The whole spine consists of 33 bones called vertebrae. The first seven are the cervical vertebrae.The next twelve vertebrae form the thoracic spine. The five vertebrae below the thoracic form the lumbar spine. The remaining vertebrae form the sacral spine (5 fused vertebrae) and the coccyx (4 fused vertebrae).

The spine ligaments and muscles control movements of the spine. They allow rotation, flexion, extension and lateral bending movements. Intervertebral discs act as cushions between the vertebrae during these movements and axial loading.