Basic Anatomy of the Spine
Our spine holds up our head, shoulders, and upper body. It helps us to stand up straight, gives us the flexibility to bend and twist, and protects the spinal cord. It is divided into three segments: the c-shaped curve of the cervical spine in the neck, the reverse c-shaped curve of the thoracic spine in the chest, and the c-shaped curve of the lumbar spine in the lower back.
Five unique components work together to compose the spine and maintain its function.
- Vertebrae: These are the bones stacked from the lumbar through the cervical spine. They vary in size, and create a canal that protects the spinal cord and supports the body. The seven smallest vertebrae are in the cervical spine that begins at the base of the skull. Twelve larger vertebrae compose the thoracic spine and connect to the rib cage. The largest five vertebrae are in the lumbar spine, where they carry more of the body’s weight.
- Spinal Cord: The spinal cord extends the entire length of the spine, traveling through the central canal in the middle of each stacked vertebra. Nerves branch out from the spinal cord through openings in the vertebrae to conduct messages between the brain and muscles. At the first and second lumbar vertebrae, the spinal cord continues as nerve roots that exit the spinal canal through vertebrae openings. Some form the sciatic nerves extending down into the legs.
- Muscles and Ligaments: These tissues support and stabilize the spine and upper body. The ligaments connect the vertebrae, and hold the spinal column in place.
- Intervertebral Discs: These flat round cushions sit between the vertebrae. They are supplied by nerve endings, and provide flexibility and strength. Because the discs are able to expand with movement, they allow for motion, and act as shock absorbers.
- Facet Joints: These small joints at the back of the vertebrae have a cartilage surface, much like a knee or hip joint. These joints allow rotation of the spine, but may also develop arthritis, like any other joint.
When all of the components of the spine are healthy and working in concert, we can enjoy life with a full range of strong, flexible motion.