The intervertebral disc serves as a cushion between adjacent vertebrae. The covering of (annulus) surrounds the stuffing (“disc material� or nucleus pulposis�).

The intervertebral disc is comprised of three regions referred to as annulus fibrosis, the nucleus pulposus, and the vertebral cartilage endplate.

The intervertebral disc (IVD) is comprised of water, cells (chondrocyte-like cells and fibroblasts), proteoglycans aggregates, and collagen fibers. The outer layer is called the annulus fibrosis it is made up of several layers of interwoven supportive fibers. The vertebral cartilage endplate is comprised of a thin layer of porous cartilage which lies over the bone of the vertebral body.  Nutrition to the inner annulus fibrosis and nucleus pulposus depends on the diffusion of water and small molecular substances across the vertebral endplates. The gel-like center (nucleus pulposis) of the intervertebral disc helps provide stability as well as mobility to the vertebral motion segment. The adaptable gel-like center of the inter vertebral disc also allows deformity of the disc under the weight of the body above.

The outer fibers of the disc referred to as the annular fibers are anchored to the adjacent margin of the cartilage and bone. The annular fibers lie in a crisscross relationship to one another. This interwoven ring of fibers increases the strength of the disc. In an axial section, they are configured somewhat like the slices of an onion.  Under normal circumstances the annular fibers are able to stretch to a small degree without tearing.  The annular fibers are made up of collagen, which is a form of connective tissue.  When collagen fibers are looked at under a microscope they have an appearance similar to a spring.