Chapter 2: Back: Vertebral Column, Muscles & Spinal Anatomy

The skeletal framework is established by the vertebral column, which consists of approximately thirty-three vertebrae segmented into cervical, thoracic, lumbar, sacral, and coccygeal regions, each exhibiting distinct primary and secondary curvatures to maintain balance and upright posture. The text details the morphology of a typical vertebra, composed of a weight-bearing body and a vertebral arch formed by pedicles and laminae, while highlighting regional variations such as the atlas and axis for head movement, costal facets on thoracic vertebrae for rib articulation, and the fused sacrum. Joint mechanics are explored through the symphyses between vertebral bodies, involving intervertebral discs with an outer anulus fibrosus and inner nucleus pulposus, and the synovial zygapophysial joints that dictate regional flexibility. Stability is reinforced by a robust ligamentous system, including the anterior and posterior longitudinal ligaments running the length of the column, the elastic ligamenta flava connecting laminae, and the supraspinous ligament which transitions into the ligamentum nuchae in the neck. The musculature is systematically categorized into extrinsic groups, which include superficial muscles like the trapezius and latissimus dorsi acting on the upper limbs and intermediate respiratory muscles like the serratus posterior, and intrinsic groups such as the erector spinae and transversospinales that control vertebral posture and movement. Furthermore, the chapter examines the spinal cord's extent, enlargements, and termination at the conus medullaris, along with its protective meningeal coverings (dura, arachnoid, and pia mater) and the arrangement of spinal nerves into anterior and posterior rami. Clinical relevance is integrated throughout, covering conditions such as scoliosis, spina bifida, disc herniation, and fractures, while explaining the anatomical basis for procedures like lumbar punctures and the vascular supply involving the critical artery of Adamkiewicz.