Intervertebral discs (or intervertebral fibrocartilage) lie between adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.
The intervertebral disc is composed of two materials: the outer hard fibrous ring called the annulus fibrosus and an inner soft gelatinous core called the nucleus pulposus. The intervertebral disc functions to both absorb shock and allow flexibility of the vertebral column. As the body ages, the integrity of the intervertebral disc declines and causes the inner core of the disc to protrude through the outer layer. The effects of these will be either compression of the nerve roots or the spinal cord, giving rise to radicular or myelopathic symptoms 1).