From the skull base to the pelvis, the spine structure is divided into the three parts: the cervical spine, the thoracic spine and the lumbar spine. The spine's curves form an "S" shape, supporting the body's weight and protecting the spinal cord.
The cervical spine has seven vertebrae - the first two are used neck movement. The thoracic spine has twelve vertebrae - they are connected to the ribs. The lumbar spine normally has five vertebrae - they allow the spine to connect to the pelvis. The lumbar vertebrae are the largest vertebrae, as it carries the body's weight.
Ligaments and fibrous tissues connect all the vertebrae. The spinal canal is in the vertebra center - it lets the spinal cord and nerves to pass through.