関: cerebellar mossy fiber、nerve fibre

WordNet

any bundle of nerve fibers running to various organs and tissues of the body (同)nervus
tell a relatively insignificant lie; "Fibbing is not acceptable, even if you dont call it lying"
a trivial lie; "he told a fib about eating his spinach"; "how can I stop my child from telling stories?" (同)story, tale, tarradiddle, taradiddle
a slender and greatly elongated substance capable of being spun into yarn (同)fibre
a leatherlike material made by compressing layers of paper or cloth (同)fibre, vulcanized fiber
any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber) (同)fibre
control of your emotions; "this kind of tension is not good for my nerves"

PrepTutorEJDIC

〈C〉『神経』 / 〈C〉《複数形で》『神経過敏』,いらだち / 〈U〉『勇気』,度胸(courage) / 〈U〉《時にa ~》厚かましさ,ずぶとさ;無礼 / 〈C〉葉脈;(昆虫の)翅脈(しみゃく) / 〈人,特に自分〉‘に'力を与える,‘を'元気づける
(ささいな,罪のない)うそ / 軽いうそをつく

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/07/27 23:29:06」(JST)

wiki en

A nerve fiber is a threadlike extension of a nerve cell and consists of an axon and (in some cases) a myelin sheath. There are nerve fibers in the central nervous system and peripheral nervous system. In the central nervous system (CNS), myelin is produced by oligodendroglia cells. Schwann cells form myelin in the peripheral nervous system (PNS). Schwann cells can also make a thin covering for an axon which does not consist of myelin (in the PNS). A peripheral nerve fiber consists of an axon, myelin sheath, Schwann cells and its endoneurium. There are no endoneurium and Schwann cells in the central nervous system.

1 Central nerve fibers
- 1.1 Descending nerve fibers (Upper motor neurons)
- 1.2 Ascending nerve fibers
2 Peripheral nerve fiber types
3 Components of peripheral nerve fiber
4 Classification of peripheral nerve fibers
- 4.1 A group
- 4.2 B group
- 4.3 C group
5 Motor fibers of the A group
6 Sensory fibers of the A group
7 Regeneration of peripheral nerve fibers
8 See also
9 References
10 Further reading

Central nerve fibers

In the central nervous system, nerve fibers differ in terms of size, conduction velocity, and presence or lack of myelin. For example, the olfactory nerve fibers are short and without myelin, but the optic nerve fibers are myelinated (the olfactory and optic nerves are considered as a parts of the CNS, while other cranial nerves are a component of the PNS). A bundle of nerve fibers constitutes a tract in the central nervous system. The pyramidal tract and extrapyramidal tracts have long nerve fibers that descend from the brain to the spinal cord. These fibers have an important role in motor control, and are known as descending tracts. There are other bundles of nerve fibers in the CNS that are called ascending tracts.These carry sensory information from the periphery to the different areas of the brain (such as the cerebral cortex, cerebellum, and brain stem).

Descending nerve fibers (Upper motor neurons)

Pyramidal system
- Corticospinal tract (or Pyramidal tract)
- Corticobulbar tract
Extrapyramidal tracts
- Vestibulospinal tract
- Reticulospinal tract
- Tectospinal tract
- Rubrospinal tract
- Olivospinal tract
Descending autonomic fibers
- Hypothalamobulbar fibers
- Hypothalamospinal fibers

Ascending nerve fibers

Spinothalamic tract
- Anterior spinothalamic tract
- Lateral spinothalamic tract
Fasciculus cuneatus
Fasciculus gracilis
Spinoreticular tract
Spinotectal tract
Spinocerebellar tract
- Posterior spinocerebellar tract
- Anterior spinocerebellar tract
- Cuneocerebellar tract
- Rostral spinocerebellar tract
Spinocervical tract

Peripheral nerve fiber types

A nerve may be sensory, motor or sensory-motor (mixed). There are three types of nerve fibers in a mixed nerve that include:

Sensory nerve fibers (afferent fibers)
Motor nerve fibers (efferent fibers)
Autonomic nerve fibers (autonomic fibers)

Components of peripheral nerve fiber

Each peripheral nerve fiber contains:

An axon (or a long dendrite of sensory fiber that also is known as an axon)
Axolemma
Myelin sheath (not always)
Schwann's sheath (neurolemma)
Endoneurium

Classification of peripheral nerve fibers

There are three types of peripheral nerve fibers based on their diameter:

A group
B group
C group

A group

Fibers of the A group have a large diameter, are myelinated, and have the highest conduction velocity of all the nerves in the body.

