sound and equilibrium 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 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 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

nystagmus motion sickness

gaze-evoked tinnitus. = Examination =

History = Etymology =

Some older texts call the nerve the acoustic or auditory nerve, 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. See also

Auditory system References

Additional images External links

MedEd at Loyola GrossAnatomycncn8.htm cranialnerves at The Anatomy Lesson by

Wesley Norman Notes on Vestibulocochlear Nerve