vertebre

Vertebrae are the bones that form the vertebral column, or spine. Each vertebra consists of a weight‑bearing vertebral body in front and a vertebral arch behind, which together enclose the vertebral foramen through which the spinal cord runs. The arch includes pedicles, laminae, and several bony projections: a spinous process at the back, transverse processes on the sides, and superior and inferior articular processes that form facet joints with adjacent vertebrae. Between most adjacent vertebrae lie intervertebral discs, consisting of an outer annulus fibrosus and an inner nucleus pulposus, which cushion the joints and allow limited motion.

In the adult human, the vertebral column is typically organized into distinct regions: seven cervical, twelve thoracic, and five lumbar vertebrae, followed by five fused sacral vertebrae and four fused coccygeal vertebrae. The topmost vertebra, atlas (C1), supports the skull and lacks a true body, while the next vertebra, axis (C2), has the odontoid process (dens) that acts as a pivot for head rotation. Intervertebral discs lie between most vertebrae, except where vertebrae are fused in the sacrum and coccyx.

Function and clinical relevance: vertebrae protect the spinal cord and exit nerves, support the body's weight, and enable a range of motions in conjunction with discs, ligaments, and muscles. The column exhibits natural curvatures—cervical and lumbar lordoses and thoracic and sacral kyphoses—that help distribute loads. Developmentally, vertebrae arise from somites and undergo resegmentation during formation. Common conditions affecting vertebrae include fractures, herniated discs, spondylosis, scoliosis, and osteoporosis, which can impact mobility and neurological function.