1. The Facial Nerve: Functional Components and Anatomy

2. 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.

3. 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

4. The remainder of this tutorial focuses on the functional nerve components contained within the facial nerve:
SVE
GVA
SVA
GVE
GSA
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.

5. 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)

6. 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.

7. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa (PCF)
Facial
canal
Petrotympanic
fissure
Facial nerve
Stylomastoid
Foramen
Chorda tympani nerve
Facial nerve
Posterior
auricular N.
The facial nerve exits the posterior cranial fossa (PCF) at the internal acoustic meatus.
Click here to start Animation

8. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa
Facial
canal
Petrotympanic
fissure
Facial nerve
Stylomastoid
Foramen
Chorda tympani
Facial nerve
Posterior
auricular N.
Within the internal acoustic meatus the facial nerve enters the facial canal.
Click here to start Animation

9. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Geniculate ganglion
MCF
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa
Facial
canal
Petrotympanic
fissure
Facial nerve
Stylomastoid
Foramen
Chorda tympani
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.
Click here to start Animation

10. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa
Facial
canal
Petrotympanic
fissure
Stapedial N.
Facial nerve
Stylomastoid
Foramen
Chorda tympani
Facial nerve
Posterior
auricular N.
The second branch of the facial nerve, the stapedial nerve, branches from the descending portion of the facial nerve and enters the middle ear.
Click here to start Animation

11. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa
Facial
canal
Petrotympanic
fissure
Facial nerve
Chorda tympani N.
Stylomastoid
Foramen
Infratemporal
fossa
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.
Click here to start Animation

12. Overview of Facial Nerve anatomy in the skull
Inferior Orbital Fissure
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
Greater superficial
Petrosal nerve (GSPN)
Posterior
Cranial
Fossa
Facial
canal
Petrotympanic
fissure
Facial nerve
Stylomastoid
Foramen
Chorda tympani
Facial nerve
Parotid
region
Posterior
auricular N.
The descending portion of the facial nerve exits the facial canal at the stylomastoid foramen and continues into the parotid region
Click here to start Animation

13. Functional components of the Facial Nerve (CN VII)1.
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. 2. 3. 4. 5.
Click on numbers for functional components

14. SVE Component of the Facial Nerve
The next 11 slides demonstrate innervation to muscles derived from the 2nd branchial arch:
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 bone
4. Posterior belly of digastric -- elevates hyoid bone, depresses mandible
5. Muscles of facial expression -- blinking, smiling, frowning, facial movements
Click here to start Animation of SVE component

15. \ SVE 1. The Stapedius muscle dampens movement of the ossicles
Stapedius muscle dampens movement of the ossicles protecting the inner ear from damage from loud noises
Click here to start Animation

16. 2. The Posterior Auricular nerve innervates the posterior auricular muscle, pulling the pinna posteriorly.
SVE
Posterior auricular
muscle pulls the pinna posteriorly
SVE component of posterior auricular nerve
Click here to start Animation

17. 3. The Stylohyoid muscle elevates the hyoid bone
SVE
Through the internal
Acoustic meatus
Stylohyoid muscle elevates the hyoid bone.
Through the stylomastoid
foramen
Stylohyoid branch of facial nerve
innervates stylohyoid muscle
Click here to start Animation

18. SVE 4. The Posterior belly of digastric muscle elevates the hyoid bone
Through the internal
acoustic meatus
Posterior belly of digastric muscle elevates the hyoid bone
Through the stylomastoid
foramen
Posterior belly of digastric branch of facial nerve
innervates posterior belly of digastric muscle.
Click here to start Animation

19. 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
Buccal branch innervates
buccinator--tenses cheek
Mandibular branch innervates depressor angularis oris--frowning
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

20. 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.
Contraction of orbicularis
oculi causes the eyelid to close
SVE
Temporal branch
Zygomatic branch
Click here to start Animation

