs 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 131 2 132 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 3 133 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 4 134 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 5 135 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 6 136 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 7 137 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 8 Muscles of LL 138 Gluteal Region Gluteal muscles • Gluteus maximus: inserts to gluteal tuberosity of the femur and iliotibial tract • Gluteus medius: attach to lateral greater trochanter • Gluteus minimis: attach to anterior greater trochanter • All extend and abduct the hip Deep lateral hip rotators • Piriformis • Gemelli • Obturator internus • Quadratus femoris Nerves Superior gluteal nerve (L5, S1) • Gluteus medius • Gluteus minimis • Tensor fascia lata Inferior gluteal nerve Gluteus maximus Damage to the superior gluteal nerve will result in the patient developing a Trendelenberg gait. Affected patients are unable to abduct the thigh at the hip joint. During the stance phase, the weakened abductor muscles allow the pelvis to tilt down on the opposite side. To compensate, the trunk lurches to the weakened side to attempt to maintain a level pelvis throughout the gait cycle. The pelvis sags on the opposite side of the lesioned superior gluteal nerve. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 9 139 Muscles Of The Pelvis And Hip Muscle Origin Insertion Nerve Segment Iliac fossa Transverse processes of L1-L5 Pectineal line of pubis Anterior inferior iliac spine, acetabular rim Anterior superior iliac spine Lesser trochanter Lesser trochanter Pectineal line of femur Patella and tibial tubercle Femoral Femoral Femoral Femoral L2-L4 (P) L2-L4 (P) L2-L4 (P) L2-L4 (P) Proximal medial tibia Femoral L2-L4 (P) Inferior pubic ramus/ischial tuberosity Inferior pubic ramus Anterior pubic ramus Inferior symphysis/pubic arch Linea aspera/adductor tubercle Linea aspera/pectineal line Linea aspera Proximal medial tibia Obturator (P) and sciatic (tibial) Obturator (P) Obturator (A) Obturator (A) L2-L4 (A) Flexors Iliacus Psoas Pectineus Rectus femoris Sartorius Adductors Adductor magnus Adductor brevis Adductor longus Gracilis Pes anserinus: Goose's Foot Combination of sartorius, gracilis and semitendinous tendons inserting into the anteromedial proximal tibia. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA L2-L4 (A) L2-L4 (A) L2-L4 (A) 10 140 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 11 Muscle 141 Origin Insertion Nerve Segment Gluteus maximus Ilium, posterior gluteal line Inferior gluteal L5-S2 (P) Piriformis Anterior sacrum/sciatic notch Piriformis S2 (P) Obturator externus Obturator internus Superior gemellus Ischiopubic rami/obturator Iliotibial band/gluteal sling (femur) Proximal greater trochanter Trochanteric fossa Obturator L2-L4 (A) Obturator internus L5-S2 (A) Obturator internus L5-S2 (A) Inferior gemellus Ischial tuberosity Quadratus femoris L5-S1 (A) Quadratus femoris Ischial tuberosity Medial greater trochanter Medial greater trochanter Medial greater trochanter Quadrate line of femur Quadratus femoris L5-S1 (A) Greater trochanter Superior gluteal L4-S1 (P) Anterior border of greater trochanter Iliotibial band Superior gluteal L4-S1 (P) Superior gluteal L4-S1 (P) External Rotators Ischiopubic rami/obturator membrane Outer ischial spine Abductors Gluteus medius Gluteus minimus Ilium between posterior and anterior gluteal lines Ilium between anterior and inferior gluteal lines Anterior iliac crest Tensor fasciae latae (tensor fasciae femoris) A, anterior; P, posterior. Mnemonic for muscle attachment on greater trochanter: POGO: • Piriformis • Obturator internus • Gemelli • Obturator externus 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 12 142 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 13 143 Muscles Of The Thigh Muscle Origin Insertion Innervation Iliotibial line/greater trochanter/lateral linea aspera Iliotibial line/medial linea aspera/supracondylar line Proximal anterior femoral shaft Lateral patella Femoral Medial patella Femoral Patella Femoral Muscles of the Anterior Thigh Vastus lateralis Vastus medialis Vastus intermedius 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 14 Muscle 144 Origin Insertion Innervation Medial ischial tuberosity Lateral linea aspera/lateral intermuscular septum Distal medial ischial tuberosity Proximal lateral ischial tuberosity Fibular head/lateral tibia Lateral tibial condyle Tibial Peroneal Anterior tibial crest Oblique popliteal ligament Posterior capsule Posterior/medial tibia Popliteus Medial meniscus Tibial Tibial Muscles of the Posterior Thigh Biceps femoris (long head) Biceps (short head) Semitendinosus Semimembranosus 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 15 145 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 16 146 Muscles Of The Leg Muscle Origin Anterior Compartment Tibialis anterior Lateral tibia Extensor hallucis longus Extensor digitorum longus Peroneus tertius Mid-fibula Tibial condyle/fibula Fibula and extensor digitorum longus tendon Lateral Compartment Peroneus longus Proximal fibula Peroneus brevis Distal fibula 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Insertion Action Innervation Medial cuneiform, first metatarsal Great toe, distal phalanx Toe, middle and distal phalanges Fifth metatarsal Dorsiflexing, inverting foot Dorsiflexing, extending toe Dorsiflexing, extending toe Everting, dorsiflexing, abducting foot Deep peroneal (L4) nerve Deep peroneal (L5) nerve Deep peroneal (L5) nerve Deep peroneal (S1) nerve Medial cuneiform, first metatarsal Tuberosity of fifth metatarsal Everting, plantar flexing, abducting foot Everting foot Superficial peroneal (S1) nerve Superficial peroneal (S1) nerve 17 Muscle Origin Superficial Posterior Compartment Gastrocnemius Posterior medial and lateral femoral condyles Soleus Fibula/tibia Plantaris Lateral femoral condyle 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 147 Insertion Action Innervation Calcaneus Plantar flexing foot Tibial (S1) nerve Calcaneus Calcaneus Plantar flexing foot Plantar flexing foot Tibial (S1) nerve Tibial (S1) nerve 18 Muscle Origin Deep Posterior Compartment Popliteus Lateral femoral condyle, fibular head Flexor hallucis Fibula longus Flexor digitorum Tibia longus Tibialis posterior Tibia, fibula, interosseous membrane 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 148 Insertion Action Innervation Proximal tibia Flexing, internally rotating knee Plantar flexing great toe Tibial (L5, S1) nerve Plantar flexing toes, foot Tibial (S1, S2) nerve Inverting/plantar flexing foot Tibial (L4, L5) nerve Great toe, distal phalanx Second to fifth toes, distal phalanges Navicular, medial cuneiform Tibial (S1) nerve 19 149 Muscles Of The Ankle And Foot Muscle Origin Insertion Action Innervation Superolateral calcaneus Base of proximal phalanges Extending Deep peroneal nerve Abductor hallucis Calcaneal tuberosity Abducting great toe Medial plantar nerve Flexor digitorum brevis Calcaneal tuberosity Flexing toes Medial plantar nerve Abductor digiti minimi Calcaneal tuberosity Base of great toe, proximal