Cervical discs support the neck’s vertebral bones while also enabling flexibility for head movements. Sitting between adjacent cervical vertebrae stacked atop each other, each cervical disc acts as a shock absorber to help the cervical spine handle various stresses and loads.
Video: Cervical Disc Anatomy
Learn how 6 discs in the neck allow the highly mobile cervical spine to move in all directions. Watch Now
There are 6 intervertebral discs in the highly-mobile cervical spine. These cervical discs tend to be thinner than the lumbar discs in the lower back but thicker than the thoracic discs in the less-mobile upper back.
Cervical Disc Anatomy
Each cervical disc has 2 basic components:
- Outer layer. This tough exterior, called the annulus fibrosus, is comprised of collagen fibers that surround and protect the inner core. The annulus fibrosus also distributes the forces placed on the structure.
- Inner core. This soft jelly interior, called the nucleus pulposus, is a loose, fibrous network suspended in mucoprotein gel that is sealed by the annulus fibrosus. The nucleus pulposus helps to provide cushioning and flexibility to the disc.
The discs need to be well-hydrated in order to maintain their strength and softness to serve as the spine’s major carrier of axial load.
With age, the cervical discs lose water, stiffen and become less flexible in adjusting to compression. Such degenerative changes may result in a herniated cervical disc, which is when the disc's inner core extrudes through its outer layer and comes in contact with the nerve root and/or spinal nerve.
In other instances, the cervical disc may degenerate as a result of direct trauma or gradual changes. With no blood supply and very few nerve endings, a cervical disc cannot repair itself.
A vertebral endplate is the transition region between a disc and the adjacent vertebra. The vertebral endplate is thin and comprised of collagen and porous bone, which allows for nutrients and limited amounts of blood to pass into the disc. If a vertebral endplate becomes injured or dysfunctional, fewer nutrients can get to the disc, which may accelerate disc degeneration.
Movement in general seems to increase the amount of nutrients that pass through the vertebral endplates into the discs. Living an active lifestyle, rather than being sedentary, can help nourish the discs.
While the intervertebral discs help provide cushioning and flexibility for the neck, muscle movements are directed by signals sent from the brain through the spinal cord and nerve roots as discussed on the next page.