In between each pair of vertebrae is a disc which acts like a soft cushion between the bones. The discs in the spine act as “shock absorbers” for the vertebrae and have also been thought of as “Jelly Doughnuts”. If a disc is damaged, it may bulge or break open. When this happens, it is referred to as a herniated disc. It may also be called a ruptured or a slipped disc.
A herniated disc may be caused by the wear and tear of the disc as you age or, by an injury to the spine. When this happens, the gel inside the disc can be pushed through the outer layer and cause the disc to bulge or rupture. This is analogous to the jelly getting squeezed out of the doughnut.
If the herniated disc is not pressing on a nerve, you may have a backache or no pain at all. This may be the initial insult that leads to degenerative disk disease. However, should the gel come in contact with the nerve, irritation can occur. Extreme, sudden pain is usually the first symptom.
Sciatica, which is pain and numbness in the buttock and down the leg, is the most common symptom of a herniated disc in the lower back. A herniated disc can also cause neck pain and numbness that radiates into either arm.