Facialis Ideg Nagyon Jo

8/13/2019 Facialis Ideg Nagyon Jo

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The Facial Nerve:Functional Components and

Anatomy


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Brief overview of cranial nerve functional components

The 12 cranial nerves participate in a total of seven neural functions. Each ofthese seven functions is designated by a three letter acronym.

The first letter is either G (General) or S (Special). General refers to primitive and/or external structures of the body. Special refers to senses unique to the head (taste, olfaction, hearing, vision, and

balance) and to muscles of branchial arch derivatives.

The second letter is either S (Somatic) or V (Visceral). Somatic refers to non-visceral structures including skin, muscles, tendons, joints,

retina (vision), basilar membrane (hearing), and utricle/saccula (balance). Visceral refers to organs of the body cavity, smooth muscle, vessels, and glands.

The third letter is either A (Afferent) or E (Efferent). Afferent refers to flow of neural information toward the brain (sensation) Efferent refers to flow of neural information toward the periphery (motor).

Knowledge of the functional components and the deficits that follow damageto each provides the basis of the thorough neurological exam.


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The Seven Functional Components GSA General Somatic Afferent

Touch, temperature, and pain from non-visceral structures

GSE General Somatic Efferent Motor to skeletal muscle

GVA General Visceral Afferent Touch (distention), temperature, and pain from the viscera

GVE General Visceral Efferent Motor to viscera, smooth muscle, and glands

SSA Special Somatic Afferent Vision, hearing, and balance

SSE Doesnt exist SVA Special Visceral Afferent

Taste and olfaction SVE Special Visceral Efferent

Motor to muscles derived from the branchial arches


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The remainder of this tutorial focuses on thefunctional nerve components contained within the

facial nerve:SVEGVASVAGVEGSA

These components, either alone or in combination, make up thefacial nerve and its branches. An understanding of thesecomponents can serve as a template for understanding the other

functional components. In addition, an understanding of the facialnerve and its components can be applied in clinical situations tohelp localize a patients defect.


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Functional Components Within Branches of theFacial Nerve:

Greater Superficial Petrosal Nerve (GSPN) GVA , GVE , SVA

Stapedial Nerve

SVE Chorda Tympani Nerve

GVE , SVA

Posterior Auricular Nerve

SVE, GSA Facial Nerve (terminal branch)

SVE


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Anatomy of Facial Nerve Branches The facial nerve exits the posterior cranial fossa (PCF) at the internal

acoustic meatus. Within the internal acoustic meatus the facial nerve enters the facial

canal. The first branch of the facial nerve, the greater superficial petrosal nerve

(GSPN) branches from the geniculate ganglion within the genu of thefacial canal and enters the middle cranial fossa by way of the hiatus ofthe canal for the GSPN.

The second branch of the facial nerve, the stapedial nerve, branchesfrom the descending portion of the facial nerve and enters the middleear.

The third branch of the facial nerve, the chorda tympani nerve, branchesfrom the descending portion of the facial nerve and enters the middleear. Within the middle ear the chorda tympani nerve crosses the medialsurface of the tympanic membrane. It then passes through thepetrotympanic fissure to enter the infratemporal fossa.

The descending portion of the facial nerve continues into the parotidregion by way of the stylomastoid foramen.


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Overview of FacialNerve anatomy inthe skull

Lacerate foramen

Facialcanal

Internal AcousticMeatus

StylomastoidForamen

Hiatus of canal of greatersuperficial petrosal nerve

Pterygoidcanal

GreatersuperficialPetrosalnerve(GSPN)

Petrotympanicfissure

Greater andlesser palatinecanals

Chorda tympani nerve

Facial nerve

Facial nerve

PosteriorCranialFossa (PCF)

Inferior Orbital Fissure

The facial nerve exits the posterior cranial fossa (PCF) at the internal acousticmeatus .

Click here to start Animation

Posteriorauricular N.


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Lacerate foramen

Facialcanal


StylomastoidForamen


Pterygoidcanal




Chorda tympani

Facial nerve

Facial nerve

PosteriorCranialFossa



Within the internal acoustic meatus the facial nerve enters the facial canal.



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Lacerate foramen


StylomastoidForamen


Pterygoidcanal




Chorda tympani

Facial nerve

Facial nerve




The first branch of the facial nerve, the greater superficial petrosal nerve (GSPN) branchesfrom the geniculate ganglion within the genu of the facial canal and entersthe middle cranial fossa (MCF) by way of the hiatus of the canal for the GSPN.

Geniculate ganglion

Facialcanal

MCF


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Lacerate foramen

Facialcanal


StylomastoidForamen


Pterygoidcanal



Chorda tympani

Facial nerve

Facial nerve




The second branch of the facial nerve, the stapedial nerve, branches from thedescending portion of the facial nerve and enters the middle ear.

