Low back pain can be caused by a number of factors from injuries to the effects of aging. The spinal cord is protected by the vertebrae, which are made of bone. Between each vertebra are soft discs with a ligamentous outer layer. These discs function as shock absorbers to protect the vertebra and the spinal cord. Many of the problems that cause back pain are the result of herniation and degeneration of the intervertebral disc. Degeneration is a process where wear and tear causes deterioration of the disc. Herniations or bulging of the disc are protrusions from the disc that press on surrounding nerves, causing pain and numbness.