Definition

Myelin is an insulating layer that forms around nerves. It is made up of protein and fatty substances. The purpose of the myelin sheath is to allow rapid and efficient transmission of impulses along the nerve cells. If the myelin is damaged, the impulses are disrupted. This can cause diseases like multiple sclerosis.

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Review Date:7/28/2005
Reviewed By: Kevin Sheth, M.D., Department of Neurology, Brigham and Women's Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA. Review provided by VeriMed Healthcare Network.