Neck and Trunk Vertebral Curves The vertebrae are arranged in such a way as to form anterior-posterior (concaveconvex) curves in the vertebral column, which can be seen from the side. These curves provide the vertebral column with much more strength and resilience, approximately 10 times more than if it were a straight rod. Spinal column 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae Sacrum is composed of 5 fused vertebrae Joint Motions The vertebral column is considered triaxial, with motion in all three planes: Flexion Extension Hyperextension Lateral bending Rotation Cervical Spine Atlanto-occipital joint: articulation between the head and C1 (atlas) Primary motion is flexion and extension, however, rotation also occurs between the atlas and axis, with articulation between the dens of the axis and atlas permitting rotation movement. Common Vertebral Column Pathologies Thoracic outlet syndrome: compression of brachial plexus and subclavian artery and vein that runs from neck to axilla. The thoracic outlet is located between the first rib, clavicle and scalene muscles. Torticollis: “twisted neck:” head is laterally bent to one side and rotated toward the opposite side Sciatica: pain that runs down the posterior thigh and leg, d/t pressure on the sciatic nerve Lordosis: abnormally increased curve of the lumbar spine (“swayback”) Flat back: abnormally decreased lumbar curve Kyphosis: abnormally increased thoracic curve Scoliosis: any amount of lateral curve in spinal column Common Vertebral Column Pathologies Spondylosis: degenerative disorder of the vertebral structure and function, which may lead to nerve root and spinal cord compression Spinal stenosis: a narrowing of the vertebral canal Herniated disks: weakness or degeneration of the annulus fibrosus, allowing a portion of the nucleus pulposus to bulge (herniated) through the annulus. Symptoms occur when herniation places pressure on spinal cord or nerve root. L4 and L5 are most common sites for disk lesions. Spondylolysis: vertebral defect in the pars interarticularis (the part of the lamina between the superior and inferior articular processes). Spondylolisthesis: one vertebra slips forward in relation to an adjacent vertebra (commonly L5 slipping anterior on S1) Osteoporosis: disease in which bone is removed faster than it can be laid down, leading to a decrease in bone mass and density Muscles of the Neck and Trunk Neck Sternocleidomastoid Scalenes Prevertebral group (4) Erector spinae group (3) Splenius capitis Splenius cervicis Suboccipital group (4) Muscles of the Neck and Trunk Trunk Rectus abdominis External oblique Internal oblique Transverse abdominis Erector spinae group (3) Transversospinalis group (3) Interspinales Intertransversarii Quadratus lumborum Sternocleidomastoid Sternocleidomastoid O: Sternum and clavicle I: Mastoid process A: Bilaterally: flexes neck, hyperextends head Unilaterally: laterally bends the neck; rotates head to opposite side N: Accessory nerve (cranial nerve XI); second and third cervical nerves Scalene Scalene O: Transverse processes of the cervical vertebrae I: First and second ribs A: Bilaterally: assists in neck flexion Unilaterally: neck lateral bending N: Lower cervical nerve Prevertebral Group Longus colli O: Bodies and transverse processes of C3T2 I: Transverse processes and bodies of C1C6 A: Flex neck Longus capitis Longus capitis O: Transverse processes of C3-C6 I: Occipital bone A: Flex head Rectus capitis anterior Rectus capitis anterior O: Atlas I: Occipital bone A: Flex head Rectus capitis lateralis Rectus capitis lateralis O: Transverse process of atlas I: Occipital bone A: Laterally bends head Suboccipital Muscles Suboccipital Muscles Obliquus capitis superior: extension Obliquus capitis inferior: extension, lateral bending, rotation to the same side Rectus capitis posterior minor: extension Rectus capitis posterior major: extension, lateral bending, rotation to the same side All suboccipital muscles are located posteriorly Splenius Capitis Splenius Capitis O: Lower half of nuchal ligament; spinous processes of C7 through T3 I: Lateral occipital bone; mastoid process A: Bilaterally: extend head and neck Unilaterally: rotate and laterally bend the head to same side N: Middle and lower cervical nerves Splenius Cervicis Splenius Cervicis O: Spinous processes of T3 thorugh T6 I: Transverse processes of C1 through C3 A: Bilaterally: extend neck Unilaterally: rotate and laterally bend the neck to same side N: Middle and lower cervical nerves Muscles of the Trunk Rectus Abdominis Rectus Abdominis O: Pubis I: Xiphoid process and costal cartilages of fifth, sixth, and seventh ribs A: Trunk flexion; compression of abdomen N: Seventh through twelfth intercostal nerves External Oblique External Oblique O: Lower eight ribs laterally I: Iliac crest and linea alba A: Bilaterally: trunk flexion; compression of abdomen Unilaterally: lateral bending; rotation to opposite side N: Eighth through twelfth intercostal, iliohypogastric, and ilioinguinal nerves Internal Oblique Internal Oblique O: Inguinal ligament, iliac crest, thoracolumbar fascia I: Tenth, eleventh, and twelfth ribs; abdominal aponeurosis A: Bilaterally: trunk flexion; compression of abdomen Unilaterally: lateral bending; rotation to same side N: Eighth through twelfth intercostal, iliohypogastric, and ilioinguinal nerves Transverse Abdominis Transverse Abdominis O: Inguinal ligament, iliac crest, thoracolumbar fascia, and last six ribs I: Abdominal aponeurosis and linea alba A: Compression of abdomen N: Seventh through twelfth intercostal, iliohypogastric, and ilioinguinal nerves Erector Spinae Muscles Iliocostalis Longissimus Spinalis Erector Spinae Muscles Erector Spinae Muscles O: Spinous processes, transverse processes and ribs from the occiput to the sacrum and ilium I: Spinous processes, transverse processes and ribs from the occiput to the sacrum and ilium A: Bilaterally: extend Unilaterally: lateral bend N: Spinal nerves Transversospinalis Muscles Transversospinalis Muscles O: Transverse processes I: Spinous processes of vertebra above A: Bilaterally: extend Unilaterally: rotate to opposite side N: Spinal nerves Interspinales Muscles Interspinales Muscles O: Spinous process below I: Spinous process above A: Trunk extension N: Spinal nerves Intertransversarii Muscles Intertransversarii Muscles O: Transverse process below I: Transverse process above A: Trunk lateral bending N: Spinal nerves Quadratus Lumborum Quadratus Lumborum O: Iliac crest I: Twelfth rib, transverse processes of all five lumbar vertebrae A: Trunk lateral bending N: Twelfth thoracic and first lumbar nerves *Hip hiking (elevation) of one side of the pelvis*