The intervertebral disc helps with the movement of the spine by acting similar to the shock absorbers in a car. The outer ring of the disc is made up of thick tendons and houses an interior of flexible, gel-like tissue that absorbs the impact. When weight is placed on it, the disk expands, and when the weight is removed, it returns to its original shape.
When the intervertebral disc begins to deteriorate, flexibility is reduced. If there is tearing of the outer ring, the soft central portion may bulge out and compress the surrounding nerves, causing a number of symptoms.