phalanx Distal phalanges of second to fifth toes Base of small toe Abducting small toe Lateral plantar nerve Quadratus plantae Medial and lateral calcaneus Flexor digitorum longus tendon Flexor digitorum longus tendon Extensor digitorum longus tendon Distal phalanges of digits Helping flex distal phalanges Lateral plantar nerve Medial and lateral plantar nerves Tibial nerve Dorsal Layer Extensor digitorum brevis First Plantar Layer Second Plantar Layer Lumbrical muscles Flexor digitorum longus and flexor hallucis longus Tibia/fibula 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Flexing metatarsophalangeal joint, extending interphalangeal joint Flexing toes, inverting foot 20 Muscle 150 Origin Insertion Action Innervation Cuboid/lateral cuneiform Oblique: second to fourth metatarsals Base of fifth metatarsal head Proximal phalanx of great toe Proximal phalanx of great toe (lateral) Proximal phalanx of small toe Flexing great toe Medial plantar nerve Adducting great toe Flexing small toe Lateral plantar nerve Third Plantar Layer Flexor hallucis brevis Adductor hallucis Flexor digiti minimi brevis Lateral plantar nerve Fourth Plantar Layer Dorsal interosseous Plantar interosseous (peroneus longus and tibialis posterior) Metatarsal Third to fifth metatarsals Fibula/tibia Dorsal extensors Abducting Proximal phalanges Adducting toes medially Medial Everting/inverting cuneiform/navicular foot Note: For abduction and adduction in the foot, the second toe serves as the reference. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Lateral plantar nerve Lateral plantar nerve Superficial peroneal/tibial nerve 21 Greater Sciatic Foramen Contents Nerves Vessels • • • • • • • • • 151 Sciatic Nerve Superior and Inferior Gluteal Nerves Pudendal Nerve Posterior Femoral Cutaneous Nerve Nerve to Quadratus Femoris Nerve to Obturator internus Superior Gluteal Artery and vein Inferior Gluteal Artery and vein Internal Pudendal Artery and vein Piriformis Is a landmark for identifying structures passing out of the sciatic notch • Above piriformis: Superior gluteal vessels • Below piriformis: Inferior gluteal vessels, sciatic nerve (10% pass through it, <1% above it), posterior cutaneous nerve of the thigh Greater sciatic foramen boundaries Anterolaterally Greater sciatic notch of the ilium Posteromedially Sacrotuberous ligament Inferior Sacrospinous ligament and the ischial spine Superior Anterior sacroiliac ligament Contents of the lesser sciatic foramen • Tendon of the obturator internus • Pudendal nerve • Internal pudendal artery and vein • Nerve to the obturator internus 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Structures passing between both foramina (Medial to lateral) PIN • Pudendal nerve • Internal pudendal artery • Nerve to obturator internus 22 152 Fascial Compartments Of The Leg Compartments of the thigh Formed by septae passing from the femur to the fascia lata. Compartment Nerve Muscles Anterior compartment Femoral • Iliacus • Tensor fasciae latae • Sartorius • Quadriceps femoris Medial compartment Obturator • Adductor longus/magnus/brevis • Gracilis • Obturator externus Posterior compartment (2 Sciatic • Semimembranosus layers) • Semitendinosus • Biceps femoris Blood supply Femoral artery Profunda femoris artery and obturator artery Branches of Profunda femoris artery Compartments of the lower leg Separated by the interosseous membrane (anterior and posterior compartments), anterior fascial septum (separate anterior and lateral compartments) and posterior fascial septum (separate lateral and posterior compartments) Compartment Nerve Muscles Blood supply Anterior Deep peroneal Anterior tibial • Tibialis anterior compartment nerve artery • Extensor digitorum longus • Extensor hallucis longus • Peroneus tertius Posterior Tibial Posterior tibial • Muscles: deep and superficial compartments compartment (separated by deep transverse fascia) • Deep: Flexor hallucis longus, Flexor digitalis longus, Tibialis posterior, Popliteus • Superficial: Gastrocnemius, Soleus, Plantaris Lateral Superficial Peroneal artery • Peroneus longus/brevis compartment peroneal 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 23 Arteries of LL 153 Anterior Tibial Artery • • • • • Begins opposite the distal border of popliteus Terminates in front of the ankle, continuing as the dorsalis pedis artery As it descends it lies on the interosseous membrane, distal part of the tibia and front of the ankle joint Passes between the tendons of extensor digitorum and extensor hallucis longus distally It is related to the deep peroneal nerve, it lies anterior to the middle third of the vessel and lateral to it in the lower third • • • • Larger terminal branch of the popliteal artery Terminates by dividing into the medial and lateral plantar arteries Accompanied by two veins throughout its length Position of the artery corresponds to a line drawn from the lower angle of the popliteal fossa, at the level of the neck of the fibula, to a point midway between the medial malleolus and the most prominent part of the heel Posterior Tibial Artery Relations of the posterior tibial artery (Proximal to distal) Anteriorly Tibialis posterior Flexor digitorum longus Posterior surface of tibia and ankle joint Posterior Tibial nerve 2.5 cm distal to its origin Fascia overlying the deep muscular layer Proximal part covered by gastrocnemius and soleus Distal part covered by skin and fascia 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 24 154 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 25 155 External iliac artery Superficial epigastric artery Sartorius muscle Superficial external iliac artery Femoral artery Midway between ASIS and pubic symphysis inferior to inguinal ligament Superficial external pudendal artery Deep external pudendal artery Deep artery of the thigh Artery passing through adductor hiatus and becoming popliteal artery Femoral Artery Beginning: Behind inguinal lig. At the mid inguinal point as a continuation of the external iliac artery. Path: • Its upper ½ lies superficial in the femoral triangle • Its lower ½ lies deep in the subsartorial canal Termination: At the junction of upper 2/3 and lower 1/3 of the thigh by passing through the opening in adductor magnus m. to become the popliteal artery. Branches: • • • Superficial branches Superficial epigastric artery Superficial external pudendal artery Superficial circumflex iliac artery 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA • • • Deep branches Profunda femoris artery Deep external pudendal artery Descending genicular artery 26 156 Deep artery of thigh. A. Anterior view. B. Posterior view. