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{{Infobox Nerve |
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Name = {{PAGENAME}} |
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Latin = nervus facialis |
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GraySubject = 202 |
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GrayPage = 901 |
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Image = Cranial nerve VII.svg |
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Caption = Cranial nerve VII |
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Image2 = Gray790.png |
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Caption2 = The nerves of the scalp, face, and side of neck. |
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Width = 300 |
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Innervates = |
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BranchFrom = |
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BranchTo = |
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MeshName = Facial+Nerve |
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MeshNumber = A08.800.800.120.250 |
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DorlandsPre = n_05 |
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DorlandsSuf = 12565770 |
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}}
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The '''facial nerve''' is the seventh (VII) of twelve paired [[cranial nerves]]. It emerges from the brainstem between the [[pons]] and the [[medulla oblongata|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]].
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==Structure==
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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]].
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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]].
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Inside one of the tight turns in the facial canal, the facial nerve forms the [[geniculate ganglion]].
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No other nerve in the body travels such a long distance through a bony canal.
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===Branches===
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====Inside the facial canal====
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* [[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]].
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* [[Nerve to stapedius]] - provides motor innervation for [[stapedius]] muscle in middle ear
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* [[Chorda tympani]] - provides parasympathetic innervation to submandibular and sublingual glands and special sensory taste fibers for the anterior 2/3 of the tongue.
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====Outside skull (distal to [[stylomastoid foramen]])====
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* [[Posterior auricular nerve]] - controls movements of some of the scalp muscles around the ear
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* Five major facial branches (in parotid gland) - from top to bottom:
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** [[Temporal branch of the facial nerve]]
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** [[Zygomatic branch of the facial nerve]]
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** [[Buccal branch of the facial nerve]]
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** [[Marginal mandibular branch of the facial nerve]]
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** [[Cervical branch of the facial nerve]]
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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", "Two Zulus Buggered [[Michael Caine]]" or "Ten Zulus Buggered My Cat"
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==Function==
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===Efferent===
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Its main function is motor control of most of the [[facial muscles|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.
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The facial also supplies [[parasympathetic nervous system|parasympathetic]] fibers to the [[submandibular gland]] and [[sublingual gland]]s 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]].
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===Afferent===
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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).
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==Location of Cell Bodies==
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The cell bodies for the facial nerve are grouped in anatomical areas called [[nucleus (neuroanatomy)|nuclei]] or [[ganglion|ganglia]]. The cell bodies for the afferent nerves are found in the 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]].
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==Pathology==
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People may suffer from [[acute facial nerve paralysis]], which is usually manifested by facial paralysis.
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[[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.
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==Testing the facial nerve==
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Voluntary facial movements, such as wrinkling the brow, showing teeth, frowning, closing the eyes tightly ([[lagophthalmos]])<ref name=Lindgren>Kliniska Färdigheter: Informationsutbytet Mellan Patient Och Läkare, LINDGREN, STEFAN, ISBN 91-44-37271-X </ref>
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, pursing the lips and puffing out the cheeks, all test the facial nerve. There should be no noticeable asymmetry.
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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.
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[[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.
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Taste can be tested on the anterior 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).
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Facial nerve can also be tested because it controls about 2/3 of the tongue. Try making your finger moist, and dipping it in some sugar, or salt (something sweet/salty) then touch your finger to the back of your tongue. See if you can taste it!
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==Additional images==
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<gallery>
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Image:Gray507.png|Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries.
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Image:Gray567.png|Dura mater and its processes exposed by removing part of the right half of the skull, and the brain.
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Image:Gray689.png|Superficial dissection of brain-stem. Ventral view.
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Image:Gray719.png|Hind- and mid-brains; postero-lateral view.
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Image:Gray780.png|The sphenopalatine ganglion and its branches.
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Image:Gray781.png|Mandibular division of the trifacial nerve.
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Image:Gray782.png|Mandibular division of trifacial nerve, seen from the middle line.
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Image:Gray788.png|Plan of the facial and intermediate nerves and their communication with other nerves.
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Image:Gray789.png |The course and connections of the facial nerve in the [[temporal bone]].
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Image:Gray792.png|Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.
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Image:Gray911.png|View of the inner wall of the tympanum (enlarged.)
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Image:Gray912.png|The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above.
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Image:Gray922.png|Position of the right bony labyrinth of the ear in the skull, viewed from above.
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Image:Gray1209.png|Left temporal bone showing surface markings for the tympanic antrum (red), transverse sinus (blue), and facial nerve (yellow).
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Image:Gray1210.png|Side of neck, showing chief surface markings.
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Image:Illu cranial nerves.jpg|Cranial nerves
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Image:Head facial nerve branches.jpg|Head facial nerve branches
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</gallery>
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==External links==
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* {{eMedicine|ent|8}}
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* [http://www.med.harvard.edu/AANLIB/cases/caseM/mr1_t/015.html position of facial nerve on MRI]
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* [http://www.neuro.wustl.edu/neuromuscular/pathol/diagrams/viianat.htm WUSTL - map]
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{{Cranial nerves}}
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[[Category:Peripheral nervous system]]
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[[Category:Cranial nerves]]
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[[de:Nervus facialis]]
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[[es:Nervio facial]]
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[[fr:Nerf facial]]
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[[lt:Veidinis nervas]]
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[[ja:顔面神経]]
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[[nl:Nervus facialis]]
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[[no:Nervus facialis]]
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[[pl:Nerw twarzowy]]
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[[pt:Nervo facial]]
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[[zh:顏面神經]]
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{{enWP|Facial nerve}}

