All the vertebrae are constructed with the same basic structure (Fig. 20.4) and have two parts: (i) the body or centrum (i.e. the anterior or ventral part) and ; (ii) the neural arch (i.e. the posterior or dorsal part). The vertebral canal lies between the body and arch, and encloses the spinal cord. The arch bears three processes for attachment of muscles; two transverse processes, one on either side that articulates with ribs, and a spinous process which projects dorsally to which muscles and ligaments are attached. The arch also bears articular processes-(two superior and two inferior) which project rostrally and caudaully respectively. These processes articulate with each other on adjacent vertebrae. Between the successive vertebrae are a pair of small openings called intervertebral foramina for the passage of spinal nerves. Between each of the vertebrae are cartilaginous pads; the intervertebral discs.

The vertebrae are named according to the region in which they lie (i) Cervical-7, (ii) Thoracic-12 (iii) Lumbar-5 (iv) Sacral-5, fused into one sacrum and (v) Coccyl-4, fused into one: the Coccyx.