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 27 157 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 28 Veins of LL 158 Saphenous Vein Long saphenous vein This vein may be harvested for bypass surgery, or removed as treatment for varicose veins with saphenofemoral junction incompetence. • Originates at the 1st digit where the dorsal vein merges with the dorsal venous arch of the foot • Passes anterior to the medial malleolus and runs up the medial side of the leg • At the knee, it runs over the posterior border of the medial epicondyle of the femur bone • Then passes laterally to lie on the anterior surface of the thigh before entering an opening in the fascia lata called the saphenous opening • It joins with the femoral vein in the region of the femoral triangle at the saphenofemoral junction Tributaries • Medial marginal • Superficial epigastric • Superficial iliac circumflex • Superficial external pudendal veins Short saphenous vein • Originates at the 5th digit where the dorsal vein merges with the dorsal venous arch of the foot, which attaches to the great saphenous vein. • It passes around the lateral aspect of the foot (inferior and posterior to the lateral malleolus) and runs along the posterior aspect of the leg (with the sural nerve) • Passes between the heads of the gastrocnemius muscle, and drains into the popliteal vein, approximately at or above the level of the knee joint. The sural nerve is related to the short saphenous vein. The saphenous nerve is related to the long saphenous vein below the knee and for this reason full length stripping of the vein is no longer advocated. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 29 Nerves of LL 159 Lumbosacral Plexus Divisions and Innervations Nerve Level Muscles Innervated Anterior Division Tibia L4-S3 Quadratus femoris Obturator internus Pudendal L4-S1 L5-S2 S2-S4 Coccygeus Levator ani S4 S3-S4 Semimembranosus, semitendinosusbiceps brachii (long head), adductor magnus, superior gemellus, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus, flexor hallucis longus Quadratus femoris, inferior gemellus Obturatorius internus, superior gemellus Sensory: perineal Motor: bulbocavernosus, urethra, urogenital Coccygeus Levator ani Posterior Division Peroneal L4-S2 Superior gluteal Inferior gluteal Piriformis Posterior femoral cutaneous L4-S1 L5-S2 S2 S1-S3 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Biceps (short head), tibialis anterior, extensor digitorum longus, peroneus tertius, extensor hallucis longus Peroneus longus and brevis, extensor hallucis brevis, extensor digitorum brevis Gluteus medius and minimus, tensor fascia lata Gluteus maximus Piriformis Sensory: posterior thigh 30 160 Important Neurologic Features of Lower Extremity Joint Function Neurologic Level Hip Flexion T12-L3 Extension S1 Adduction L2-L4 Abduction L5 Knee Flexion L5, S1 Extension L2-L4 Ankle Dorsiflexion L4, L5 Plantar flexion S1, S2 Inversion L4 Eversion S1 Extensor hallucis longus is derived from L5 and loss of EHL function is a useful test to determine whether this level is involved. Innervation of the Thigh Nerve Components Femoral L2-L4 Obturator L2-L4 Sciatic L4-S3 Muscles Innervated Iliacus, psoas major (lower part), sartorius, pectineus, quadriceps, articularis genus Obturator externus, hip adductors (brevis, longus, magnus), gracilis Peroneal division: short head of biceps femoris Tibial division: hamstrings (semitendinosus, semimembranosus), part of adductor magnus, long head of biceps femoris Innervation of Lower Extremity Nerves Muscles Innervated Femoral Iliacus, psoas, quadriceps femoris (rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis) Obturator Adductor brevis, adductor longus, adductor magnus (along with tibial nerve), gracilis Superior gluteal Gluteus medius, gluteus minimus, tensor fascia lata Inferior gluteal Gluteus maximus Sciatic Semitendinosus, semimembranosus, biceps femoris (long head [tibial division] and short head [peroneal division]), adductor magnus (with obturator nerve) Tibial Gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, flexor hallucis longus, medial and lateral plantar nerves Deep peroneal Tibialis anterior, extensor digitorum longus, extensor hallucis longus, peroneus tertius, extensor digitorum brevis Superficial peroneal Peroneus longus, peroneus brevis Innervation of the Ankle and Foot Nerves Muscles Innervated Medial plantar Flexor hallucis brevis, abductor hallucis, flexor digitorum brevis, first lumbrical muscle Lateral plantar Pronator quadratus, abductor digiti minimi, flexor digiti minimi, adductor hallucis, interossei, second to fourth lumbrical muscles 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 31 161 Genitofemoral Nerve Supplies Small area of the upper medial thigh. Path • Arises from the first and second lumbar nerves. • Passes obliquely through psoas major, and emerges from its medial border opposite the fibrocartilage between the third and fourth lumbar vertebrae. • It then descends on the surface of psoas major, under cover of the peritoneum • Divides into genital and femoral branches. • The genital branch passes through the inguinal canal, within the spermatic cord, to supply the skin and fascia of the scrotum. The femoral branch enters the thigh posterior to the inguinal ligament, lateral to the femoral artery. It supplies an area of skin and fascia over the femoral triangle. • It may be injured during abdominal or pelvic surgery, or during inguinal hernia repairs. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 32 Pudendal Nerve 162 The pudendal nerve arises from nerve roots S2, S3 and S4 and exits the pelvis through the greater sciatic foramen. It reenters the perineum through the lesser sciatic foramen. It travels inferior to give innervation to the anal sphincters and external urethral sphincter. It also provides cutaneous innervation to the region of perineum surrounding the anus and posterior vulva. Traction and compression of the pudendal nerve by the foetus in late pregnancy may result in late onset pudendal neuropathy which may be part of the process involved in the development of faecal incontinence. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 33 Femoral Nerve Root values Innervates Branches 163 L2, 3, 4 • Pectineus • Sartorius • Quadriceps femoris • Vastus lateralis/medialis/intermedius • Medial cutaneous nerve of thigh • Saphenous nerve • Intermediate cutaneous nerve of thigh Path Penetrates psoas major and exits the pelvis by passing under the inguinal ligament to enter the femoral triangle, lateral to the femoral artery and vein. Mnemonic for femoral nerve supply (don't) M I S V Q Scan for PE M edial cutaneous nerve of the thigh I ntermediate cutaneous nerve of the thigh S aphenous nerve V astus Q uadriceps femoris S artorius PE ectineus 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 34 Obturator Nerve 164 The obturator nerve arises from L2, L3 and L4 by branches from the ventral divisions of each of these nerve roots. L3 forms the main contribution and the second lumbar branch is occasionally absent. These branches unite in the substance of psoas major, descending vertically in its posterior part to emerge from its medial border at the lateral margin of the sacrum. It then crosses the sacroiliac joint to enter the lesser pelvis, it descends on obturator internus to enter the obturator groove. In the lesser pelvis the nerve lies lateral to the internal iliac vessels and ureter, and is joined by the obturator vessels lateral to the ovary or ductus deferens. Supplies • Medial compartment of thigh • Muscles supplied: external obturator, adductor longus, adductor brevis, adductor magnus (not the lower part-sciatic nerve), gracilis • The cutaneous branch is often absent. When present, it passes between gracilis and adductor longus near the middle part of the thigh, and supplies the skin and fascia of the distal two thirds of the medial aspect. Obturator canal • Connects the pelvis and thigh: contains the obturator artery, vein, nerve which divides into anterior and posterior branches. