Vestibular nerve

Vestibular nerve
Inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid
Terminal nuclei of the vestibular nerve, with their upper connections. (Schematic.) Cochlear nerve, with its two nuclei Accessory nucleus Tuberculum acusticum Vestibular nerve Internal nucleus Nucleus of Deiters Nucleus of Bechterew Inferior or descending root of acoustic Ascending cerebellar fibers Fibers going to raphé Fibers taking an course Lemniscus Inferior sensory root of trigeminal Cerebrospinal fasciculus Raphé Fourth ventricle Inferior peduncle. Origin of striæ medullares.
Details
From	Vestibulocochlear nerve
Identifiers
Latin	Nervus vestibularis
MeSH	A08.800.800.120.910.900
TA	A14.2.01.122
FMA	53401
Anatomical terms of neuroanatomy []

The vestibular nerve is one of the two branches of the Vestibulocochlear nerve (the cochlear nerve being the other). In humans the vestibular nerve transmits sensory information transmitted by vestibular hair cells located in the two otolith organs (the utricle and the saccule) and the three semicircular canals via the vestibular ganglion. Information from the otolith organs reflects gravity and linear accelerations of the head. Information from the semicircular canals reflects rotational movement of the head. Both are necessary for the sensation of body position and gaze stability in relation to a moving environment.

Axons of the vestibular nerve synapse in the vestibular nucleus are found on the lateral floor and wall of the fourth ventricle in the pons and medulla.

It arises from bipolar cells in the vestibular ganglion, ganglion of Scarpa, which is situated in the upper part of the outer end of the internal auditory meatus.

Structure The peripheral fibers divide into three branches (some sources list two):

The primary role of the vestibular nerve is to transform vestibular information (related to balance) into an egocentric frame of reference based on the position of the head in relation to the body. The vestibular nerve dynamically updates the frame of reference of motor movement based on the orientation of the head in relation to the body. As an example, when standing upright and facing forward, if you wished to tilt your head to the right you would need to perform a slight leftward motor movement (shifting more of your weight to your left side) to maintain balance. While the head is still in motion, the response magnitude of alteration to motor coordinates is significantly reduced when compared to when the head is fixated in one position.

Due to its role in transforming motor coordinates, the vestibular nerve implicitly plays a role in maintaining stable blood pressure during movement, maintaining balance control, spatial memory and spatial navigation. The most common causes of damage to the vestibular nerve are exposure to ototoxic antibiotics, Ménière's disease, encephalitis and some rare autoimmune disorders. Typically, patients with a damaged nerve suffer from acute attacks of vertigo accompanied by nausea/vomiting, inability to maintain posture and horizontal nystagmus.