Anatomy of Degenerative Disc Disease

To best understand degenerative disc disease, it helps to know the anatomy of your back. Your back, or spine, is made up of many parts. Your backbone, also called your vertebral column, provides support and protection. It consists of 25 vertebrae (bones). There are discs, the source of the pain in degenerative disc disease, between each of the vertebra that act like pads or shock absorbers. Each disc is made up of a tire-like outer band called the annulus fibrosus and a gel-like inner substance called the nucleus pulposus. Together, the vertebrae and the discs provide a protective tunnel (the spinal canal) to house the spinal cord and spinal nerves. These nerves run down the center of the vertebrae and exit to various parts of the body.

Parts of the Spine

Your back also has muscles, ligaments, tendons, and blood vessels. Muscles are strands of tissues that act as the source of power for movement. Ligaments are the strong, flexible bands of fibrous tissue that link the bones together, and tendons connect muscles to bones and discs. Blood vessels provide nourishment. These parts all work together to help you move about, and it is the same parts that can cause pain in degenerative disc disease.

Degenerative disc disease weakens the spine, which can ultimately lead to a herniated (bulging) disc or a ruptured disc. When this happens, the soft nucleus pulposus escapes, either on one side or both sides, through a tear in the annulus fibrosus. This bulge may compress a nerve. The amount of pain associated with a herniated disc rupture often depends upon the amount of material that breaks through the annulus fibrosus—and whether it compresses a nerve or not. Any of these conditions can cause inflammation and pain in degenerative disc disease.