Tikrit University – College of Dentistry Dr.Ban I.S. head & neck Anatomy 2nd y.

cden.tu.edu.iq 1

Lec[6]FacialNerve:

The facial nerve has a motor root and a sensory root (nervus

intermedius). The nerve emerges from the brain between the pons and

the medulla oblongata. The roots pass laterally in the posterior cranial

fossa with the vestibulocochlear nerve and enter the internal acoustic

meatusinthepetrouspartofthetemporalbone.Nearthemiddleearthe

nervemakesasharpposteriorbend,whichisenlargedbythecellbodies

of theafferent (taste) fibers to form thegeniculateganglion. Fromhere

thenerverunsbackinthefacialcanalinthemedialwallofthemiddleear.

Itnowcurvesdownwardsbehindthemiddleear,andpassesvertically

downinthefacialcanal.Aftersheddingallthenervusintermediusfibers,

thenerveemergesfromthestylomastoidforamenasamotornerveand

passesthroughtheparotidglandtoitsdistribution.

Tikrit University – College of Dentistry Dr.Ban I.S. head & neck Anatomy 2nd y.

cden.tu.edu.iq 2

ImportantBranchesoftheFacialNerve

1-Greaterpetrosalnervearisesfromthenerveatthegeniculateganglion.

It contains preganglionic parasympathetic fibers that synapse in the

pterygopalatine ganglion. The postganglionic fibers are secretomotor to

thelacrimalglandandtheglandsofthenoseandthepalate.

Thegreaterpetrosalnerve,consistingofnervusintermediusfibers,leaves

theganglionandtravelsforwardsandmediallyata45°slantthroughthe

petrousbone. Itemergesfromtheanterosuperiorsurfaceofthepetrous

boneandrunsforwards.Thenervepassesbeneaththetrigeminalganglion

andreachestheforamenlacerum,whereitisjoinedbythedeeppetrosal

nervefromthesympatheticplexusontheinternalcarotidartery.Thetwo

unite and pass forwards through thepterygoid canal. This nerve of the

pterygoidcanal[vidiannerve]emergesintothepterygopalatinefossaand

enters the pterygopalatine ganglion. Here the parasympathetic fibers

relay.

Tikrit University – College of Dentistry Dr.Ban I.S. head & neck Anatomy 2nd y.

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Tastefibersfromthesoftpalateandsympatheticfiberspassstraight

through the ganglion. Postganglionic secretomotor fibers are distributed

with the branches of the ganglion to the nose, paranasal sinuses, hard

andsoftpalates,andnasopharynx.Lacrimatorypostganglionicfibersjoin

themaxillarynerveandentertheorbitinitszygomaticbranch.

2-Nervetostapediussuppliesthestapediusmuscleinthemiddleear.The

nervetostapedius isgivenoff inthefacialcanalandreachesthemuscle

byaminutecanaliculus.

Tikrit University – College of Dentistry Dr.Ban I.S. head & neck Anatomy 2nd y.

cden.tu.edu.iq 4

3-Chorda tympani arises from the facial nerve in the facial canal in the

posteriorwallofthemiddleear.Itrunsforwardoverthemedialsurfaceof

the upper part of the tympanic membrane and leaves the middle ear

throughthepetrotympanicfissure,thusenteringtheinfratemporalfossa

and joining the lingualnerve.Thechorda tympanicontainspreganglionic

parasympathetic secretomotor fibers to the submandibular and the

sublingual salivary glands. It also contains taste fibers from the anterior

twothirdsofthetongue.

Tikrit University – College of Dentistry Dr.Ban I.S. head & neck Anatomy 2nd y.

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By the lingualnerve its taste fibers are taken to theanteriorpartof the

tongue. Its secretomotor fibers relay in the submandibular ganglion for

thesubmandibulargland,sublingualgland.

4-muscularbranchesgivenoffbythefacialnerveasitemergesfromthe

stylomastoidforamen.Theyinnervatetheposteriorbellyofthedigastric,

andthestylohyoidmuscles.

5-Posterior auricular branch: muscular branch supplies, occipitalis,

auricularisposteriorandauricularissuperior.

6-Five terminal branches to themuscles of facial expression:These are

the temporal, the zygomatic, thebuccal, themarginalmandibular, and

thecervicalbranches.

Thefacialnervethuscontrolsfacialexpression,salivation,andlacrimation

andisapathwayfortastesensationfromtheanteriorpartofthetongue.