Intermediate
Technical
IVT
myelin sheath
Pronunciation: MY-uh-lin sheeth
Fatty tissue wrapping around nerve fibers that speeds up electrical signal transmission.
Full Definition
The myelin sheath is a multilayered membrane structure composed primarily of lipids that wraps around the axons of many neurons in the central and peripheral nervous systems. Produced by oligodendrocytes in the CNS and Schwann cells in the PNS, myelin acts as an electrical insulator that dramatically increases the speed of nerve impulse conduction through saltatory conduction. Demyelination, or damage to myelin sheaths, is the hallmark of conditions like multiple sclerosis and contributes to various neurological deficits.
Usage
Usage note: Always use 'sheath' as singular; the plural is 'sheaths.'
In Context
- "Multiple sclerosis is characterized by progressive destruction of myelin sheath in the central nervous system." — Disease description
- "The nerve conduction study showed decreased velocity consistent with myelin sheath dysfunction." — Diagnostic test result
Also known as
myelin
nerve sheath
Don't confuse with
nerve membrane
axolemma