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 35 165 Sciatic Nerve The sciatic nerve is formed from the sacral plexus and is the largest nerve in the body. It is the continuation of the main part of the plexus arising from ventral rami of L4 to S3. These rami converge at the inferior border of piriformis to form the nerve itself. It passes through the inferior part of the greater sciatic foramen and emerges beneath piriformis. Medially, lie the inferior gluteal nerve and vessels and the pudendal nerve and vessels. It runs inferolaterally under the cover of gluteus maximus midway between the greater trochanter and ischial tuberosity. It receives its blood supply from the inferior gluteal artery. The nerve provides cutaneous sensation to the skin of the foot and the leg. It also innervates the posterior thigh muscles and the lower leg and foot muscles. The nerve splits into the tibial and common peroneal nerves approximately half way down the posterior thigh. The tibial nerve supplies the flexor muscles and the common peroneal nerve supplies the extensor muscles and the abductor muscles. Summary points Origin Articular Branches Muscular branches in upper leg Cutaneous sensation Terminates • • Spinal nerves L4 - S3 Hip joint • Semitendinosus • Semimembranosus • Biceps femoris • Part of adductor magnus • Posterior aspect of thigh (via cutaneous nerves) • Gluteal region • Entire lower leg (except the medial aspect) At the upper part of the popliteal fossa by dividing into the tibial and peroneal nerves Major nerves of the LL (colors indicate regions of motor innervation) The nerve to the short head of the biceps femoris comes from the common peroneal part of the sciatic and the other muscular branches arise from the tibial portion. The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis (which is innervated by the common peroneal nerve). Sciatic nerve Medial popliteal nerve Lateral popliteal nerve (Tibial nerve) (Common fibular/peroneal nerve) Posterior tibial nerve Medial planter nerve Superficial peroneal/fibular nerve Deep peroneal/fibular nerve (musculocutaneous nerve) (Anterior tibial nerve) Lateral planter nerve 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 36 166 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 37 Common Peroneal (Common Fibular) (Lat. Popliteal) Nerve 167 Derived from the dorsal divisions of the sacral plexus (L4, L5, S1 and S2). This nerve supplies the skin and fascia of the anterolateral surface of the leg and the dorsum of the foot. It also innervates the muscles of the anterior and peroneal compartments of the leg, extensor digitorum brevis as well as the knee, ankle and foot joints. It is laterally placed within the sciatic nerve. From the bifurcation of the sciatic nerve it passes inferolaterally in the lateral and proximal part of the popliteal fossa, under the cover of biceps femoris and its tendon. To reach the posterior aspect of the fibular head. It ends by dividing into the deep and superficial peroneal nerves at the point where it winds around the lateral surface of the neck of the fibula in the body of peroneus longus, approximately 2cm distal to the apex of the head of the fibula. It is palpable posterior to the head of the fibula. Branches In the thigh In the popliteal fossa Neck of fibula Nerve to the short head of biceps Articular branch (knee) Lateral cutaneous nerve of the calf Superficial and deep peroneal nerves 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 38 Deep Peroneal (Deep Fibular) (Ant. Tibial) Nerve Origin Nerve root values Course and relation Terminates Muscles innervated Cutaneous innervation Actions 168 From the common peroneal nerve, at the lateral aspect of the fibula, deep to peroneus longus L4, L5, S1, S2 • Pierces the anterior intermuscular septum to enter the anterior compartment of the lower leg • Passes anteriorly down to the ankle joint, midway between the two malleoli In the dorsum of the foot • Tibialis anterior • Extensor hallucis longus • Extensor digitorum longus • Peroneus tertius • Extensor digitorum brevis Web space of the first and second toes • • Dorsiflexion of ankle joint Extension of all toes (extensor hallucis longus and extensor digitorum longus) • Inversion of the foot After its bifurcation past the ankle joint, the lateral branch of the deep peroneal nerve innervates the extensor digitorum brevis and the extensor hallucis brevis The medial branch supplies the web space between the first and second digits. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 39 Important Regions 169 Femoral Triangle Anatomy Boundaries Superiorly Laterally Medially Floor Roof Inguinal ligament Sartorius Adductor longus Iliopsoas, adductor longus and pectineus • Fascia lata and Superficial fascia • Superficial inguinal lymph nodes (palpable below the inguinal ligament) • Long saphenous vein Contents • Femoral vein (medial to lateral) • Femoral artery-pulse palpated at the mid inguinal point • Femoral nerve • Deep and superficial inguinal lymph nodes • Lateral cutaneous nerve • Great saphenous vein • Femoral branch of the genitofemoral nerve • • 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA The iliacus lies posterior to the femoral nerve in the femoral triangle. The femoral sheath lies anterior to both the iliacus and pectineus. 40 Femoral Canal 170 The femoral canal lies at the medial aspect of the femoral sheath. The femoral sheath is a fascial tunnel containing both the femoral artery laterally and femoral vein medially. The canal lies medial to the vein. Borders of the femoral canal Laterally Medially Anteriorly Posteriorly Femoral vein Lacunar ligament Inguinal ligament Pectineal ligament Contents • Lymphatic vessels • Cloquet's lymph node Physiological significance Allows the femoral vein to expand to allow for increased venous return to the lower limbs. Pathological significance As a potential space, it is the site of femoral hernias. The relatively tight neck places these at high risk of strangulation. Adductor Canal • • Also called Hunter's or subsartorial canal Immediately distal to the apex of the femoral triangle, lying in the middle third of the thigh. Canal terminates at the adductor hiatus. Borders Laterally Posteriorly Roof Vastus medialis muscle Adductor longus, adductor magnus Sartorius Contents Saphenous nerve Superficial femoral artery Superficial femoral vein (posterior to the artery in the upper part then posterolat.