21. B. The zygomatic and buccal branches of the facial nerve innervate the ipsilateral zygomaticus major muscle, the main muscle responsible for smiling.
SVE
Zygomaticus
major muscle
Contraction of the zygomaticus major muscle
causes smiling
Zygomatic branch
Click here to start Animation

22. 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.
SVE
Contraction of the buccinator muscle
causes tensing of the cheek which
helps position food within the occusal plane
for chewing
Buccal branch of
facial nerve innervates
Buccinator muscle.
Click here to start Animation

23. D. The mandibular and buccal branches of the facial nerve innervate the ipsilateral depressor angularis oris muscle, a muscle responsible for frowning.
SVE
Contraction of the
depressor angularis oris
muscle causes frowning
Mandibular branch
Depressor
angularis oris
Click here to start Animation

24. E. The cervical branch of the facial nerve innervates the platysma muscle, a muscle partly responsible for depressing the mandible.
SVE
Contraction of platysma
Muscle results in depression
of mandible.
Platysma muscle
Cervical branch of
facial nerve innervates
Platysma muscle.
Click here to start Animation

25. 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.
SVE
Contraction of platysma
muscle causes the skin of the anterior neck to tighten.
Platysma muscle
Cervical branch of
facial nerve innervates
Platysma muscle.
Click here to start Animation

26. Summary of SVE Click here to start Animation Facial canal
Internal Acoustic
Meatus
Facial
nucleus
Stapedius muscle dampens movement of ossicles.
Facial
canal
Facial nerve
Stylomastoid
Foramen
Facial nerve
Posterior
auricular N.
Temporal-orbicularis oculi
closes eyelids.
Zygomatic-zygomaticus major
partly responsible for smiling.
Buccal-buccinator tenses cheek
Mandibular-depressor angularis oris responsible for frowning.
Cervical- platysma helps lower mandible and tightens skin of neck.
Posterior auricular
muscle responsible for
posterior displacement
of pinna.
Posterior belly of digastric
elevates hyoid bone.
Stylohyoid muscle
elevates hyoid bone.
Click here to start Animation
*Right click on image and save to local file for full page printing from Word, Illustrator, etc. Top of page The Structural Basis of Medical Practice - Human Gross Anatomy, Radiology, Embryology The Pennsylvania State University © College of Medicine

27. GVA Component of the Facial Nerve
The next slide demonstrates that GVA is responsible for providing:
Light touch, temperature, and pain sensation from the soft palate via the greater superficial petrosal nerve (GSPN).
Click here to start GVA

28. Click here for animation
1. GVA provides sensation of light touch, temperature, and pain from the soft palate.
GVA
Temperature sensation
soft palate
GSPN
Light touch sensation
Pain sensation
Facial nerve
Light touch, temperature,
and pain from
the soft palate
Click here for animation

29. Click here for animation
Summary of GVA
Through the
Pterygoid canal
Through the hiatus of canal of GSPN
Through the
lesser palatine
canal
Pterygoid canal
Through the internal acoustic meatus
GSPN
Facial
canal
Facial nerve
Light touch, temperature, and pain from the soft palate
Click here for animation

30. SVA Component of the Facial Nerve
The next two slides demonstrate that SVA is responsible for providing:
Taste from the hard and soft palate via the greater superficial petrosal nerve (GSPN).
Taste from the anterior 2/3 of the tongue via the chorda tympani nerve.
Click here for animation

31. 1. SVA provides taste sensation from the hard and soft palate via the GSPN.
Hard palate
Soft palate
GSPN branches from
the facial nerve at the
geniculate ganglion
within the genu of the
facial canal. It is made up
of fibers from SVA,
GVE, and GVA. Co
Sweetened coffee
Taste from the hard and soft palate
Click here for animation

32. 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
Click here for animation

33. Click here to start animation
Summary of SVA
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
Internal Acoustic
Meatus
Pterygoid canal
Greater and
lesser palatine
canals
GSPN
Facial
canal
Petrotympanic
fissure
Chorda tympani
Stylomastoid
Foramen
Taste from hard and soft palate.
Taste from anterior 2/3 tongue.
Click here to start animation

