Disks Your Backs Shock Absorbers - The Anatomy Of Your Back: Back Pain

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Disks: Your back's shock absorbers

An intervertebral disk is tucked between each pair of vertebral bodies and serves as a small shock-absorbing cushion. These disks prevent the vertebrae from scraping against each other. The disks also form universal joints between the vertebrae, permitting normal spinal motion. A normal disk has a jelly-like central part (the nucleus pulposus) and a tougher multilayered fibrous outer covering (the annulus fibrosus) that binds to the adjacent vertebrae. These disks can be likened to miniature jelly donuts or waterbeds.

In view of the many stresses that plague the lumbar spine throughout life, it is little wonder that the disks are the source of many back problems. Indeed, they begin to change relatively early in life — usually after age 30. The nucleus begins to dehydrate, harden, and lose its jelly-like property, while the annulus tends to fragment as its various layers disintegrate. During the early stages of this process, the mechanical function of the disk gradually deteriorates, like a tire losing air. This diminishes the disk's ability to absorb shocks, making the affected intervertebral joint more vulnerable to stress.

Last updated:	January 23, 2007