The bones that form the spine (backbone) are cushioned by round, flat discs. When these discs are damaged from an injury, normal wear and tear, or disease, they may bulge abnormally or break open (rupture) in what is called a herniated or slipped disc.

Spinal discs break down with age, becoming drier, less flexible, and more easily damaged. Injury and prolonged overuse or misuse can speed the formation of tiny tears in a disc's outer covering (capsule).

Excessive pressure on a weakened disc can cause some of the jellylike material in the center of the disc to squeeze through the tears in the capsule, causing the disc to rupture (herniate) into the space that surrounds a nerve root or the spinal canal. A herniated disc can interfere with nerve function, leading to weakness, numbness, or pain in a leg or arm.

In most cases, symptoms of a herniated disc can be managed with nonsurgical treatment and will go away over time. In a few cases, surgery is needed.