vértebra

A vértebra is one of the bones that form the vertebral column, the central part of the skeleton known as the spine. Vertebrae protect the spinal cord, provide attachment points for muscles, and help bear and distribute the body's weight during movement and posture.

A typical vertebra consists of an anterior vertebral body and a posterior vertebral arch. The arch is formed by pedicles and laminae and encloses the vertebral foramen, which together with adjacent vertebrae forms the spinal canal that houses the spinal cord and nerves. Each vertebra has a spinous process projecting backward and two transverse processes on either side. Superior and inferior articular facets on the articular processes form joints with neighboring vertebrae. Between adjacent vertebrae lie intervertebral discs, composed of a gel-like nucleus pulposus surrounded by a fibrous annulus fibrosus, which cushion movement and allow limited motion.

Vertebrae are grouped into regional types: cervical (neck), thoracic (mid back), lumbar (lower back), sacral (fused into the sacrum), and coccygeal (fused into the coccyx). Some vertebrae are atypical; for example, the atlas (C1) and axis (C2) support the skull and enable rotation, while the cervical region contains foramina transversaria for the passage of the vertebral arteries.

Function and development: The vertebral column protects the spinal cord, supports the head and trunk, and permits a range of movements. Vertebrae arise from developing somites and ossify with age; many vertebrae fuse in adulthood (as in the sacrum and coccyx). Clinically, vertebrae can be affected by fractures, degenerative disc disease, herniation, stenosis, scoliosis, and other spinal conditions.