myelin sheath
noun
: the insulating covering that surrounds an axon with multiple spiral layers of myelin, that is discontinuous at the nodes of Ranvier, and that increases the speed at which a nerve impulse can travel along an axon
called also medullary sheath
Examples of myelin sheath in a Sentence
Recent Examples on the Web
Some clinicians have also observed low vitamin E levels in patients, though more research is needed to determine how widespread this is.
Fats
Fats are essential for nervous system repair and help maintain the myelin sheath,the fatty layer that protects nerve cells, Spechler said.
—
Mark Weinstein, MSNBC Newsweek, 27 Apr. 2025
Consistently training your brain will help boost your cognitive processes over time, because the myelin sheath—the layer of protein that coats your nerves—thickens.
—Ayana Underwood, SELF, 14 Feb. 2024
That's because, in the vast majority of spinal cord injuries, the cord is not completely severed — rather, the myelin sheath that protects the nerve cells is damaged or destroyed.
—Eliza Strickland, Discover Magazine, 12 Oct. 2010
Sensory receptors in the skin, which lack the speed-boosting insulating layer called a myelin sheath, are among the slowest, at 1 mph.
—Valerie Ross, Discover Magazine, 14 May 2011
In earlier work, Hauser and his colleagues found that the tissue damage in MS is primarily directed by B cells, which attack the myelin sheath protecting nerves.
—Lydia Denworth, Scientific American, 13 Jan. 2022
In this case, your immune system mistakenly attacks your myelin and damages the myelin sheath.
—Sara Gaynes Levy, SELF, 7 Mar. 2022
In the case of MS, the body attacks its myelin sheath, a protective covering for the nerves in the brain and spinal cord.
—Jocelyn Solis-Moreira, Health.com, 21 Jan. 2022
In the disease, inflammation damages the myelin sheath that insulates nerve cells, ultimately disrupting signals to and from the brain and causing a variety of symptoms, from numbness and pain to paralysis.
—Lydia Denworth, Scientific American, 13 Jan. 2022
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Mark Weinstein, MSNBC Newsweek, 27 Apr. 2025
Consistently training your brain will help boost your cognitive processes over time, because the myelin sheath—the layer of protein that coats your nerves—thickens.
—Ayana Underwood, SELF, 14 Feb. 2024
That's because, in the vast majority of spinal cord injuries, the cord is not completely severed — rather, the myelin sheath that protects the nerve cells is damaged or destroyed.
—Eliza Strickland, Discover Magazine, 12 Oct. 2010
Sensory receptors in the skin, which lack the speed-boosting insulating layer called a myelin sheath, are among the slowest, at 1 mph.
—Valerie Ross, Discover Magazine, 14 May 2011
In earlier work, Hauser and his colleagues found that the tissue damage in MS is primarily directed by B cells, which attack the myelin sheath protecting nerves.
—Lydia Denworth, Scientific American, 13 Jan. 2022
In this case, your immune system mistakenly attacks your myelin and damages the myelin sheath.
—Sara Gaynes Levy, SELF, 7 Mar. 2022
In the case of MS, the body attacks its myelin sheath, a protective covering for the nerves in the brain and spinal cord.
—Jocelyn Solis-Moreira, Health.com, 21 Jan. 2022
In the disease, inflammation damages the myelin sheath that insulates nerve cells, ultimately disrupting signals to and from the brain and causing a variety of symptoms, from numbness and pain to paralysis.
—Lydia Denworth, Scientific American, 13 Jan. 2022
Cite this Entry
“Myelin sheath.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/myelin%20sheath. Accessed 3 Jul. 2025.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
Share