The spine is formed by 33 interlocking bones called vertebrae. Between each pair of vertebrae is a disc, a capsule composed of connective tissue surrounding a soft, jellylike center. The discs absorb shock and provide flexibility within the spine.
Spinal discs break down with age, becoming dry, brittle, and less resilient.
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 into the space that surrounds a nerve root or the spinal canal. This condition is known as a herniated disc. 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 conservative treatment and will go away over time. In a few cases, surgery is needed.