The structure of the spine is such that at an early age the human body has 33 vertebrae, 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal. As we age, the 4 sacral vertebrae fuse to form a tailbone. The spine supports the skull at the upper end, attaches to the ribs in the middle, and connects to the hip bones at the lower end. The spine also serves as the back wall of the thorax, abdomen and pelvis. The spine is connected by ligaments.
The functions of the spine are to support the body, conduct loads, move, maintain stability, protect the spinal cord, and allow for flexion and extension movements, left and right lateral bending, and left and right rotation. The spinal canal, consisting of the cervical, thoracic, lumbar and sacral vertebrae, contains the nerves and spinal cord.