The spinal column consists of 33 stacked vertebrae connected and aligned by various ligaments and muscles, according to the Mayfield Clinic. The spine is the structural backbone for the musculoskeletal system. It protects the spinal cord and provides balance and stability for the body.
The spine includes five sections: seven cervical vertebrae, 12 thoracic vertebrae, five lumbar vertebrae, five fused sacral vertebrae and four fused vertebrae in the coccyx. The vertebrae in the cervical, thoracic and lumbar regions have natural curves designed to distribute weight and maintain balance. Extensor muscles attached to the back of the spine help to stabilize the spine, while flexor muscles, including the abdominal muscles, aid help to bend and lift weight, explains the Mayfield Clinic.
The intervertebral discs that separate the vertebrae keep the bones from rubbing together, notes the Mayfield Clinic. The outer ring of an intervertebral disc consists of fibrous bands and a gel-like center. Discs fill with fluid during the night to help absorb shock and cushion the vertebrae during the day. Vertebrae themselves have three distinct parts: a body, a vertebral arch and vertebral processes. Vertebral arches create the spinal canal, which contains the spinal cord, ligaments, nerves and blood vessels. Spinal nerves enter and exit the spinal cord between each vertebra. Seven processes on each vertebral arch form attachment points for muscles. Three major spinal ligaments hold the vertebrae together and stabilize the spine. Two ligaments are continuous and prevent excessive vertebral body movement, and the third ligament attaches between each vertebra. Each vertebra has several facet joints, or links with the vertebrae above and below, that allow for complete range of motion.