`) 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 41 Popliteal Fossa 171 Boundaries of the popliteal fossa Laterally Biceps femoris above, lateral head of gastrocnemius and plantaris below Medially Semimembranosus and semitendinosus above, medial head of gastrocnemius below Floor Popliteal surface of the femur, posterior ligament of knee joint and popliteus muscle Roof Superficial and deep fascia Contents • Popliteal artery and vein • Small saphenous vein • Common peroneal nerve • Tibial nerve • Posterior cutaneous nerve of the thigh • Genicular branch of the obturator nerve • Lymph nodes The tibial nerve lies superior to the vessels in the inferior aspect of the popliteal fossa. In the upper part of the fossa the tibial nerve lies lateral to the vessels, it then passes superficial to them to lie medially. The popliteal artery is the deepest structure in the popliteal fossa. Pudendal (Alcock’s) Canal The pudendal canal is located along the lateral wall of the ischioanal fossa at the inferior margin of the obturator internus muscle. It extends from the lesser sciatic foramen to the posterior margin of the urogenital diaphragm. It conveys the internal pudendal vessels and nerve. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 42 172 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 43 Foot - Anatomy 173 Arches of the foot The foot is conventionally considered to have two arches. • The longitudinal arch is higher on the medial than on the lateral side. The posterior part of the calcaneum forms a posterior pillar to support the arch. The lateral part of this structure passes via the cuboid bone and the lateral two metatarsal bones. The medial part of this structure is more important. The head of the talus marks the summit of this arch, located between the sustentaculum tali and the navicular bone. The anterior pillar of the medial arch is composed of the navicular bone, the three cuneiforms and the medial three metatarsal bones. • The transverse arch is situated on the anterior part of the tarsus and the posterior part of the metatarsus. The cuneiforms and metatarsal bases narrow inferiorly, which contributes to the shape of the arch. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 44 Intertarsal joints Sub talar joint 174 Formed by the cylindrical facet on the lower surface of the body of the talus and the posterior facet on the upper surface of the calcaneus. The facet on the talus is concave anteroposteriorly, the other is convex. The synovial cavity of this joint does not communicate with any other joint. Talocalcaneonavicular The anterior part of the socket is formed by the concave articular surface of the navicular joint bone, posteriorly by the upper surface of the sustentaculum tali. The talus sits within this socket Calcaneocuboid joint Highest point in the lateral part of the longitudinal arch. The lower aspect of this joint is reinforced by the long plantar and plantar calcaneocuboid ligaments. Transverse tarsal joint The talocalcaneonavicular joint and the calcaneocuboid joint extend across the tarsus in an irregular transverse plane, between the talus and calcaneus behind and the navicular and cuboid bones in front. This plane is termed the transverse tarsal joint. Cuneonavicular joint Formed between the convex anterior surface of the navicular bone and the concave surface of the the posterior ends of the three cuneiforms. Intercuneiform joints Between the three cuneiform bones. Cuneocuboid joint Between the circular facets on the lateral cuneiform bone and the cuboid. This joint contributes to the tarsal part of the transverse arch. A detailed knowledge of the joints is not required for MRCS Part A. However, the contribution they play to the overall structure of the foot should be appreciated 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 45 175 Nerves in the foot Lateral plantar nerve Passes anterolaterally towards the base of the 5th metatarsal between flexor digitorum brevis and flexor accessorius. On the medial aspect of the lateral plantar artery. At the base of the 5th metatarsal it splits into superficial and deep branches. Medial plantar nerve Passes forwards with the medial plantar artery under the cover of the flexor retinaculum to the interval between abductor hallucis and flexor digitorum brevis on the sole of the foot. Plantar arteries Arise under the cover of the flexor retinaculum, midway between the tip of the medial malleolus and the most prominent part of the medial side of the heel. • Medial plantar artery. Passes forwards medial to medial plantar nerve in the space between abductor hallucis and flexor digitorum brevis.Ends by uniting with a branch of the 1st plantar metatarsal artery. • Lateral plantar artery. Runs obliquely across the sole of the foot. It lies lateral to the lateral plantar nerve. At the base of the 5th metatarsal bone it arches medially across the foot on the metatarsals Dorsalis pedis artery This vessel is a direct continuation of the anterior tibial artery. It commences on the front of the ankle joint and runs to the proximal end of the first metatarsal space. Here is gives off the arcuate artery and continues forwards as the first dorsal metatarsal artery. It is accompanied by two veins throughout its length. It is crossed by the extensor hallucis brevis Ligaments of the Intertarsal Joints Ligament Interosseous talocalcaneal Calcaneocuboid/calcaneonavicular Calcaneocuboid-metatarsal Plantar calcaneocuboid Plantar calcaneonavicular Tarsometatarsal Common Name Cervical Bifurcate Long plantar Short plantar Spring Lisfranc Origin Talus Calcaneus Calcaneus Calcaneus Sustentaculum tali Medial cuneiform Foot Neuromuscular Interactions Foot Function Muscle Inversion Tibialis anterior Tibialis posterior Dorsiflexion Tibialis anterior, extensor digitorum longus, extensor hallucis longus Eversion Plantar flexion Peroneus longus and peroneus brevis Gastrocnemius-soleus complex, flexor digitorum longus, flexor hallucis longus, tibialis posterior (also hindfoot inverter) 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Insertion Calcaneus Cuboid and navicular Cuboid and first to fifth metatarsals Cuboid Navicular Second metatarsal base Innervation Deep peroneal nerve (L4) Tibial nerve (S1) Deep peroneal nerve: tibialis anterior (L4), extensor digitorum longus, and extensor hallucis longus (L5) Superficial peroneal nerve (S1) Tibial nerve (S1) 46 Joints of LL Hip Joint • • • • • • Head of femur articulates with acetabulum of the pelvis Both covered by articular hyaline cartilage The acetabulum forms at the union of the ilium, pubis, and ischium The triradiate cartilage (Y-shaped growth plate) separates the pelvic bones The acetabulum holds the femoral head by the acetabular labrum Normal angle between femoral head and femoral shaft is 130o 176 Mnemonic lateral hip rotators: P-GO-GO-Q (top to bottom) • Piriformis • Gemellus superior • Obturator internus • Gemellus inferior • Obturator externus • Quadratus femoris Ligaments • Transverse ligament: joints anterior and posterior ends of the articular cartilage • Head of femur ligament (ligamentum teres): acetabular notch to the fovea. Contains arterial supply to head of femur in children. • Extracapsular ligaments • Iliofemoral ligament: inverted Y shape. Anterior iliac spine to the trochanteric line • Pubofemoral ligament: acetabulum to lesser trochanter • Ischiofemoral ligament: posterior support. Ischium to greater trochanter. Blood supply Medial circumflex femoral and lateral circumflex femoral arteries (Branches of profunda femoris). Also from the inferior gluteal artery. These form an anastomosis and travel to up the femoral neck to supply the head. Nerve supply of lateral