Myelin is an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances.
This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells. If myelin is damaged, these impulses slow down. This can cause diseases such as multiple sclerosis.
Multiple sclerosis (MS) is an autoimmune disease that affects the brain and spinal cord (central nervous system).
Calabresi PA. Multiple sclerosis and demyelinating conditions of the central nervous system. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 411.
Myelin. Taber's Medical Dictionary Online. www.tabers.com/tabersonline/view/Tabers-Dictionary/767168/all/myelin. Accessed June 11, 2017.
Myelin and nerve structure - illustration
Myelin is the layer that forms around nerve cells. Its purpose is to speed the transmission of impulses along nerve cells.
Myelin and nerve structure
Review Date: 5/13/2019
Reviewed By: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.