myelin sheath

myelin sheath

n.

The insulating envelope of myelin that surrounds the core of a nerve fiber or axon and facilitates the transmission of nerve impulses. In the peripheral nervous system, the sheath is formed from the cell membrane of the Schwann cell and, in the central nervous system, from oligodendrocytes. Also called medullary sheath.

Thesaurus

Noun

1.

myelin sheath - a layer of myelin encasing (and insulating) the axons of medullated nerve fibers medullary sheath sheath, case - an enveloping structure or covering enclosing an animal or plant organ or part axolemma - outer membrane covering an axon medullated nerve fiber, myelinated nerve fiber - a nerve fiber encased in a sheath of myelin nodes of Ranvier, Ranvier's nodes - small gaps in the myelin sheath of medullated axons oligodendria, oligodendroglia - tissue consisting of glial cells with sheetlike processes that form the myelin sheath of nerve fibers medulla, myelin, myeline - a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers