The spine is composed of a series of bones called vertebrae. There are different areas of the spine, defined by their curvature and function. The seven small vertebrae in the neck make up the cervical spine. The chest area contains the thoracic spine, with 12 vertebrae. The lumbar spine is located at and below your waist. The lumbar spine contains five large vertebrae. The remainder of the lower vertebrae in the spine are fused or shaped differently in formation with the hip and pelvis bones.
The back part of each vertebra arches to form the lamina. The lamina creates a roof-like cover over the back opening in each vertebra. The opening in the center of each vertebra forms the spinal canal. The spinal cord, nerves, and arteries travel through the protective spinal canal. The spinal cord and nerves send messages between your body and brain.
Intervertebral discs are located in between the cervical, thoracic, and lumbar vertebrae. Strong connective tissue forms the discs. Their tough outer layer is the annulus fibrosus. Their gel-like center is the nucleus pulposus. A healthy disc contains about 80% water.
The discs and two small spinal facet joints connect one vertebra to the next. The discs and joints allow movement and provide stability. The discs also act as a shock-absorbing cushion to protect the vertebrae.