Degenerative disc disease
An intervertebral disc, which has suffered the effects of the aging process or the effects of trauma. A disc becomes degenerated over time, often spanning years. Often there are small circumferential tears in the annulus fibrosis, the tough outer covering of the disc. A degenerated disc is also characterized by a loss of its height due to a drying-out of the nucleus pulposus, the gelatinous material inside the disc. It is often caused by a loss of motion between the vertebrae above and below, thus decreasing the mechanical flow of nutrients to the disc.