MEDULLARY SHEATH Meaning and
Definition
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The medullary sheath, also known as the myelin sheath, is a protective covering surrounding the nerves of the central and peripheral nervous systems. This sheath is formed by specialized cells called Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. It is an essential component of the nervous system, responsible for insulating and protecting nerve fibers by forming a fatty layer around them.
The primary function of the medullary sheath is to facilitate the conduction of nerve impulses along the nerve fibers. It acts as an electrical insulator, preventing the leakage of electric signals and allowing them to travel more efficiently. The myelin sheath also increases the speed at which nerve impulses are transmitted by aiding in the process of saltatory conduction, where the impulses jump between nodes of Ranvier along the nerve fiber.
The medullary sheath has a characteristic whitish appearance, hence its name "white matter." It is primarily composed of lipids, specifically myelin, which gives it its insulating properties. The thickness of the sheath can vary depending on the size and function of the nerve fibers it surrounds.
Disorders that affect the medullary sheath, such as multiple sclerosis, can result in impaired nerve conduction. Damage to the sheath can cause various neurological symptoms, including loss of sensation, muscle weakness, and coordination difficulties.
In summary, the medullary sheath is the protective fatty layer surrounding nerve fibers in the nervous system. Its role is to insulate and enhance the conduction of nerve impulses, allowing efficient communication within the body.
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(1) M. substance; (2) in botany, the sheath of protoxylem surrounding the pith of a stem.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
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In a thin layer of vascular tissue which surrounds the pith in exogenous stems.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
Common Misspellings for MEDULLARY SHEATH
- nedullary sheath
- kedullary sheath
- jedullary sheath
- mwdullary sheath
- msdullary sheath
- mddullary sheath
- mrdullary sheath
- m4dullary sheath
- m3dullary sheath
- mesullary sheath
- mexullary sheath
- mecullary sheath
- mefullary sheath
- merullary sheath
- meeullary sheath
- medyllary sheath
- medhllary sheath
- medjllary sheath
- medillary sheath
Etymology of MEDULLARY SHEATH
The word "medullary sheath" has its origins in Latin and Greek.
The term "medullary" comes from the Latin word "medulla", which means "marrow" or "core". It refers to the innermost part of a structure or substance. In the context of the nervous system, it specifically refers to the inner part of certain nerves.
The word "sheath" comes from the Old English word "sceath", which means a protective covering or case. It is derived from the Proto-Germanic word "skēthō" and is also related to the Old Norse word "skjǫdr" and the Old High German word "scato".
Similar spelling word for MEDULLARY SHEATH
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