The A group consists of four types of nerve fibers:

A alpha fibers (afferent or efferent fibers)
A beta fibers (afferent or efferent fibers)
A gamma fibers (efferent fibers)
A delta fibers (afferent fibers)

B group

Nerve fibers in this group are myelinated with a small diameter. Generally, they are the preganglionic fibers of the autonomic nervous system and have a low conduction velocity.

C group

The C group fibers are unmyelinated and as the B group fibers have a small diameter and low conduction velocity. These fibers include:

Postganglionic fibers in the autonomic nervous system (ANS)
Nerve fibers at the dorsal roots (IV fiber). These fibers carry the following sensory information:
- Nociception (pain)
- Temperature
- Touch
- Pressure
- Itch

Motor fibers of the A group

A alpha fibers

Characteristics:
- High conduction velocity
- By alpha motor neuron for muscle contraction.
- Alpha motor neurons innervate extrafusal muscle fibers (slow and fast fibers)

A beta fibers

Characteristics:
- By beta motor neuron for muscle spindle fibers contraction.
- Beta motor neurons innervate intrafusal muscle fibers of muscle spindles (nuclear bag and nuclear chain fibers), with collaterals to extrafusal muscle fibers.

A gamma fibers

Characteristics:
- By gamma motor neuron for muscle spindle fibers contraction.
- Gamma motor neurons innervate intrafusal muscle fibers of muscle spindles (nuclear bag and nuclear chain fibers).

Sensory fibers of the A group

A alpha fibers (Ia fiber or Ib fibers)

Characteristics:
- High conduction velocity
- Ia fibers are related to muscle spindle primary endings (muscle sense)
- Ib fibers are related to golgi tendon organs (muscle sense)

A beta fibers (II fibers)

II fibers carry sensory information related to muscle spindle secondary endings, touch, and kinesthesia.

A delta fibers (III fibers)

III fibers carry sensory information related to pain and cold temperature.

Regeneration of peripheral nerve fibers

Nerves can be easily damaged in a traumatic event due to their sometimes vulnerable positions in the body. However, if a nerve is damaged, it does have the ability to regenerate if its soma and a small portion of the neurilemma remain. The nerve begins the process by destroying the nerve distal to the site of injury allowing Schwann cells, basal lamina, and the neurilemma near the injury to begin producing a regeneration tube. Nerve growth factors are produced causing many nerve sprouts to bud. When one of the growth processes finds the regeneration tube, it begins to grow rapidly towards its original destination guided the entire time by the regeneration tube. Nerve regeneration is very slow and can take up to several months to complete. While this process does repair some nerves, there will still be some functional deficit as the repairs are not perfect.^[1]

References

^ Burnett & Zager, Mark & Eric. "Pathophysiology of Peripheral Nerve Injury: A Brief Review: Nerve Regeneration". Medscape Article. Medscape. Retrieved 2011-10-26.

UpToDate Contents

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1. 神経伝導検査の概要 overview of nerve conduction studies
2. 下肢末梢神経症候群の概要 overview of lower extremity peripheral nerve syndromes
3. 上肢末梢神経症候群の概要 overview of upper extremity peripheral nerve syndromes
4. 末梢神経障害の評価のための皮膚生検 skin biopsy for the evaluation of peripheral nerve disease
5. 神経筋接合部の電気診断学的評価 electrodiagnostic evaluation of the neuromuscular junction

English Journal

A Low-Power ASIC Signal Processor for a Vestibular Prosthesis.