hip rotators • Piriformis: ventral rami S1, S2 • Obturator internus: nerve to obturator internus • Superior gemellus: nerve to obturator internus • Inferior gemellus: nerve to quadratus femoris • Quadrator femoris: nerve to quadrator femoris 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 47 Knee Joint 177 The knee joint is a synovial joint, the largest and most complicated. It consists of two condylar joints between the femur and tibia and a sellar joint between the patella and the femur. The tibiofemoral articular surfaces are incongruent, however, this is improved by the presence of the menisci. The degree of congruence is related to the anatomical position of the knee joint and is greatest in full extension. Knee joint compartments Tibiofemoral • Comprised of the patella/femur joint, lateral and medial compartments (between femur condyles and tibia) • Synovial membrane and cruciate ligaments partially separate the medial and lateral compartments Patellofemoral • Ligamentum patellae • Actions: provides joint stability in full extension Fibrous capsule The capsule of the knee joint is a complex, composite structure with contributions from adjacent tendons. Anterior The capsule does not pass proximal to the patella. It blends with the tendinous expansions of vastus fibres medialis and lateralis Posterior These fibres are vertical and run from the posterior surface of the femoral condyles to the posterior fibres aspect of the tibial condyle Medial fibres Attach to the femoral and tibial condyles beyond their articular margins, blending with the tibial collateral ligament Lateral fibres Attach to the femur superior to popliteus, pass over its tendon to head of fibula and tibial condyle Bursae Anterior Laterally Medially Posterior • • • • • • • • • Subcutaneous prepatellar bursa; between patella and skin Deep infrapatellar bursa; between tibia and patellar ligament Subcutaneous infrapatellar bursa; between distal tibial tuberosity and skin Bursa between lateral head of gastrocnemius and joint capsule Bursa between fibular collateral ligament and tendon of biceps femoris Bursa between fibular collateral ligament and tendon of popliteus Bursa between medial head of gastrocnemius and the fibrous capsule Bursa between tibial collateral ligament and tendons of sartorius, gracilis and semitendinosus Bursa between the tendon of semimembranosus and medial tibial condyle and medial head of gastrocnemius Highly variable and inconsistent Ligaments Medial collateral ligament Lateral collateral ligament Anterior cruciate ligament Posterior cruciate ligament Patellar ligament Menisci Medial and lateral menisci compensate for the incongruence of the femoral and tibial condyles. Composed of fibrous tissue. Medial meniscus is attached to the tibial collateral ligament. Lateral meniscus is attached to the loose fibres at the lateral edge of the joint and is separate from the fibular collateral ligament. The lateral meniscus is crossed by the popliteus tendon. Nerve supply The knee joint is supplied by the femoral, tibial and common peroneal divisions of the sciatic and by a branch from the obturator nerve. Hip pathology pain may be referred to the knee. Blood supply Genicular branches of the femoral artery, popliteal and anterior tibial arteries all supply the knee joint. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 48 178 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 49 Ligaments of the Knee Ligament Retinacular Posterior fibers Oblique popliteal Deep MCL Superficial MCL Arcuate Lateral collateral Anterior cruciate Posterior cruciate Coronary Wrisberg 179 Origin Vastus medialis and vastus lateralis Femoral condyles Semimembranosus tendon Medial epicondyle Medial epicondyle Lateral femoral condyle, over popliteus Lateral epicondyle Anterior intercondylar tibia Posterior sulcus of tibia Meniscus Posterolateral meniscus Humphrey Posterolateral meniscus Transverse meniscal Anterolateral meniscus MCL, medial collateral ligament. 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA Insertion Tibial condyles Function Forms anterior capsule Tibial condyles Lateral femoral condyle/posterior capsule Medial meniscus Medial condyle of tibia Posterior tibia/fibular head Forms posterior capsule Strengthens capsule Lateral fibular head Posteromedial lateral femoral condyle Anteromedial femoral condyle Tibial periphery Medial femoral condyle (behind posterior cruciate ligament) Medial femoral condyle (in front) Anteromedial meniscus Resists varus force Limits hyperextension/sliding Holds medial meniscus to femur Resists valgus force Posterior support Prevents hyperflexion/sliding Meniscal attachment Stabilizes lateral meniscus Stabilizes lateral meniscus Stabilizes menisci 50 180 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 51 Ankle Joint 181 The ankle joint is a synovial joint composed of the tibia and fibula superiorly and the talus inferiorly. Ligaments of the ankle joint • Deltoid ligament (medially) • Lateral collateral ligament • Talofibular ligaments (both anteriorly and posteriorly) The calcaneofibular ligament is separate from the fibrous capsule of the joint. The two talofibular ligaments are fused with it. The components of the syndesmosis are • Antero-inferior tibiofibular ligament • Postero-inferior tibiofibular ligament • Inferior transverse tibiofibular ligament • Interosseous ligament Movements at the ankle joint • Plantar flexion (55 degrees) • Dorsiflexion (35 degrees) • Inversion and eversion movements occur at the level of the sub talar joint Nerve supply Branches of deep peroneal and tibial nerves. Ankle Joint Ligaments Ligament Capsule Deltoid Tibionavicular Tibiocalcaneal Posterior tibiotalar Anterior tibiotalar Anterior tibiofibular Posterior tibiofibular Calcaneofibular Origin Tibia Medial malleolus Medial malleolus Medial malleolus Medial malleolus Medial malleolus Lateral malleolus Lateral malleolus Lateral malleolus Insertion Talus Medial malleolus Navicular tuberosity Sustentaculum tali Inner side of talus Medial surface of talus Transversely to talus anteriorly Transversely to talus posteriorly Obliquely to calcaneus posteriorly 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 52 182 Structures posterior to the medial malleolus: Deep to flexor retinaculum (Posteromedially) Tom Does Very Nice Hats • Tibialis posterior tendon • flexor Digitorum longus • posterior tibial Vessels • posterior tibial Nerve • Hallucis longus Structures deep to ext retinaculum (Anterior): Tom Has Very Nice Dogs & Pigs • Tibialis anterior • ext Hallucis longus • anterior tibial Vessels • anterior tibial Nerve • extensor Digitorum longus • Peroneus tertius 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 53 Surface Anatomy 1E. ANATOMY (LOWER LIMB) – MRCS NOTES - REDA 183 54 184 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA Lumbar puncture ............................................................................................................................................ 2 Vertebral column ............................................................................................................................................ 