Stapedial N. Petrotympanicfissure



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Lacerate foramen

Facialcanal


StylomastoidForamen


Pterygoidcanal




Chorda tympani N.

Facial nerve

Facial nerve




The third branch of the facial nerve, the chorda tympani nerve, branches from thedescending portion of the facial nerve and enters the middle ear. Within the middle earthe chorda tympani nerve crosses the medial surface of the tympanic membrane. It thenpasses through the petrotympanic fissure to enter the infratemporal fossa.

Infratemporalfossa


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Lacerate foramen

Facialcanal


StylomastoidForamen


Pterygoidcanal




Chorda tympani

Facial nerve

Facial nerve




The descending portion of the facial nerve exits the facial canal at thestylomastoid foramen and continues into the parotid region

ParotidregionPosterior

auricular N.


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Functional components of theFacial Nerve (CN VII)

SVE (Special Visceral Efferent) Motor tostriated muscles derived from the 2 nd branchialarch.

GVA (General Visceral Afferent) Sensoryfrom visceral touch, temperature, and pain.

SVA (Special Visceral Afferent) Taste GVE (General Visceral Efferent) Autonomic

innervation to mucosal, lacrimal, and salivary

glands. GSA (General Somatic Afferent) Sensory

from somatic touch, temperature, and pain.

1.

2.

3.

4.

5.

Click on numbers for functional components


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SVE Component of theFacial Nerve

The next 11 slides demonstrate innervation tomuscles derived from the 2 nd branchial arch:

1. Stapedius muscle -- dampens movement of theossicles (inserts on stapes of middle ear)

2. Posterior auricular muscle -- posterior movementof pinna

3. Stylohyoid muscle -- elevates hyoid bone4. Posterior belly of digastric -- elevates hyoid

bone, depresses mandible5. Muscles of facial expression -- blinking, smiling,frowning, facial movements

Click here to start Animation of SVE component


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\Stapedius muscle dampens movement of the

ossicles protecting the inner ear fromdamage from loud noises

SVE


1. The Stapedius muscle dampens movement of the ossicles


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2. The Posterior Auricular nerve innervates the posteriorauricular muscle, pulling the pinna posteriorly.


SVEcomponent ofposteriorauricular nerve

Posterior auricularmuscle pulls thepinna posteriorly

SVE


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Stylohyoidmuscle elevatesthe hyoid bone.

Through the internal Acoustic meatus

Through thestylomastoidforamen

3. The Stylohyoid muscle elevates the hyoid bone


Stylohyoid branch offacial nerveinnervates stylohyoidmuscle

SVE


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Through thestylomastoidforamen

4. The Posterior belly of digastric muscle elevates the hyoid bone


Posterior belly ofdigastric branch offacial nerveinnervates posteriorbelly of digastricmuscle.

Posterior belly ofdigastric muscleelevates thehyoid bone

SVEThrough the internalacoustic meatus


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5. The next six slides demonstrate SVE innervation tothe muscles of facial expression*

A. Temporal branch (with zygomaticbranch) innervates orbicularis oculi--closes eyelids

B. Zygomatic branch (with buccal branch)innervates zygomaticus major--smiling

C. Buccal branch innervatesbuccinator--tenses cheek

D. Mandibular branch innervatesdepressor angularis oris--frowning

E. Cervical branch innervates platysma --lowers mandible, tenses skin of anteriorneck

*These are key innervations to the musclesof facial expression. However, each nervebranch innervates multiple muscles andeach muscle receives multiple nervebranches.

SVE


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A. The temporal and zygomatic branches of the facialnerve provide SVE nerve fibers that innervate the ipsilateralorbicularis oculi, the muscle responsible for closing theeyelid.


Temporal branch

Zygomatic branch

SVEContraction of orbicularisoculi causes the eyelid to close


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B. The zygomatic and buccal branches of the facial nerveinnervate the ipsilateral zygomaticus major muscle, themain muscle responsible for smiling.


Zygomatic branch

SVE

Zygomaticusmajor muscle

Contraction of the zygomaticus major musclecauses smiling


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C. The buccal branch of the facial nerve innervates thebuccinator muscle, the muscle responsible for holding thecheek against the teeth, thus positioning food for chewing.


Buccal branch offacial nerve innervatesBuccinator muscle.

SVE Contraction of the buccinator musclecauses tensing of the cheek whichhelps position food within the occusal planefor chewing


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D. The mandibular and buccal branches of the facial nerveinnervate the ipsilateral depressor angularis oris muscle, amuscle responsible for frowning.


Mandibularbranch

SVE

Depressorangularis oris

Contraction of thedepressor angularis orismuscle causes frowning


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E. The cervical branch of the facial nerve innervates theplatysma muscle, a muscle partly responsible for depressing themandible.