34. GVE Component of the Facial 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

35. Click here to start Animation
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.
GVE
GSPN
Lacrimal gland
Pterygopalatine
ganglion
A. Tearing of eye
Lacrimal nucleus
B. Mucus secretion of nasal cavities
C. Mucus secretion of hard and soft palate.
Click here to start Animation

36. Click here to start Animation
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.
GVE
Sublingulal
gland
Submandibular
gland
Superior salivary
nucleus
Chorda
tympani
Submandibular
ganglion
Click here to start Animation

37. Click here to start animation
Inferior Orbital Fissure
Summary of GVE
Hiatus of canal of greater superficial petrosal nerve
Lacerate foramen
GSPN
From the pterygopalatine ganglion
postganglionic GVE fibers
provide lacrimation of the
eyes and mucus secretion of the
nasal cavity and oral cavity.
Greater and
lesser palatine
canals
Pterygoid canal
Internal Acoustic
Meatus
Facial
canal
Petrotympanic fissure
Superior salivary
and lacrimal nucleus
Chorda tympani
From the submandibular
ganglion postganglionic
GVE fibers provide
salivation in the oral cavity.
Click here to start animation

38. GSA Component of the Facial 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

39. Click here to start animation
1. GSA provides touch, temperature, and pain sensation from the external acoustic meatus.
Cotton swab
GSA
Touch, temperature, and pain sensation from part of the external acoustic meatus.
Posterior
auricular
nerve
Click here to start animation

40. Click here to start animation
Foramen Rotundem
Inferior Orbital Fissure
Summary of GSA
Internal Acoustic
Meatus
Facial
canal
Facial nerve
Stylomastoid
Foramen
Facial nerve
Touch, temperature, and pain sensation from the external acoustic meatus.
Posterior
auricular
nerve
Click here to start animation

41. 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.

42. Question #1
One effect of a lesion here, between the branching of the stapedial nerve and the branching of the chorda tympani nerve, would be:
A. Paralysis of facial muscles
A. Paralysis of facial muscles
B. Decreased sensation of soft palate
B. Decreased sensation soft palate
C. Increased sensitivity to loud noise
C. Decreased hearing sensivity
D. Loss of taste of hard palate
D. Loss of taste to the soft palate

43. 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.

44. 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

45. 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

46. 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

47. Return to Lesion Questions
Thank You
Return to SVE
Return to GVA
Return to SVA
Return to GVE
Return to GSA
Return to Lesion Questions

48. Incorrect The GVA component of the GSPN, which is spared by this lesion, is responsible for providing sensation from the soft palate.
Please try again

49. 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

50. 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

51. Incorrect The GVA component of the GSPN, which is spared by this lesion, is responsible for providing light touch from the soft palate.
Please try again

52. 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

53. Incorrect The GVA component of the GSPN, which is spared by this lesion, is responsible for providing temperature sensation from the soft palate.
Please try again

54. Incorrect The GVA component of the GSPN, which is spared by this lesion, is responsible for providing light touch from the soft palate.
Please try again

55. Incorrect The 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

56. 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

57. Incorrect This 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

58. Incorrect This lesion will not spare salivation of the oral cavity, which is supplied by the GVE component of the chorda tympani nerve.
Please try again

59. Incorrect This 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

60. Incorrect This lesion will not spare the ability to smile, which is supplied by the zygomatic branch of the facial nerve (SVE).
Please try again

61. Incorrect This 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

62. Incorrect This lesion will not spare the ability to smile, which is supplied by the zygomatic branch of the facial nerve (SVE).
Please try again

63. Incorrect This lesion will not spare the ability to protect the ear from loud noises, which is supplied by the stapedial nerve (SVE).
Please try again

64. Correct! A lesion here will cause paralysis of facial muscles due to its disruption of the SVE component.
Go back to question 1
Next question

65. 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.
Go back to question 2
Next question

66. 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.
Go back to question 3
Next question

67. 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.
Go back to question 4
Next question

68. 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
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