The spinal column consists of 33 vertebrae that protect the spinal cord and provide stability to the torso. Between each vertebra is a fibrous bundle of tissue called an intervertebral disc, which acts as a cushion to the spinal column by absorbing the shock and pressure associated with everyday movement.
An intervertebral disc consists of two distinct regions. The firm outer region called the annulus fibrosus maintains the shape of the intervertebral disc. The inner portion, called the nucleus pulposus, is the soft, spongy tissue that enables the disc to function as a shock absorber. Over time, the normal aging process causes the intervertebral discs to degenerate, diminishing their water content and thereby reducing their ability to properly absorb the impact associated with spinal movements.
Excessive pressure, strain, or injury to a rigid disc can cause the disc to tear or bulge. The degeneration of disc size and function will bring the adjacent vertebrae closer to one another, possibly causing impingement and compression of a spinal nerve root. Nerve impingement can result in intermittent low back pain, leg pain, numbness or tingling of the buttocks, depending on the level of impingement.