Nerve Of face

NERVE SUPPLY OF FACE

Motor Nerve Supply Motor Clinical Anatomy Sensory Nerve Supply Cutaneous Nerves Sensory Distribution Sensory Clinical Anatomy

1 Motor Nerve Supply

  • Facial nerve is the motor nerve of the face.
  • Its five terminal branches emerge from the parotid gland and diverge to supply the various facial muscles:
  1. Temporal
  2. Zygomatic
  3. Buccal
  4. Marginal mandibular
  5. Cervical

Terminal Branches of Facial Nerve

1. Temporal Branch

  • Crosses the zygomatic arch.
  • Gives branches to:
    • Frontalis
    • Auricular muscles
    • Orbicularis oculi

2. Zygomatic Branch

  • Crosses the zygomatic bone.
  • Gives branches to:
    • Orbicularis oculi (lower eyelid part).

3. Buccal Branch

  • Supplies muscles of:
    • Cheek
    • Upper lip

4. Marginal Mandibular Branch

  • Supplies muscles of the lower lip.

5. Cervical Branch

  • Innervates platysma.

2 Clinical Anatomy

Clinical Testing of Muscles of Facial Expression

The facial nerve is examined by testing the following facial muscles:

a. Frontalis

  • Ask the patient to look upwards without moving the head.
  • Look for normal horizontal wrinkles on the forehead.

b. Dilators of Mouth

  • Ask the patient to show the teeth.

c. Orbicularis Oculi

  • Test by tight closure of the eyes.

d. Buccinator

  • Ask the patient to puff the mouth.
  • Then blow forcibly as in whistling.

Facial Nerve Palsy

Bell’s Palsy

  • Infranuclear lesion of the facial nerve at the stylomastoid foramen is known as Bell’s palsy.
  • Upper and lower quarters of the muscles of face on the same side are paralysed.
  • There is atrophy of facial muscles.
  • It also causes loss of taste in most of the anterior 2/3rd of the tongue.
  • Face becomes asymmetrical and is drawn up to the normal side.
  • Affected side is motionless.
  • Wrinkles disappear from the forehead.
  • Eye cannot be closed → leading to keratitis.
  • Any attempt to smile draws the mouth to the normal side.
  • During mastication, food accumulates between the teeth and cheek.
  • Articulation of labials is impaired.
  • Tears flow out from the eye.
  • Saliva flows down from the angle of mouth.

Supranuclear Facial Nerve Palsy

  • In supranuclear lesions of the facial nerve, usually a part of hemiplegia with injury of corticonuclear fibres:
  • Only the lower quarter of the opposite side of face is paralysed.
  • Upper quarter containing:
    • Frontalis
    • Orbicularis oculi
    escapes due to its bilateral representation in the cerebral cortex.
  • Only voluntary movements are affected.
  • Emotional expressions remain normal because there are separate pathways for:
    • Voluntary movements.
    • Emotional movements.
  • There is no atrophy of facial muscles.

3 Sensory Nerve Supply of Face

  • Trigeminal nerve, through its three branches, is the chief sensory nerve of the face.
  • Skin over the jaw and over the parotid gland is supplied by the great auricular nerve (C2, C3).

4 Cutaneous Nerves of Face

A. Ophthalmic Division of Trigeminal Nerve

1. Supratrochlear nerve
Area → Upper eyelid and forehead
2. Supraorbital nerve
Area → Upper eyelid, frontal air sinus, scalp
3. Lacrimal nerve
Area → Lateral part of upper eyelid
4. Infratrochlear nerve
Area → Medial parts of both eyelids
5. External nasal nerve
Area → Lower part of dorsum and tip of nose

B. Maxillary Division of Trigeminal Nerve

6. Infraorbital nerve
Area → Lower eyelid, side of nose and upper lip
7. Zygomaticofacial nerve
Area → Upper part of cheek
8. Zygomaticotemporal nerve
Area → Anterior part of temporal region

C. Mandibular Division of Trigeminal Nerve

9. Auriculotemporal nerve
Area → Upper two-thirds of lateral side of auricle and temporal region
10. Buccal nerve
Area → Skin of lower part of cheek
11. Mental nerve
Area → Skin over chin

D. Cervical Plexus

12. Anterior division of great auricular nerve (C2, C3)
Area → Skin over angle of jaw and over parotid gland
13. Upper and lower divisions of transverse cutaneous nerve of neck (C2, C3)
Area → Lower margin of lower jaw and upper part of neck
14. Lesser occipital nerve
Area → Back of auricle
15. Supraclavicular nerve
Area:
  • Front of thorax till 2nd costal cartilage.
  • Skin over upper ½ of deltoid muscle.

5 Sensory Distribution of Trigeminal Nerve

In addition to most of the skin of the face, the sensory distribution of the trigeminal nerve is also to:

  • Nasal cavity
  • Paranasal air sinuses
  • Eyeball
  • Mouth cavity
  • Palate
  • Cheeks
  • Gums
  • Teeth
  • Anterior 2/3rd of tongue
  • Supratentorial part of dura mater
  • Including the dura lining the:
    • Anterior cranial fossa
    • Middle cranial fossa

6 Clinical Anatomy

Headache and Sensory Distribution of Trigeminal Nerve

  • Sensory distribution of the trigeminal nerve explains why headache is a uniformly common symptom in involvement of:
  • Nose:
    • Common cold
    • Boils
  • Paranasal air sinuses:
    • Sinusitis
  • Infections and inflammations of:
    • Teeth
    • Gums
  • Refractive errors of the eyes.
  • Infection of the meninges, as in meningitis.

Trigeminal Neuralgia (Tic Douloureux)

  • May involve one or more of the three divisions of the trigeminal nerve.
  • Causes attacks of very severe:
    • Burning pain.
    • Scalding pain.
  • Pain occurs along the distribution of the affected nerve.
  • Pain is relieved either:
    • By injecting 90% alcohol into the affected division of the trigeminal ganglion.
    • By sectioning the affected nerve, the main sensory root, or the spinal tract of the trigeminal nerve, which is situated superficially in the medulla.
  • The procedure is called medullary tractotomy.