Definition of Myelin

Myelin: The fatty substance that covers and protects nerves. Myelin is a layered tissue that surrounds the nerve fibers (axons). This sheath around the axons acts like a conduit in an electrical system, ensuring that messages sent by axons are not lost en route.

Last Editorial Review: 3/19/2012

Dementia Pictures Slideshow: Disorders of the Brain

Search MedTerms:

Back to MedTerms online medical dictionary A-Z List
Pill Identifier Tool

Need help identifying pills and medications?
Use the pill finder tool on RxList.