Revision as of 17:15, 7 November 2007

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Nerve: Facial nerve
Cranial nerve VII
Cranial nerve VII
Gray790
The nerves of the scalp, face, and side of neck.
Latin nervus facialis
Gray's subject #202 901
Innervates
From
To
MeSH A08.800.800.120.250

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

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", "Two Zulus Buggered Michael Caine" or "Ten 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 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 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).

Facial nerve can also be tested because it controls about 2/3 of the tongue. Try making your finger moist, and dipping it in some sugar, or salt (something sweet/salty) then touch your finger to the back of your tongue. See if you can taste it!

Additional images

External links

Nerves of head and neck: the cranial nerves


I-IV: olfactory - optic - oculomotor - trochlear

V: trigeminal: trigeminal ganglion
V1: ophthalmic: lacrimal - frontal (supratrochlear, supraorbital) - nasociliary (long root of ciliary, long ciliary, infratrochlear, posterior ethmoidal, anterior ethmoidal) - ciliary ganglion (short ciliary)
V2: maxillary: middle meningeal - in the pterygopalatine fossa (zygomatic, zygomaticotemporal, zygomaticofacial, sphenopalatine, posterior superior alveolar)
in the infraorbital canal/infraorbital nerve (middle superior alveolar, anterior superior alveolar)
on the face (inferior palpebral, external nasal, superior labial, infraorbital plexus) - pterygopalatine ganglion (deep petrosal, nerve of pterygoid canal)
branches of distribution (palatine, nasopalatine, pharyngeal)
V3: mandibular: nervus spinosus - medial pterygoid - anterior (masseteric, deep temporal, buccal, lateral pterygoid)
posterior (auriculotemporal, lingual, inferior alveolar, mylohyoid, mental) - otic ganglion - submandibular ganglion

VI: abducens

VII: facial: nervus intermedius - geniculate - inside facial canal (greater petrosal, nerve to the stapedius, chorda tympani)
at exit from stylomastoid foramen (posterior auricular, digastric - stylohyoid)
on face (temporal, zygomatic, buccal, mandibular, cervical)

VIII: vestibulocochlear: cochlear (striae medullares, lateral lemniscus) - vestibular

IX: glossopharyngeal: fasciculus solitarius - nucleus ambiguus - ganglia (superior, petrous) - tympanic - carotid sinus

X: vagus: ganglia (jugular, nodose) - Alderman's nerve - in the neck (pharyngeal branch, superior laryngeal ext and int, recurrent laryngeal)
in the thorax (pulmonary branches, esophageal plexus) - in the abdomen (gastric plexuses, celiac plexus, gastric plexus)

XI: accessory XII: hypoglossal

de:Nervus facialis es:Nervio facial fr:Nerf facial lt:Veidinis nervas nl:Nervus facialis no:Nervus facialis pt:Nervo facial zh:顏面神經

This page uses Creative Commons Licensed content from Wikipedia (view authors).
  1. ↑ Kliniska Färdigheter: Informationsutbytet Mellan Patient Och Läkare, LINDGREN, STEFAN, ISBN 91-44-37271-X
日本語 Polski
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