Neurilemma

Part of speech: noun

Definitions

1. The outermost layer surrounding a nerve fiber, composed mainly of Schwann cell cytoplasm that enables regeneration of peripheral nerves ; a cellular sheath that encloses the axon and myelin sheath in peripheral nervous system fibers ; a protective covering made of Schwann cell material that facilitates repair and regrowth of damaged nerve cells
2. A thin, membranous layer encasing the myelin insulation of a neuron in the peripheral nervous system, aiding nerve fiber repair ; a specialized Schwann cell plasma that surrounds the axon, contributing to nerve regeneration and electrical insulation ; the external envelope of a nerve fiber important for restoring function after injury
3. The cellular sheath around the myelin that protects peripheral nerve fibers and promotes regeneration ; a layer formed by Schwann cells wrapping the axon and supporting nerve healing and function restoration ; an outer membrane wall essential for peripheral nerve endurance and ability to repair after damage

Etymology: Schwann cells wrap around the axons of peripheral nerves, and the sheath they form around the myelin is called the neurilemma. The name comes from the Greek "neûron," meaning sinew or nerve, which gave English the combining form "neuro-." The "-lemma" element is Greek for a husk or rind, a sense that fits a thin outer covering. The word is a compound, formed from "neuri-," a variant of "neuro-," plus "lemma." Its parts therefore describe the structure directly: a nerve's covering. It is a technical coinage, not a term that existed in classical Greek, since the anatomy it names was only understood with modern microscopy.

Synonyms: nerve sheath, myelin sheath