myelin
Meaning of myelin: Myelin is a fatty insulating layer wrapped around nerve fibers that speeds electrical signaling and protects the underlying nerve from damage.
Definition of myelin
Myelin is a fatty substance that forms a protective, insulating layer around many nerve fibers throughout the brain, spinal cord, and peripheral nerves. It is produced by specialized cells and wraps around the nerve fiber in segments, leaving small uninsulated gaps at regular intervals along its length.
This insulating layer allows electrical signals to travel much faster along a nerve fiber than they would without it, since the signal effectively jumps between the uninsulated gaps rather than traveling continuously along the entire length of the fiber. Myelin also helps protect the underlying nerve fiber from damage.
Damage to myelin disrupts this efficient signal conduction and underlies a group of conditions known as demyelinating diseases, in which nerve signaling slows or fails in the affected areas, producing symptoms that depend on which nerve pathways are involved.
Used in a sentence
Imaging findings were consistent with a loss of myelin in the affected region of the brain.
Good to know
Damage to myelin slows or blocks nerve signaling without necessarily destroying the underlying nerve fiber itself, which is why some demyelinating conditions can partially improve if the myelin layer is repaired.
Word origin
Where “myelin” comes from
Formed from Greek myelos, meaning marrow, reflecting the substance's original description as a marrow like material within nerve fibers.