Platysma muscle

Cervical branch offacial nerve innervatesPlatysma muscle.

Contraction of platysmaMuscle results in depressionof mandible.

SVE


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E. The cervical branch of the facial nerve innervates theplatysma muscle (the shaving muscle ), a muscleresponsible for tightening the skin of the anterior neck.


Platysma muscle

Cervical branch offacial nerve innervatesPlatysma muscle.

Contraction of platysmamuscle causes the skin of theanterior neck to tighten.

SVE


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Stapedius muscledampensmovement ofossicles.

Summary ofSVE

Facialcanal


StylomastoidForamen


Temporal-orbicularis oculicloses eyelids.

Zygomatic-zygomaticus majorpartly responsible for smiling.Buccal-buccinator tenses cheekMandibular-depressor angularisoris responsible for frowning.Cervical- platysma helps lowermandible and tightens skin ofneck.

Posterior auricularmuscle responsible forposterior displacementof pinna.

Facial nerve

Facial nerve

Posterior bellyof digastricelevates hyoidbone.

Stylohyoid muscleelevates hyoid bone.


Facialnucleus


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GVA Component of the

Facial NerveThe next slide demonstrates that GVA is

responsible for providing:1. Light touch, temperature, and pain

sensation from the soft palate via the

greater superficial petrosal nerve(GSPN).

Click here to start GVA


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1. GVA provides sensation of light touch,temperature, and pain from the soft palate.

softpalate

Light touch, temperature,and pain fromthe soft palate

Click here for animation

GVA

Light touch sensation

Temperature sensation

Pain sensation

GSPN

Facial nerve


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Through thehiatus of canal ofGSPN

Light touch,temperature,and pain fromthe soft palate

Through theinternal acousticmeatus

Summaryof GVA

Through thePterygoid canal


Pterygoidcanal

Facial

canal

Through thelesser palatinecanalGSPN

Facial nerve


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SVA Component of the

Facial NerveThe next two slides demonstrate that SVA

is responsible for providing:

1. Taste from the hard and soft palate viathe greater superficial petrosal nerve(GSPN).

2. Taste from the anterior 2/3 of thetongue via the chorda tympani nerve.



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1. SVA provides taste sensation from the hard andsoft palate via the GSPN.

Softpalate

Taste from the hardand soft palate


Hard palate

CoSweetenedcoffee

SVA

GSPN branches fromthe facial nerve at thegeniculate ganglionwithin the genu of thefacial canal. It is made upof fibers from SVA ,GVE , and GVA .


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2. SVA provides taste to the anterior 2/3 ofthe tongue via the chorda tympani nerve.


Taste from the anterior2/3 of the tongue

SVA

Chordatympani

Hi f l f


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Taste from hardand soft palate.

Summaryof SVA

Lacerate foramen

Click here to start animation

Facialcanal


StylomastoidForamen


Taste fromanterior 2/3tongue.

Pterygoidcanal

Chorda tympani

GSPN




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GVE Component of theFacial Nerve

1. Via the pterygopalatine ganglion GVE provides: A. Lacrimation (tearing of the eye)B. Mucus secretions of the nasal cavityC. Mucus secretions of the oral cavity

2. Via innervation of the submandibular ganglion

GVE provides: A. Salivation of the oral cavity

Click to start Animation of GVE component


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1. The GVE component of the facial nerve transmits preganglionicfibers to the pterygopalatine ganglion via the GSPN. From thepterygopalatine ganglion postganglionic fibers cause ipsilaterallacrimation and mucus secretions of the nasal and oral cavities.

Pterygopalatineganglion

Lacrimal nucleus


A. Tearing of eye

B. Mucus secretion ofnasal cavities

C. Mucus secretionof hard and softpalate.

GVELacrimal gland

GSPN


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2. The GVE component of the facial nerve transmits preganglionicfibers to the submandibular ganglion via the chorda tympani nerve.From the submandibular ganglion postganglionic fibers innervate thesubmandibular and sublingual glands, causing salivation.

Superior salivarynucleus


Submandibularganglion

Submandibulargland

Sublingulalgland

GVE

Chordatympani


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GSA Component of the

Facial NerveGSA is responsible for providing:

1. Touch, temperature, and pain sensation frompart of the external acoustic meatus via theposterior auricular nerve.

Click here to start GSA


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1. GSA provides touch, temperature, and painsensation from the external acoustic meatus.


Cotton swab

Touch, temperature,and pain sensationfrom part of theexternal acousticmeatus.

GSA

Posteriorauricularnerve

fForamen Rotundem Inferior Orbital Fissure


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Touch, temperature,and pain sensationfrom the externalacoustic meatus.

