A disc is a cushion pad between the vertebral bodies. It acts as a shock reducing structure to prevent injury to bone, nerves, and muscles. This disc has a very strong outer ring called the annulus fibrosis and a central bubble-gum-like material called the annulus pulposus. A disc can be deformed by an injury, by recurrent injury or infection, or by degeneration. The disc can broadly bulge, focally protrude or extrude with injury or degeneration.
An acute disc herniation is due to a short complete tear or focal thinning of the strong outer part of the disc (annulus fibrosis) with the inner bubble gum like material protruding through this area. Pain is produced by the disc compressing adjacent nerve roots and injury to the disc. Material from the protruded disc released into adjacent spaces around the nerves produces an inflammatory reaction. A tear of the disc is like a tear or laceration anywhere in the body. Pain is produced by a tear of the outer disc ring.