3 Spinal cord....................................................................................................................................................... 4 Upper Vs Lower motor neurone lesions - Facial nerve ................................................................................. 5 Sympathetic Nervous System - Anatomy ...................................................................................................... 6 Pharyngeal arches ........................................................................................................................................... 7 Levels ............................................................................................................................................................... 8 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 1 Lumbar puncture 185 Lumbar punctures are performed to obtain cerebrospinal fluid. In adults, the procedure is best performed at the level of L3/L4 or L4/5 interspace. These regions are below the termination of the spinal cord at L1. During the procedure the needle passes through: • The supraspinous ligament which connects the tips of spinous processes and the interspinous ligaments between adjacent borders of spinous processes • Then the needle passes through the ligamentum flavum, which may cause a give as it is penetrated • A second give represents penetration of the needle through the dura mater into the subarachnoid space. Clear CSF should be obtained at this point 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 2 Vertebral column • • 186 There are 7 cervical, 12 thoracic, 5 lumbar, and 5 sacral vertebrae. The spinal cord segmental levels do not necessarily correspond to the vertebral segments. For example, while the C1 cord is located at the C1 vertebra, the C8 cord is situated at the C7 vertebra. While the T1 cord is situated at the T1 vertebra, the T12 cord is situated at the T8 vertebra. The lumbar cord is situated between T9 and T11 vertebrae. The sacral cord is situated between the T12 to L2 vertebrae. Cervical vertebrae The interface between the first and second vertebra is called the atlantoaxis junction. The C3 cord contains the phrenic nucleus. Muscle Root value Deltoid C5,6 Biceps C5,6 Wrist extensors C6-8 Triceps C6-8 Wrist flexors C6-T1 Hand muscles C8-T1 Thoracic vertebrae The thoracic vertebral segments are defined by those that have a rib. The spinal roots form the intercostal nerves that run on the bottom side of the ribs and these nerves control the intercostal muscles and associated dermatomes. Lumbosacral vertebrae Form the remainder of the segments below the vertebrae of the thorax. The lumbosacral spinal cord, however, starts at about T9 and continues only to L2. It contains most of the segments that innervate the hip and legs, as well as the buttocks and anal regions. Cauda Equina The spinal cord ends at L1-L2 vertebral level. The tip of the spinal cord is called the conus. Below the conus, there is a spray of spinal roots that is called the cauda equina. Injuries below L2 represent injuries to spinal roots rather than the spinal cord proper. 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 3 Spinal cord 187 • • Located in a canal within the vertebral column that affords it structural support. Rostrally it continues to the medulla oblongata of the brain and caudally it tapers at a level corresponding to the L12 interspace (in the adult), a central structure, the filum terminale anchors the cord to the first coccygeal vertebra. • The spinal cord is characterised by cervico-lumbar enlargements and these, broadly speaking, are the sites which correspond to the brachial and lumbar plexuses respectively. The spinal cord is approximately 45cm in men and 43cm in women. The denticulate ligament is a continuation of the pia mater (innermost covering of the spinal cord) which has intermittent lateral projections attaching the spinal cord to the dura mater and suspends the spinal cord in the dural sheath. There are some key points to note when considering the surgical anatomy of the spinal cord: • During foetal growth the spinal cord becomes shorter than the spinal canal, hence the adult site of cord termination at the L1-2 level, while in neonates it’s L3. • Due to growth of the vertebral column the spine segmental levels may not always correspond to bony landmarks as they do in the cervical spine. • The spinal cord is incompletely divided into two symmetrical halves by a dorsal median sulcus and ventral median fissure. Grey matter surrounds a central canal that is continuous rostrally with the ventricular system of the CNS. • The grey matter is sub divided cytoarchitecturally into Rexeds laminae. • Afferent fibres entering through the dorsal roots usually terminate near their point of entry but may travel for varying distances in Lissauers tract. In this way they may establish synaptic connections over several levels • At the tip of the dorsal horn are afferents associated with nociceptive stimuli. The ventral horn contains neurones that innervate skeletal muscle. The key point to remember when revising CNS anatomy is to keep a clinical perspective in mind. So it is worth classifying the ways in which the spinal cord may become injured. These include: • Trauma either direct or as a result of disc protrusion • Neoplasia either by direct invasion (rare) or as a result of pathological vertebral fracture • Inflammatory diseases such as Rheumatoid disease, or OA (formation of osteophytes compressing nerve roots etc. • Vascular either as a result of stroke (rare in cord) or as complication of aortic dissection • Infection historically diseases such as TB, epidural abscesses. The anatomy of the cord will, to an extent dictate the clinical presentation. Some points/ conditions to remember: • Brown- Sequard syndrome-Hemisection of the cord producing ipsilateral loss of proprioception and upper motor neurone signs, plus contralateral loss of pain and temperature sensation. The explanation of this is that the fibres decussate at different levels. • Lesions below L1 will tend to present with lower motor neurone signs 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 4 Upper Vs Lower motor neurone lesions - Facial nerve 188 The nucleus of the facial nerve is located in the caudal aspect of the ventrolateral pontine tegmentum. Its axons exit the ventral pons medial to the spinal trigeminal nucleus. Any lesion occurring within or affecting the corticobulbar tract is known as an upper motor neuron lesion. Any lesion affecting the individual branches (temporal, zygomatic, buccal, mandibular and cervical) is known as a lower motor neuron lesion. Branches of the facial nerve leaving the facial motor nucleus (FMN) for the muscles do so via both left and right posterior (dorsal) and anterior (ventral) routes. In other words, this means lower motor neurons of the facial nerve can leave either from the left anterior, left posterior, right anterior or right posterior facial motor nucleus. The temporal branch travels out from the left and right posterior components. The inferior four branches do so via the left and right anterior components. The left and right branches supply their respective sides of the face (ipsilateral