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intervertebral disk

 
American Heritage Dictionary:

intervertebral disk

intervertebral disk
(Click to enlarge)
intervertebral disk

profile of lumbar intervertebral disks
(Carlyn Iverson)

n.
A broad disk of fibrocartilage situated between adjacent vertebrae of the spinal column.


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n.

Any of the disks between the bodies of adjacent vertebrae. Also called intervertebral cartilage.

Wikipedia on Answers.com:

Intervertebral disc

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Intervertebral disc
Gray301.png
Median sagittal section of two lumbar vertebræ and their ligaments. (Intervertebral fibrocartilage labeled at center left.)
Gray313.png
Costotransverse articulation. Seen from above. (Intervertebral fibrocartilage labeled at top center .)
Latin disci intervertebrales
Gray's subject #72 289
MeSH Intervertebral+Disk

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.

Contents

Structure

Discs consist of an outer annulus fibrosus, which surrounds the inner nucleus pulposus. The annulus fibrosus consists of several layers of fibrocartilage. The strong annular fibers contain the nucleus pulposus and distribute pressure evenly across the disc. The nucleus pulposus contains loose fibers suspended in a mucoprotein gel with the consistency of jelly. The nucleus of the disc acts as a shock absorber, absorbing the impact of the body's daily activities and keeping the two vertebrae separated. The disc can be likened to a jelly doughnut: whereby the annulus fibrosis is similar to the dough and the nucleus pulposis is the jelly. If one presses down on the front of the doughnut the jelly moves posteriorly or to the back. When one develops a prolapsed disc the jelly/nucleus pulposus is forced out of the doughnut/disc and may put pressure on the nerve located near the disc. This can give one the symptoms of sciatica.

Cervical vertebra with intervertebral disc

There is one disc between each pair of vertebrae, except for the first cervical segment, the atlas. The atlas is a ring around the roughly cone-shaped extension of the axis (second cervical segment). The axis acts as a post around which the atlas can rotate, allowing the neck to swivel. There are a total of twenty four discs in the human spine, which are most commonly identified by specifying the particular vertebrae they separate. For example, the disc between the fifth and sixth cervical vertabrae is designated "C5-6".

Intervertebral disks

Medical conditions related to the intervertebral disc

As people age, the nucleus pulposus begins to dehydrate, which limits its ability to absorb shock. The annulus fibrosus gets weaker with age and begins to tear. While this may not cause pain in some people, in others one or both of these may cause chronic pain.

See also

Additional images

External links


 
 

 

Copyrights:

American Heritage Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
American Heritage Stedman's Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company Read more
Wikipedia on Answers.com. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Intervertebral disc Read more

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