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the 3rd letter of the Roman alphabet (同)c
(music) the keynote of the scale of C major
a general-purpose programing language closely associated with the UNIX operating system

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carbonの化学記号
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/02/23 18:21:32」(JST)

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The vestibulocochlear nerve (auditory vestibular nerve), known as the eighth cranial nerve, transmits sound and equilibrium (balance) information from the inner ear to the brain.

Structure

The vestibulocochlear nerve consists mostly of bipolar neurons and splits into two large divisions: the cochlear nerve and the vestibular nerve.

The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia. Processes from the organ of Corti conduct afferent transmission to the spiral ganglia. It is the inner hair cells of the organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound. The exact mechanism by which sound is transmitted by the neurons of the cochlear nerve is uncertain; the two competing theories are place theory and temporal theory.

The vestibular nerve travels from the vestibular system of the inner ear. The vestibular ganglion houses the cell bodies of the bipolar neurons and extends processes to five sensory organs. Three of these are the cristae located in the ampullae of the semicircular canals. Hair cells of the cristae activate afferent receptors in response to rotational acceleration. The other two sensory organs supplied by the vestibular neurons are the maculae of the saccule and utricle. Hair cells of the maculae in the utricle activate afferent receptors in response to linear acceleration while hair cells of the maculae in the saccule respond to vertically directed linear force.

Development

The vestibulocochlear nerve is derived from the embryonic otic placode.

Function

This is the nerve along which the sensory cells (the hair cells) of the inner ear transmit information to the brain. It consists of the cochlear nerve, carrying information about hearing, and the vestibular nerve, carrying information about balance. It emerges from the pontomedullary junction and exits the inner skull via the internal acoustic meatus (or internal auditory meatus) in the temporal bone.

The vestibulocochlear nerve carries axons of type SSA, special somatic afferent, which carry the modalities of hearing and equilibrium.

Clinical significance

Symptoms of damage

Damage to the vestibulocochlear nerve may cause the following symptoms:

hearing loss
vertigo
false sense of motion
loss of equilibrium (in dark places)
nystagmus
motion sickness
gaze-evoked tinnitus.^[1]

Examination

History

Etymology

Some older texts call the nerve the acoustic or auditory nerve,^[2] but these terms have fallen out of widespread use because they fail to recognize the nerve's role in the vestibular system. Vestibulocochlear nerve is therefore preferred by most.

References

^ Coad, ML; Lockwood, A; Salvi, R; Burkard, R (2001). "Characteristics of patients with gaze-evoked tinnitus". Otology & Neurotology 22 (5): 650–4. PMID 11568674.
^ http://www.bartleby.com/107/203.html

Additional images

Vestibulocochlear nerve
Superficial dissection of brain-stem. Ventral view.
Dissection showing the projection fibers of the cerebellum.
Hind- and mid-brains; postero-lateral view.
Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.
Position of the right bony labyrinth of the ear in the skull, viewed from above.
Vestibulo-ocular reflex
Vestibulocochlear nerve

External links

MedEd at Loyola GrossAnatomy/h_n/cn/cn1/cn8.htm
cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (VIII)
Notes on Vestibulocochlear Nerve

UpToDate Contents

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「アミノグリコシド系抗菌薬」

Vestibulocochlear nerve
	The course and connections of the facial nerve in the temporal bone
	Inferior view of the human brain, with the cranial nerves labelled.
Details
To	Cochlear nerve, vestibular nerve
Identifiers
Latin	Nervus vestibulocochlearis
MeSH	A08.800.800.120.910
TA	A14.2.01.121
FMA	50869
	Anatomical terms of neuroanatomy [edit on Wikidata]

　　[★]

英: aminoglycoside antibiotic
関: 抗菌薬、アミノグリコシド系薬、アミノグリコシド

GOO. chapter.45

タンパク質合成阻害による抗菌薬は静菌的なのもが多いが、アミノグリコシド系抗菌薬は「殺菌的」に作用

構造

amino sugars linked to an aminocyclitol ring by glycosidic bonds (GOO.1155)
名前の通りアミノ基-NH₂を多数有しているため正電荷を帯びる

→経口吸収不良

→脳脊髄液に移行しにくい。

→腎排泄されやすい

動態

内服不可能→外来患者に使いにくい
細胞膜(内膜)の通過は膜電位ポテンシャルに依存している。ここが律速段階となる。　→　細胞内移行性悪

阻害、拮抗要素：二価陽イオン、高浸透圧、pHの低下、嫌気的条件

膿瘍など嫌気的条件、酸性の高浸透圧尿など細菌の膜電位ポテンシャルが低下する場合に薬効低下

作用機序

30Sリボソームに作用してタンパク質合成を阻害

1. 翻訳開始を阻害
2. 翻訳を停止させる
3. 誤ったアミノ酸を取り込ませる

異常蛋白が細胞膜に挿入され、膜の透過性を変えてさらにアミノグリコシド系抗菌薬の取り込みを促す

薬理作用

薬効は迅速。濃度依存的。
post-antibiotic effectがある。

抗菌薬の血漿濃度がminnimum inhibitory concentration以下になっても殺菌活性が残存。殺菌活性の残存時間は濃度依存的

抗菌スペクトル

広い

副作用

腎障害：近位尿細管の壊死変性。用量依存的
耳毒性：CN VIII障害。内耳の有毛細胞を破壊。用量依存的
神経・筋遮断作用：(稀であるが)神経筋遮断作用(およびこれによる無呼吸)を呈する。遮断作用はネオマイシンが一番強く、カナマイシン、アミカシン、ゲンタマイシン、トブラマイシンがこれに続く。通常、胸腔内、腹腔に大量投与した時に生じるが、静脈内、筋肉内、あるいは経口投与でも起こりうる。大抵の発作(神経筋接合部が遮断される発作)は麻酔薬やその他の神経筋接合部遮断薬の投与で生じる(←どういう意味？)。重症筋無力症の患者はアミノグリコシド系抗菌薬による神経筋接合部遮断作用を受けやすい。(GOO.1164)