Spine

The spine, or vertebral column, is a rigid yet flexible structure of bones that extends from the skull to the pelvis. It protects the spinal cord, supports the head and trunk, transmits loads, and provides attachment points for muscles and ligaments that enable movement and posture.

Anatomy and structure: The adult spine typically consists of 24 movable vertebrae plus the sacrum and coccyx. These are grouped into seven cervical, twelve thoracic, and five lumbar vertebrae, with the sacral and coccygeal vertebrae usually fused. Between adjacent vertebrae lie intervertebral discs, which have a gel-like nucleus pulposus surrounded by an outer annulus fibrosus. The spine forms natural curves: cervical and lumbar lordoses (concave) and thoracic and sacral kyphoses (convex). The vertebral canal encloses the spinal cord in the upper regions; in adults, the cord usually ends at about the level of L1–L2, with nerve roots continuing as the cauda equina.

Joints, ligaments, and nerves: The vertebrae articulate at facet joints (zygapophysial joints) and are stabilized by ligaments including the anterior and posterior longitudinal ligaments, ligamentum flavum, and interspinous and supraspinous ligaments. Spinal nerves exit the spinal column through intervertebral foramina, providing motor and sensory innervation to the body.

Function and disorders: The spine supports the skeleton, protects neural elements, and serves as a lever for movement. Common conditions include scoliosis (abnormal lateral curvature), kyphosis or lordosis abnormalities, degenerative disc disease, herniated discs, spinal stenosis, vertebral fractures, and tumors. Diagnosis relies on clinical evaluation and imaging such as X-ray, MRI, or CT. Treatment ranges from physical therapy and medications to injections or surgical interventions like decompression, fusion, or instrumentation, depending on the condition.