Cranial Nerve #8: Vestibulocochlear Nerve

                                       

Description and Physiology

The eighth cranial nerve is the vestibulocochlear nerve.  This nerve  has several other names such as the auditory nerve, acoustic nerve, or the auditory-vestibular nerve.  The vestibulocochlear nerves runs laterally on both sides of the facial nerves.  The vestibulocochlear nerve is primarily a sensory nerve responsible for the sense of hearing and the sensation of equilibrium.  This nerve innervates the cochlea of the ear for hearing through the cochlear branch.  The vestibulcochlear nerve also innervates the vestibular branch found in the inner ear, which is responsible for balance.  Through our vestibulcochlear nerves we are able to sense sounds, gravity, and body rotation.  When this nerve has been damaged  a person may experience a false sense of movement, vertigo, or even hearing loss.

Vestibular Neuritis

Vestibular neuritis often occurs due to an inflammation of the vestibulocochlear nerve in the inner ear.  The chief symptom of vestibular neuritis is sudden vertigo, which may feel like the room is spinning or balance has been lost.  The vertigo may last several days or a few weeks.  Other symptoms associated with vestibular neuritis include vomiting and nausea.  The neuritis often comes after a viral infection and so researchers believe the neuritis may be cause by a virus.  Incorrect body movement signals are sent to the brain by the inflamed nerve and since those sensory signals do not match signals from other senses like the eyes it creates a feeling of vertigo.  Antibiotics do not treat the condition, but vestibular neuritis generally resolves itself with time.

Literature Cited

Gailard, F., & Jones, J. 2005-2010. Cranial nerves. Radiopaedia.org; [updated 2011, cited 2012 Apr 18]. Available from: http://radiopaedia.org/articles/cranial_nerves

Marshall, S., & Chalk, C. 2012. Vestibular neuritis causes, symptoms and treatment. Everyday Health; [updated 2009 Aug 18, cited 2012 Apr 25]. Available from: http://www.everydayhealth.com/health-center/vestibular-neuritis.aspx

Paulose,K. 2007-2012. 3D CT – Middle and inner ear [Internet]. Dr. Paulose – ENT, Plastic & Laser Surgeon; [cited 2012 Apr 24]. Available from: http://www.drpaulose.com/general/3d-ct-middle-and-inner-ear

Severe Deconditioning [Internet]. 2012. Physio-rehabilitation.blogspot; [updated 2012 Apr 27; cited 2012 Apr 30]. Available from: http://physio-rehabilitation.blogspot.com/

Thackery, G. 1997. The cranial nerves. Loyola University of Medical Education Network; [updated 1997 Aug 28, cited 2012 May 1]. Available from: http://www.stritch.luc.edu/lumen/MedEd/GrossAnatomy/h_n/cn/cn1/mainframe.htm

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