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'''Neurilemma'''
{{Short description|The outermost layer of the nerve fiber in the peripheral nervous system}}


The '''Neurilemma''' also known as the '''neuron sheath''' or '''Schwann cell membrane''' is the outermost layer of [[nerve fibers]] in the [[peripheral nervous system]]. It is formed by [[Schwann cells]] and plays a crucial role in the regeneration of damaged nerve fibers.
==Neurilemma==
The '''neurilemma''', also known as the '''sheath of Schwann''', is the outermost layer of the [[myelinated]] or [[unmyelinated]] [[nerve fibers]] in the [[peripheral nervous system]] (PNS). It is formed by [[Schwann cells]], which are a type of [[glial cell]] that play a crucial role in the maintenance and regeneration of [[peripheral nerves]].


==Structure==
==Structure==
The neurilemma is a thin, delicate membrane that envelops the axon of a nerve cell. In myelinated nerve fibers, the neurilemma is the outermost layer of the [[myelin sheath]], which is composed of multiple layers of Schwann cell membrane wrapped around the axon. In unmyelinated fibers, the neurilemma still surrounds the axon, but without the multiple layers of myelin.


The neurilemma is composed of [[Schwann cells]], which wrap around the [[axon]] of the nerve fiber. Each Schwann cell forms a single segment of the neurilemma, and multiple Schwann cells are aligned along the length of the axon to form the complete neurilemma.
[[File:Neuron with Schwann cell.png|thumb|right|Diagram of a neuron with a Schwann cell forming the myelin sheath and neurilemma.]]


==Function==
==Function==
The primary function of the neurilemma is to protect and insulate nerve fibers, facilitating the rapid transmission of [[nerve impulses]] along the axon. Additionally, the neurilemma plays a vital role in the regeneration of damaged nerve fibers. When a peripheral nerve is injured, the neurilemma provides a pathway for the regrowth of the axon, allowing for the potential recovery of nerve function.


The primary function of the neurilemma is to support nerve fiber regeneration. When a nerve fiber is damaged, the neurilemma helps to guide the growth of new axons, allowing the nerve to regain its function. This is particularly important in the [[peripheral nervous system]], where nerve damage is more common and the need for regeneration is greater.
==Regeneration==
Unlike the [[central nervous system]] (CNS), where nerve regeneration is limited, the PNS has a greater capacity for repair and regeneration, largely due to the presence of the neurilemma. Schwann cells within the neurilemma secrete growth factors and form a regeneration tube that guides the regrowing axon to its target.


==Clinical significance==
==Clinical Significance==
 
Damage to the neurilemma can result in impaired nerve function and delayed or incomplete nerve regeneration. Conditions such as [[neuropathy]] and [[nerve compression syndromes]] can affect the integrity of the neurilemma, leading to symptoms such as pain, numbness, and muscle weakness.
Damage to the neurilemma can lead to a variety of [[neurological disorders]], including [[peripheral neuropathy]] and [[Charcot-Marie-Tooth disease]]. In addition, certain types of [[cancer]], such as [[neurofibromatosis]], can cause tumors to form on the neurilemma.
 
==See also==


==Related pages==
* [[Schwann cell]]
* [[Myelin sheath]]
* [[Myelin sheath]]
* [[Peripheral nervous system]]
* [[Nerve regeneration]]
* [[Nerve regeneration]]
* [[Schwann cell]]
* [[Glial cell]]
 
==References==
 
<references />
 
[[Category:Neurology]]
[[Category:Anatomy]]
[[Category:Cell biology]]


{{stub}}
[[Category:Neuroanatomy]]
<gallery>
[[Category:Peripheral nervous system]]
File:Neurilemma Gray631.png|Neurilemma
File:Myelin_sheath_(1).svg|Myelin sheath
</gallery>

Revision as of 17:44, 18 February 2025

The outermost layer of the nerve fiber in the peripheral nervous system


Neurilemma

The neurilemma, also known as the sheath of Schwann, is the outermost layer of the myelinated or unmyelinated nerve fibers in the peripheral nervous system (PNS). It is formed by Schwann cells, which are a type of glial cell that play a crucial role in the maintenance and regeneration of peripheral nerves.

Structure

The neurilemma is a thin, delicate membrane that envelops the axon of a nerve cell. In myelinated nerve fibers, the neurilemma is the outermost layer of the myelin sheath, which is composed of multiple layers of Schwann cell membrane wrapped around the axon. In unmyelinated fibers, the neurilemma still surrounds the axon, but without the multiple layers of myelin.

File:Neuron with Schwann cell.png
Diagram of a neuron with a Schwann cell forming the myelin sheath and neurilemma.

Function

The primary function of the neurilemma is to protect and insulate nerve fibers, facilitating the rapid transmission of nerve impulses along the axon. Additionally, the neurilemma plays a vital role in the regeneration of damaged nerve fibers. When a peripheral nerve is injured, the neurilemma provides a pathway for the regrowth of the axon, allowing for the potential recovery of nerve function.

Regeneration

Unlike the central nervous system (CNS), where nerve regeneration is limited, the PNS has a greater capacity for repair and regeneration, largely due to the presence of the neurilemma. Schwann cells within the neurilemma secrete growth factors and form a regeneration tube that guides the regrowing axon to its target.

Clinical Significance

Damage to the neurilemma can result in impaired nerve function and delayed or incomplete nerve regeneration. Conditions such as neuropathy and nerve compression syndromes can affect the integrity of the neurilemma, leading to symptoms such as pain, numbness, and muscle weakness.

Related pages