facial nerve animation 01

The Facial Nerve: Functional Components and

Anatomy

Brief overview of cranial nerve functional components

• The 12 cranial nerves participate in a total of seven neural functions. Each of these 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 damage to each provides the basis of the thorough neurological exam.

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 – Doesn’t exist

• SVA – Special Visceral Afferent

– Taste and olfaction

• SVE – Special Visceral Efferent– Motor to muscles derived from the branchial arches

The remainder of this tutorial focuses on the functional nerve components contained within the facial nerve:

SVEGVASVAGVEGSA

These components, either alone or in combination, make up the facial nerve and its branches. An understanding of these components can serve as a template for understanding the other functional components. In addition, an understanding of the facial nerve and its components can be applied in clinical situations to help localize a patient’s defect.

Functional Components Within Branches of the Facial 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

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 the facial canal and enters the middle cranial fossa by way of the hiatus of the canal for the GSPN.

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

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

• The descending portion of the facial nerve continues into the parotid region by way of the stylomastoid foramen.

Overview of Facial Nerve anatomy in the skull

Lacerate foramen

Facial canal

Internal AcousticMeatus

StylomastoidForamen

Hiatus of canal of greater superficial petrosal nerve

Pterygoid canal

Greater superficialPetrosal nerve (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 acoustic meatus.

Click here to start Animation

Posteriorauricular N.


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal




Chorda tympani

Facial nerve

Facial nerve

PosteriorCranialFossa



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



Lacerate foramen


StylomastoidForamen


Pterygoid canal




Chorda tympani

Facial nerve

Facial nerve




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

Geniculate ganglion

Facial canal

MCF


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal



Chorda tympani

Facial nerve

Facial nerve




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

Stapedial N. Petrotympanicfissure



Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal




Chorda tympani N.

Facial nerve

Facial nerve




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

Infratemporalfossa


Lacerate foramen

Facial canal


StylomastoidForamen


Pterygoid canal




Chorda tympani

Facial nerve

Facial nerve




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

ParotidregionPosterior

auricular N.

Functional components of the Facial Nerve (CN VII)

• SVE (Special Visceral Efferent) — Motor to striated muscles derived from the 2nd branchial arch.

• GVA (General Visceral Afferent) — Sensory from 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

SVE Component of theFacial Nerve

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

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

2. Posterior auricular muscle -- posterior movement of 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

\Stapedius muscle dampens movement of the ossicles protecting the inner ear from damage from loud noises

SVE


1. The Stapedius muscle dampens movement of the ossicles

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


SVE component of posterior auricular nerve

Posterior auricularmuscle pulls the pinna posteriorly

SVE

Stylohyoid muscle elevates the hyoid bone.

Through the internalAcoustic meatus

Through the stylomastoidforamen

3. The Stylohyoid muscle elevates the hyoid bone


Stylohyoid branch of facial nerveinnervates stylohyoid muscle

SVE

Through the stylomastoidforamen

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


Posterior belly of digastric branch of facial nerveinnervates posterior belly of digastric muscle.

Posterior belly of digastric muscle elevates the hyoid bone

SVEThrough the internalacoustic meatus

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

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

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

C. Buccal branch innervatesbuccinator--tenses cheek

D. Mandibular branch innervates depressor angularis oris--frowning

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

*These are key innervations to the muscles of facial expression. However, each nerve branch innervates multiple muscles and each muscle receives multiple nerve branches.

SVE

A. The temporal and zygomatic branches of the facial nerve provide SVE nerve fibers that innervate the ipsilateral orbicularis oculi, the muscle responsible for closing the eyelid.


Temporal branch

Zygomatic branch

SVEContraction of orbicularisoculi causes the eyelid to close

B. The zygomatic and buccal branches of the facial nerve innervate the ipsilateral zygomaticus major muscle, the main muscle responsible for smiling.


Zygomatic branch

SVE

Zygomaticus major muscle

Contraction of the zygomaticus major musclecauses smiling

C. The buccal branch of the facial nerve innervates the buccinator muscle, the muscle responsible for holding the cheek 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

D. The mandibular and buccal branches of the facial nerve innervate the ipsilateral depressor angularis oris muscle, a muscle responsible for frowning.


Mandibular branch

SVE

Depressorangularis oris

Contraction of thedepressor angularis orismuscle causes frowning

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


Platysma muscle

Cervical branch offacial nerve innervates

Platysma muscle.

Contraction of platysmaMuscle results in depressionof mandible.

SVE

E. The cervical branch of the facial nerve innervates the platysma muscle (the “shaving muscle”), a muscle responsible for tightening the skin of the anterior neck.


Platysma muscle

Cervical branch offacial nerve innervates

Platysma muscle.

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

SVE

Stapedius muscle dampens movement of ossicles.

Summary of SVE

Facial canal


StylomastoidForamen


Temporal-orbicularis oculi closes eyelids.Zygomatic-zygomaticus majorpartly responsible for smiling.Buccal-buccinator tenses cheekMandibular-depressor angularis oris responsible for frowning.Cervical- platysma helps lower mandible and tightens skin of neck.

Posterior auricularmuscle responsible forposterior displacementof pinna.

Facial nerve

Facial nerve

Posterior belly of digastricelevates hyoid bone.

Stylohyoid muscleelevates hyoid bone.