Toreyin H, Bhatti PT.
IEEE transactions on biomedical circuits and systems.IEEE Trans Biomed Circuits Syst.2016 Jun;10(3):768-78. doi: 10.1109/TBCAS.2015.2495341. Epub 2016 Jan 18.
A low-power ASIC signal processor for a vestibular prosthesis (VP) is reported. Fabricated with TI 0.35 μm CMOS technology and designed to interface with implanted inertial sensors, the digitally assisted analog signal processor operates extensively in the CMOS subthreshold region. During its opera
PMID 26800546

Nerve Growth Factor Promotes Angiogenesis and Skeletal Muscle Fiber Remodeling in a Murine Model of Hindlimb Ischemia.

Diao YP, Cui FK, Yan S, Chen ZG, Lian LS, Guo LL, Li YJ1.
Chinese medical journal.Chin Med J (Engl).2016 5th Feb;129(3):313-319. doi: 10.4103/0366-6999.174496.
BACKGROUND: Therapeutic angiogenesis has been shown to promote blood vessel growth and improve tissue perfusion. Nerve growth factor (NGF) has been reported to play an important role in both physiological and pathological angiogenesis. This study aimed to investigate the effects of NGF on angiogenes
PMID 26831234

A novel histochemical method for the visualization of thrombin activity in the nervous system.

Bushi D1, Gera O2, Kostenich G3, Shavit-Stein E4, Weiss R5, Chapman J6, Tanne D7.
Neuroscience.Neuroscience.2016 Apr 21;320:93-104. doi: 10.1016/j.neuroscience.2016.01.065. Epub 2016 Feb 4.
Although thrombin has an important role in both central and peripheral nerve diseases, characterization of the anatomical distribution of its proteolytic activity has been limited by available methods. This study presents the development, challenges, validation and implementation of a novel histoche
PMID 26851772

Japanese Journal

Differentiation by imaging of superior segmental optic hypoplasia and normal-tension glaucoma with inferior visual field defects only

Yamada Miki,Ohkubo Shinji,Higashide Tomomi [他],Nitta Koji,Takeda Hisashi,Sugiyama Kazuhisa
Japanese Journal of Ophthalmology 57(1), 25-33, 2013-01-00
… Results: Retinal nerve fiber layer thickness (RNFLT) based on OCT measurements was significantly reduced (thinner) in the superior to superonasal sectors and significantly greater (thicker) in the inferotemporal sector in the SSOH group than in the NTG group. …
NAID 40019546289

The nerves to the plantaris muscle and a bipennate part of the soleus muscle

Okamoto Keishi,Wakebe Tetsuaki,Saiki Kazunobu,Tsurumoto Toshiyuki
Anatomical Science International 88(1), 17-24, 2013-01-00
… We performed nerve fiber analysis of the nerve to the plantaris muscle in ten cases. … Macroscopically, the nerve to the plantaris muscle has a tendency to branch off from the tibial nerve itself independent of the nerves to the gastrocnemius and soleus muscles (the triceps surae muscle). …
NAID 120005230615

水頭症の内視鏡手術に必要な解剖と知識

西山健一,藤井幸彦
Japanese Journal of Neurosurgery 22(5), 349-356, 2013
本稿では, 水頭症および関連する嚢胞性疾患に対して髄液路を作成する脳室鏡手術を提示し, 必要な解剖と知識を概説した. ここで術式は "脳室-脳槽短絡術" と "脳室内閉塞機転の解除" に大別される. 鏡視下で目印となる脳室内構造の把握に加えて, 前者では脳槽の構築と内部血管の, 後者では脳室壁直下の神経路と神経核の理解が必須である. "Third ventriculostomy" では, 両側乳 …
NAID 130003379619

Related Pictures

★リンクテーブル★

リンク元	「神経線維」「cerebellar mossy fiber」
拡張検索	「dopaminergic nerve fiber」「vestibular primary afferent nerve fiber」
関連記事	「nerve」

「神経線維」

Nerve fiber
	Micrograph showing nerve fibers in a nerve root. HPS stain.
Details
Identifiers
Latin	neurofibra
MeSH	Nerve+Fibers
Code	TA A14.0.00.001
	Anatomical terminology [edit on Wikidata]