Anatomy Spine

The spine is a flexible column of bones designed to protect the spinal cord, support the weight of the body and provide mobility. Understanding the basic anatomy of the spine (also called the “spinal column” or “vertebral column”) can help you understand how the spine works and why spinal problems occur.

The Vertebrae and Discs

The building blocks of the spine are bones called vertebrae. Each vertebra has a central hole in it, called a “vertebral foramen.” The vertebrae stack on top of each other, and the foramina (plural of foramen) create the spinal canal, through which the spinal cord passes.

The vertebrae also have openings between them, called “intervertebral foramina.” Nerves leave the spinal cord through these side openings to go to other parts of the body.

The large bony part of a vertebra is the vertebral body. Vertebral bodies are the weight-bearing part of the vertebrae. Between the vertebral bodies are intervertebral discs (also called “disks”), which provide cushioning and mobility between the bones.

Each vertebra is connected to the ones above and below it with ligaments between joints, called “facet joints.” These joints allow the spine to rotate and move. Also, numerous muscles surround, support and manipulate the spine.

Regions of the Spine

The cervical spine, or neck region, has seven vertebrae, designated C1-C7. Cervical spine anatomy is a system of bones, ligaments, tendons and muscles that help support and stabilize the neck and head. It also contains nerves and blood vessels.

The thoracic spine (upper and mid back) consists of 12 vertebrae, designated T1-T12. The thoracic spine is the least mobile part of the spine, partly because the rib bones connect to the thoracic vertebrae.

Most people have five vertebrae in the lumbar spine (lower back), designated L1-L5, although a few people are born with a sixth lumbar vertebra. The lumbar spine supports much of the body’s weight, which is one reason that lower back pain is so common. Another part of lumbar anatomy is the “cauda equina,” a bundle of nerves at the lower end of the spinal cord.

The large, flat bone at the base of the lumbar spine is called the sacrum. The sacrum connects to the hip bones at the sacroiliac (SI) joints. At the base of the sacrum is the coccyx, or tailbone.

Curvature of the Spine

The spine has four natural curves. The cervical and lumbar regions curve inward (lordotic) and the thoracic and sacral regions curve outward (kyphotic). The purpose of spinal curves is to help distribute the stress of body weight as the body moves. Abnormal curvature of the spine — such as scoliosis, kyphosis and lordosis — can lead to back pain and other problems.

Resources

University of Maryland Medical Center Staff. (n.d.). A patient’s guide to anatomy and function of the spine. Retrieved March 1, 2010, from http://www.umm.edu/spinecenter/education/anatomy_and_function_of_the_spine.htm

Spine Universe Staff. (n.d.). Vertebral column. Retrieved March 1, 2010, from http://www.spineuniverse.com/anatomy/vertebral-column

Back.com Staff. (n.d.). Lumbar spine. Retrieved March 1, 2010, from http://www.back.com/anatomy-lumbar.html

National Pain Foundation, Inc. Staff. (n.d.). Anatomy of the spine. Retrieved March 1, 2010, from http://www.nationalpainfoundation.org/articles/405/anatomy-of-the-spine

Spine-health.com Staff. (n.d.). Spine anatomy interactive video. Retrieved March 1, 2010, from http://www.spine-health.com/video/spine-anatomy-interactive-video