Facialnucleus

GVA Component of the Facial Nerve

The 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

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

soft palate

Light touch, temperature,and pain fromthe soft palate

Click here for animation

GVA

Light touch sensation

Temperature sensation

Pain sensation

GSPN

Facial nerve

Through the hiatus of canal of GSPN

Light touch, temperature, and pain from the soft palate

Through the internal acoustic meatus

Summary of GVA

Through the Pterygoid canal


Pterygoid canal

Facial canal

Through the lesser palatinecanalGSPN

Facial nerve

SVA Component of the Facial Nerve

The next two slides demonstrate that SVA is responsible for providing:

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

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


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

Soft palate

Taste from the hard and soft palate


Hard palate

CoSweetened coffee

SVA

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

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


Taste from the anterior 2/3 of the tongue

SVA

Chorda tympani

Taste from hard and soft palate.

Summary of SVA

Lacerate foramen

Click here to start animation

Facial canal


StylomastoidForamen


Taste from anterior 2/3 tongue.

Pterygoid canal

Chorda tympani

GSPN



GVE Component of theFacial Nerve

1. Via the pterygopalatine ganglion GVE provides:

A. Lacrimation (tearing of the eye)

B. Mucus secretions of the nasal cavity

C. 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

1. The GVE component of the facial nerve transmits preganglionic fibers to the pterygopalatine ganglion via the GSPN. From the pterygopalatine ganglion postganglionic fibers cause ipsilateral

lacrimation and mucus secretions of the nasal and oral cavities.

Pterygopalatineganglion

Lacrimal nucleus


A. Tearing of eye

B. Mucus secretion of nasal cavities

C. Mucus secretion of hard and soft palate.

GVELacrimal gland

GSPN

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

Superior salivary nucleus


Submandibularganglion

Submandibulargland

Sublingulalgland

GVE

Chordatympani

Summary of GVE

Lacerate foramen


Facial canal


Superior salivary and lacrimal nucleus

Pterygoid canal

From the pterygopalatine ganglionpostganglionic GVE fibersprovide lacrimation of theeyes and mucus secretion of thenasal cavity and oral cavity.

From the submandibularganglion postganglionicGVE fibers providesalivation in the oral cavity.

Petrotympanic fissure

Chorda tympani

GSPN




GSA Component of theFacial Nerve

GSA is responsible for providing:

1. Touch, temperature, and pain sensation from part of the external acoustic meatus via the posterior auricular nerve.

Click here to start GSA

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


Cotton swab

Touch, temperature, and pain sensation from part of the external acoustic meatus.

GSA

Posteriorauricularnerve

Touch, temperature, and pain sensation from the external acoustic meatus.

Summary of GSA


StylomastoidForamen

Foramen Rotundem Inferior Orbital Fissure


Facial canal

Facial nerve

Facial nerve

Posteriorauricularnerve

Summary of functional components

• Each of the five functional components of the facial nerve SVE, GVA, SVA, GVE, and GSA have a unique function. Knowledge of these functional components can be applied to clinical observations to aid in localizing lesions of nerve branches or at anatomical landmarks.

• The following slides provide examples of how lesions at different locations can effect function.

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, between the branching of the stapedial nerve and the branching of the chorda tympani nerve, would be:

Question #2

A lesion here, between the branching of the stapedial nerve and the branching of the chorda tympani nerve, will also cause?

A. Loss of light touch from the soft palate

B. Loss of taste from the soft palate

C. Loss of taste of anterior 2/3 of tongue

D. Loss of temperature from the soft palate.

Question #3

One effect of a lesion here, at the stylomastoid 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

Question #4

A lesion here, between the branching of the GSPN and the branching of the stapedial 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

Question #5

A lesion here, between the branching of the GSPN and the branching 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

Thank You

Return to SVE Return to GVA Return to SVA

Return to GVE Return to GSA

Return to Lesion Questions

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

is responsible for providing sensation from the soft palate.

Please try again

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

responsible for protecting the ear from increased sensitivity to loud noises.

Please try again

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

is responsible for providing taste from the hard palate.

Please try again


is responsible for providing light touch from the soft palate.

Please try again

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

is responsible for providing taste from the soft palate.

Please try again


is responsible for providing temperature sensation from the soft palate.

Please try again


is responsible for providing light touch from the soft palate.

Please try again

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

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

Please try again

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

responsible for protecting the ear from increased sensitivity to loud noises.

Please try again

IncorrectThis lesion will not spare taste to the anterior 2/3 of the tongue, which is supplied via the SVA component of the chorda tympani

nerve.

Please try again

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

Please try again

IncorrectThis lesion will not spare ipsilateral facial expression, which is supplied by the temporal, zygomatic, buccal, mandibular, and

cervical branches of the facial nerve (SVE).

Please try again

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

the zygomatic branch of the facial nerve (SVE).

Please try again

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 chorda

tympani nerve.

Please try again

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

the zygomatic branch of the facial nerve (SVE).

Please try again

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!A lesion here will cause paralysis of facial muscles due

to its disruption of the SVE component.

Next questionGo back to question 1

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 of the chorda tympani nerve.


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!A lesion here will spare a person’s ability to taste on the hard and soft

palate because the SVA component of the Greater Superficial Petrosal Nerve (GSPN) remains intact.


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

because the GVA component of the GSPN remains intact.

Go back to question 5 Continue

facial nerve animation 01

Documents

internal acoustic meatus

skullinternal acoustic meatus

lesser palatine canals

external acoustic meatus

2nd branchial arch

posterior cranial fossa

posterior auricular nerve

chorda tympani nerve