Facial nerve

Jump to navigation Jump to search

Template:Infobox Nerve

WikiDoc Resources for Facial nerve

Articles

Most recent articles on Facial nerve

Most cited articles on Facial nerve

Review articles on Facial nerve

Articles on Facial nerve in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Facial nerve

Images of Facial nerve

Photos of Facial nerve

Podcasts & MP3s on Facial nerve

Videos on Facial nerve

Evidence Based Medicine

Cochrane Collaboration on Facial nerve

Bandolier on Facial nerve

TRIP on Facial nerve

Clinical Trials

Ongoing Trials on Facial nerve at Clinical Trials.gov

Trial results on Facial nerve

Clinical Trials on Facial nerve at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Facial nerve

NICE Guidance on Facial nerve

NHS PRODIGY Guidance

FDA on Facial nerve

CDC on Facial nerve

Books

Books on Facial nerve

News

Facial nerve in the news

Be alerted to news on Facial nerve

News trends on Facial nerve

Commentary

Blogs on Facial nerve

Definitions

Definitions of Facial nerve

Patient Resources / Community

Patient resources on Facial nerve

Discussion groups on Facial nerve

Patient Handouts on Facial nerve

Directions to Hospitals Treating Facial nerve

Risk calculators and risk factors for Facial nerve

Healthcare Provider Resources

Symptoms of Facial nerve

Causes & Risk Factors for Facial nerve

Diagnostic studies for Facial nerve

Treatment of Facial nerve

Continuing Medical Education (CME)

CME Programs on Facial nerve

International

Facial nerve en Espanol

Facial nerve en Francais

Business

Facial nerve in the Marketplace

Patents on Facial nerve

Experimental / Informatics

List of terms related to Facial nerve

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


The facial nerve is the seventh (VII) of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and taste to the anterior two-thirds of the tongue. It also supplies preganglionic parasympathetic fibers to several head and neck ganglia.

Structure

The motor part of the facial nerve arises from the facial nerve nucleus in the pons while the sensory part of the facial nerve arises from the nervus intermedius.

The motor part of the facial nerve enters the petrous temporal bone into the internal auditory meatus (intimately close to the inner ear) then runs a tortuous course (including two tight turns) through the facial canal, emerges from the stylomastoid foramen and passes through the parotid gland, where it divides into five major branches. Though it passes through the parotid gland, it does not innervate the gland. This action is the responsibility of cranial nerve IX, the glossopharyngeal nerve.

Inside one of the tight turns in the facial canal, the facial nerve forms the geniculate ganglion.

No other nerve in the body travels such a long distance through a bony canal.

Branches

Inside the facial canal

  • Greater petrosal nerve - provides parasympathetic innervation to lacrimal gland, as well as special taste sensory fibers to the palate via the nerve of pterygoid canal(Vidian Nerve).
  • Nerve to stapedius - provides motor innervation for stapedius muscle in middle ear
  • Chorda tympani - provides parasympathetic innervation to submandibular and sublingual glands and special sensory taste fibers for the anterior 2/3 of the tongue.

Outside skull (distal to stylomastoid foramen)

A helpful mnemonic device for remembering the major branches are the phrases: "To Zanzibar By Motor Car", "Two Zebras Bit My Cat", "Tell Ziggy Bob Marley Called", or "Two Zulus Buggered My Cat"..

Function

Efferent

Its main function is motor control of most of the muscles of facial expression. It also innervates the posterior belly of the digastric muscle, the stylohyoid muscle, and the stapedius muscle of the middle ear. All of these muscles are striated muscles of branchiomeric origin developing from the 2nd pharyngeal arch.

The facial also supplies parasympathetic fibers to the submandibular gland and sublingual glands via chorda tympani and the submandibular ganglion. Parasympathetic innervation serves to increase the flow of saliva from these glands. It also supplies parasympathetic innervation to the nasal mucosa and the lacrimal gland via the pterygopalatine ganglion.

Afferent

In addition, it receives taste sensations from the anterior two-thirds of the tongue and sends them to the nucleus of solitary tract. The facial nerve also supplies a small amount of afferent innervation to the oropharynx above the palatine tonsil. There is also a small amount of cutaneous sensation carried by the nervus intermedius from the skin in and around the auricle (earlobe).

Location of Cell Bodies

The cell bodies for the facial nerve are grouped in anatomical areas called nuclei or ganglia. The cell bodies for the afferent nerves are found in the geniculate ganglion for both taste and general afferent sensation. The cell bodies for muscular efferent nerves are found in the facial motor nucleus whereas the cell bodies for the parasympathetic efferent nerves are found in the superior salivatory nucleus.

Pathology

People may suffer from acute facial nerve paralysis, which is usually manifested by facial paralysis. Bell's palsy is one type of idiopathic acute facial nerve paralysis, which is more accurately described as a multiple cranial nerve ganglionitis that involves the facial nerve, and most likely results from viral infection and also sometimes as a result of Lyme disease.

Testing the facial nerve

Voluntary facial movements, such as wrinkling the brow, showing teeth, frowning, closing the eyes tightly (lagophthalmos)[1] , pursing the lips and puffing out the cheeks, all test the facial nerve. There should be no noticeable asymmetry.

In an upper motor neuron lesion, called central seven, only the lower part of the face on the opposite side will be affected, due to the bilateral control to the upper facial muscles.

Lower motor neuron lesions can result in Bell's palsy, manifested as both upper and lower facial weakness on the same side of the lesion.

Taste can be tested on the anterior 2/3 of the tongue. This can be tested with a swab dipped in a flavoured solution, or with electronic stimulation (similar to putting your tongue on a battery).

Additional images

References

  1. Kliniska Färdigheter: Informationsutbytet Mellan Patient Och Läkare, LINDGREN, STEFAN, ISBN 91-44-37271-X

External links

Template:Cranial nerves

de:Nervus facialis lt:Veidinis nervas nl:Nervus facialis no:Nervus facialis fi:Kasvohermo sv:Ansiktsnerven

Template:Jb1 Template:WH Template:WS