myelin sheath

American  

noun

Anatomy.

1. a wrapping of myelin around certain nerve axons, serving as an electrical insulator that speeds nerve impulses to muscles and other effectors.

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Etymology

Origin of myelin sheath

First recorded in 1895–1900

Example Sentences

MS is a disease of the brain and central nervous system, in which the immune system mistakenly attacks the fatty myelin sheath that normally protects the nerves, like insulation around electric wires.

From BBC • May 29, 2026

These metabolites support the growth and maturation of oligodendrocytes, which in turn helps rebuild the myelin sheath.

From Science Daily • Apr. 15, 2026

Demyelination is the process in which the myelin sheath -- a protective, insulating layer surrounding nerve fibers in the brain and spinal cord -- is damaged or destroyed.

From Science Daily • Jan. 6, 2026

Their findings show that the immune system begins attacking the brain's protective myelin sheath -- the fatty covering that insulates nerve fibers -- much earlier than scientists once believed.

From Science Daily • Oct. 21, 2025

"We know that axons which are regularly stimulated have enhanced myelin sheath thickness," explains Dr. Mihai Stancu, lead author of the paper.

From Science Daily • Mar. 6, 2024