innervation). Accordingly, the posterior components receive motor input from both hemispheres of the cerebral cortex (bilaterally), whereas the anterior components receive strictly contra-lateral input. This means that the temporal branch of the facial nerve receives motor input from both hemispheres of the cerebral cortex whereas the zygomatic, buccal, mandibular and cervical branches receive information from only contralateral hemispheres. Now, because the anterior FMN receives only contralateral cortical input whereas the posterior receives that which is bilateral, a corticobulbar lesion (UMN lesion) occurring in the left hemisphere would eliminate motor input to the right anterior FMN component, thus removing signaling to the inferior four facial nerve branches, thereby paralyzing the right mid- and lower-face. The posterior component, however, although now only receiving input from the right hemisphere, is still able to allow the temporal branch to sufficiently innervate the entire forehead. This means that the forehead will not be paralyzed. The same mechanism applies for an upper motor neuron lesion in the right hemisphere. The left anterior FMN component no longer receives cortical motor input due to its strict contralateral innervation, whereas the posterior component is still sufficiently supplied by the left hemisphere. The result is paralysis of the left mid- and lower-face with an unaffected forehead. On the other hand, a lower motor neuron lesion is a bit different. A lesion on either the left or right side would affect both the anterior and posterior routes on that side because of their close physical proximity to one another. So, a lesion on the left side would inhibit muscle innervation from both the left posterior and anterior routes, thus paralyzing the whole left side of the face (Bells Palsy). With this type of lesion, the bilateral and contalateral inputs of the posterior and anterior routes, respectively, become irrelevant because the lesion is below the level of the medulla and the facial motor nucleus. Whereas at a level above the medulla a lesion occurring in one hemisphere would mean that the other hemisphere could still sufficiently innervate the posterior facial motor nucleus, a lesion affecting a lower motor neuron would eliminate innervation altogether because the nerves no longer have a means to receive compensatory contralateral input at a downstream decussation. Upper motor neurone lesions of the facial nerve- Paralysis of the lower half of face. Lower motor neurone lesion- Paralysis of the entire ipsilateral face. 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 5 Sympathetic Nervous System - Anatomy 189 The cell bodies of the pre-ganglionic efferent neurones lie in the lateral horn of the grey matter of the spinal cord in the thoraco-lumbar regions. The pre-ganglionic efferents leave the spinal cord at levels T1-L2. These pass to the sympathetic chain. Lateral branches of the sympathetic chain connect it to every spinal nerve. These post ganglionic nerves will pass to structures that receive sympathetic innervation at the periphery. Sympathetic chains These lie on the vertebral column and run from the base of the skull to the coccyx. Cervical Lie anterior to the transverse processes of the cervical vertebrae and posterior to the carotid sheath. region Thoracic Lie anterior to the neck of the upper ribs and lateral sides of the lower thoracic vertebrae. They are region covered by the parietal pleura Lumbar Enter by passing posterior to the medial arcuate ligament. Lie anteriorly to the vertebrae and medial region to psoas major. Sympathetic ganglia • Superior cervical ganglion lies anterior to C2 and C3. • Middle cervical ganglion (if present) C6 • Stellate ganglion- anterior to transverse process of C7, lies posterior to the subclavian artery, vertebral artery and cervical pleura. • Thoracic ganglia are segmentally arranged. • There are usually 4 lumbar ganglia. Clinical importance • Interruption of the head and neck supply of the sympathetic nerves will result in an ipsilateral Horner’s syndrome. • For treatment of hyperhidrosis the sympathetic denervation can be achieved by removing the second and third thoracic ganglia with their rami. Removal of T1 will cause a Horners syndrome and is therefore not performed. • In patients with vascular disease of the lower limbs a lumbar sympathetomy may be performed, either radiologically or (more rarely now) surgically. The ganglia of L2 and below are disrupted. If L1 is removed, then ejaculation may be compromised (and little additional benefit conferred as the preganglionic fibres do not arise below L2. 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA 6 190 Pharyngeal arches These develop during the fourth week of embryonic growth from a series of mesodermal outpouchings of the developing pharynx. They develop and fuse in the ventral midline. Pharyngeal pouches form on the endodermal side between the arches. There are 6 pharyngeal arches, the fifth does not contribute any useful structures and often fuses with the sixth arch. Pharyngeal arches Arch Muscular contributions First • Muscles of mastication • Ant. belly of digastric • Mylohyoid • Tensor tympanic • Tensor veli palatini Second • Buccinator • Platysma • Muscles of facial expression • Stylohyoid • Posterior belly of digastric • Stapedius Third • Stylopharyngeus Fourth Sixth • Cricothyroid • All intrinsic muscles of the soft palate • All intrinsic muscles of the larynx (except cricothyroid) Endocrine N/A Artery • Maxillary • External carotid Nerve • Mandibular • Stapes • Styloid process • Lesser horn and upper body of hyoid N/A • Inferior branch of superior thyroid artery • Stapedial artery • Facial • Greater horn and lower part of hyoid • Thymus • Inferior parathyroids • Superior parathyroids • Common and Internal carotid • Glossopharyngeal • Right Subclavian artery • Left aortic arch • Right: Pulmonary artery • Left: Pulmonary artery and ductus arteriosus • Vagus • • • • Skeletal Maxilla Meckel’s cartilage Incus Malleus • Thyroid and epiglottic cartilages • Cricoid, arytenoid and corniculate cartilages 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA n/a • Vagus and recurrent laryngeal nerve 7 Levels 191 Transpyloric plane Level of the body of L1 • Pylorus stomach • Left kidney hilum (L1- left one!) • Fundus of the gallbladder • Neck of pancreas • Duodenojejunal flexure • Superior mesenteric artery • Portal vein • Left and right colic flexure • Root of the transverse mesocolon • 2nd part of the duodenum • Upper part of conus medullaris • Spleen Can be identified by asking the supine patient to sit up without using their arms. The plane is located where the lateral border of the rectus muscle crosses the costal margin. Anatomical planes Subcostal plane Intercristal plane Intertubercular plane Common level landmarks Inferior mesenteric artery Bifurcation of aorta into common iliac arteries Formation of IVC Diaphragm apertures 1F. ANATOMY (MISCELLANEOUS) – MRCS NOTES - REDA Lowest margin of 10th costal cartilage Level of body L4 (highest point of iliac crest) Level of body L5 L3 L4 L5 (union of common iliac veins) • Vena cava T8 • Oesophagus T10 • Aortic hiatus T12 8