Summary ofGSA


StylomastoidForamen


Facialcanal

Facial nerve

Facial nerve

Posteriorauricularnerve


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Summary of functional components

Each of the five functional components of thefacial nerve SVE , GVA , SVA , GVE , and GSA have a unique function. Knowledge of these

functional components can be applied to clinicalobservations to aid in localizing lesions of nervebranches or at anatomical landmarks.

The following slides provide examples of howlesions at different locations can effect function.


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Question #1

A. Paralysis of facial muscles

B. Decreased sensation soft palate

C. Decreased hearing sensivity

D. Loss of taste to the soft palate

A. Paralysis of facial muscles

B. Decreased sensation of soft palate

C. Increased sensitivity to loud noise

D. Loss of taste of hard palate

One effect of a lesion here, betweenthe branching of the stapedial nerveand the branching of the chordatympani nerve, would be:


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Q i #3


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Question #3

One effect of a lesion here, at thestylomastoid foramen will be:

A. Loss of light touch from the soft palate

B. Loss of salivation of oral cavity

C. Increased sensitivity to loud noises

D.Partial loss of sensation of external acoustic meatus


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Question #4

A lesion here, between the branchingof the GSPN and the branching of thestapedial nerve, will spare:

A. Taste of anterior 2/3 of tongue

B. Taste of hard palate

C. Salivation in oral cavity

D. Ipsilateral facial expression


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Question #5

A lesion here, between thebranching of the GSPN and thebranching of the stapedial nerve,will also spare:

A. Light touch from the soft palate

B. Ability to smile

C. Taste from the anterior 2/3 of tongue

D. Protection of the inner ear from loud noises


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Thank You

Return to SVE Return to GVA Return to SVA

Return to GVE Return to GSA

Return to Lesion Questions


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IncorrectThe GVA component of the GSPN, which is spared by this lesion,is responsible for providing sensation from the soft palate.

Please try again


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IncorrectThe stapedial nerve ( SVE ), which is spared by this lesion, is

responsible for protecting the ear from increased sensitivity to loudnoises.

Please try again


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IncorrectThe SVA component of the GSPN, which is spared by this lesion,

is responsible for providing taste from the hard palate.

Please try again


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IncorrectThe GVA component of the GSPN, which is spared by this lesion,is responsible for providing light touch from the soft palate.

Please try again


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IncorrectThe SVA component of the GSPN, which is spared by this lesion,

is responsible for providing taste from the soft palate.

Please try again


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IncorrectThe GVA component of the GSPN, which is spared by this lesion,

is responsible for providing temperature sensation fromthe soft palate.

Please try again


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IncorrectThe GVA component of the GSPN, which is spared by this lesion,is responsible for providing light touch from the soft palate.

Please try again


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IncorrectThe GVE component of the chorda tympani nerve, which is spared

by this lesion, is responsible for providing salivationof the oral cavity.

Please try again


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IncorrectThe stapedial nerve ( SVE ), which is spared by this lesion, is

responsible for protecting the ear from increased sensitivity to loudnoises.

Please try again


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IncorrectThis lesion will not spare taste to the anterior 2/3 of the tongue,

which is supplied via the SVA component of the chorda tympaninerve.

Please try again


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IncorrectThis lesion will not spare salivation of the oral cavity, which issupplied by the GVE component of the chorda tympani nerve.

Please try again


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IncorrectThis lesion will not spare ipsilateral facial expression, which is

supplied by the temporal, zygomatic, buccal, mandibular, andcervical branches of the facial nerve ( SVE ).

Please try again


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IncorrectThis lesion will not spare the ability to smile, which is supplied by

the zygomatic branch of the facial nerve ( SVE ).

Please try again


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IncorrectThis lesion will not spare the ability to taste from the anterior 2/3 of

the tongue, which is supplied by the SVA component of the chordatympani nerve.

Please try again


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IncorrectThis lesion will not spare the ability to smile, which is supplied by

the zygomatic branch of the facial nerve ( SVE ).

Please try again


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IncorrectThis lesion will not spare the ability to protect the ear from loud

noises, which is supplied by the stapedial nerve ( SVE ).

Please try again

Correct!


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Correct! A lesion here will cause paralysis of facial muscles due

to its disruption of the SVE component.

Next questionGo back to question 1


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Correct! A lesion here will cause a loss of taste to the anterior 2/3 of the

tongue due to the disruption of the SVA component ofthe chorda tympani nerve.


Correct!


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Correct! A lesion here will cause partial loss of sensation (light touch,temperature, and pain) of the external acoustic meatus due to

disruption of the GSA component of the posterior auricular nerve.


Correct!


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Correct! A lesion here will spare a persons ability to taste on the hard and softpalate because the SVA component of the Greater Superficial Petrosal

Nerve (GSPN) remains intact.


C !


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Correct! A lesion here will spare the sensation of light touch of the soft palate

because the GVA component of the GSPN remains intact.

G b k t ti 5 C ti

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Facialis Ideg Nagyon Jo