Vestibular nerve

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Nerve: Vestibular nerve
Vestibular system's semicircular canal- a cross-section.jpg
Inner ear illustration showing semicircular canal, hair cells, ampulla, cupula, vestibular nerve, & fluid
Gray761.png
Terminal nuclei of the vestibular nerve, with their upper connections. (Schematic.)
1. Cochlear nerve, with its two nuclei.
2. Accessory nucleus.
3. Tuberculum acusticum.
4. Vestibular nerve.
5. Internal nucleus.
6. Nucleus of Deiters.
7. Nucleus of Bechterew.
8. Inferior or descending root of acoustic.
9. Ascending cerebellar fibers.
10. Fibers going to raphé.
11. Fibers taking an oblique course.
12. Lemniscus.
13. Inferior sensory root of trigeminal.
14. Cerebrospinal fasciculus.
15. Raphé.
16. Fourth ventricle.
17. Inferior peduncle. Origin of striæ medullares.
Latin Nervus vestibularis
Gray's p.906
From Vestibulocochlear nerve
MeSH Vestibular+Nerve

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 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):[1]

Function[edit]

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.[2] 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.[2]

Clinical significance[edit]

Damage[edit]

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.[3] The most common causes of damage to the vestibular nerve are exposure to ototoxic antibiotics, Ménière's disease, encephalitis and some rare autoimmune disorders.[3] Typically, patients with a damaged nerve suffer from acute attacks of vertigo accompanied by nausea/vomiting, inability to maintain posture and horizontal nystagmus.[4]

Rehabilitation[edit]

Rapid compensation to damage of the vestibular nerve occurs within seven to ten days of receiving the damage. A small percentage of patients with damage to the vestibular nerve experience recurrent symptoms.[4] These patients have not been able to undergo vestibular compensation and are left with long-term attacks of vertigo. By administering betahistine to the damaged nerve over a long period of time, the process of vestibular compensation can be accelerated to alleviate symptoms. Patients can also learn strategies to recover their balance through physical therapy.[5]

See also[edit]

This article uses anatomical terminology; for an overview, see anatomical terminology.

Additional images[edit]

References[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.

  1. ^ eMedicine - Anatomy of the Vestibular System : Article by Steve C Lee
  2. ^ a b Osler, Callum; Reynolds, Raymond (26 August 2012). Dynamic transformation of vestibular signals for orientation (Exp Brain Res). doi:10.1007/s00221-012-3250-1. 
  3. ^ a b McCall, Andrew; Yates, Bill (27 December 2011). "Compensation following bilateral vestibular damage". frontiers in NEUROLOGY. doi:10.3389/fneur.2011.00088. Retrieved 11/10/12. 
  4. ^ a b Fundakowski, Christopher; Joshua Anderson; Simon Angeli (2012). "Cross-Sectional Vestibular Nerve Analysis in Vestibular Neuritis". Annals of Otology, Rhinology, and Laryngology. 121(7): 466–470. 
  5. ^ Georgescu, Madalina; Sorina Stoian, Carmen Mogoanta (27 August 2012). "Vestibulary rehabilitation – election treatment method for compensating vestibular impairment". Romanian Journal of Morphology & Embryology. 53(3): 651–656. 

External links[edit]