QS Study

Effects of Lesion of Facial Nerve

The facial nerve is the seventh cranial nerve which conies both motor and sensory fibers. It is composed of approximately 10,000 neurons, 7,000 of which are myelinated and innervate the nerves of facial expression. It is the seventh paired cranial nerve.

The facial nerve may be injured or may become dysfunctioned anywhere from the brainstem to the face.

The major presentations of facial nerve lesions are –

  1. Loss of motor function of the facial muscles (e.g. pt. can’t blow).
  2. Deviation of the angle of the mouth to the same side.
  3. An absence of wrinkles over the forehead.
  4. Unable to close eye properly.
  5. Dropping of fluid through the angle of mouth during drinking.
  6. Retention of food particles in the angle of the mouth.
  7. Unable to show the teeth of the upper jaw.
  8. Excessive sensitivity to sound in one ear.
  9. Loss of taste over the anterior two-thirds of the tongue.
  10. Loss of nasolabial and nasolacrimal fold of the affected side.
  11. Dribbling of saliva through the affected angle of the mouth.

Lesion of Facial Nerve 1

Fig: Lesion of Facial Nerve

In the lower motor type of palsy: All the facial muscles become paralyzed on the affected side.

In the upper motor type of palsy: wrinkling of the forehead is present.

Obvious features –

Facial paralysis:

  • Supranuclear “central” lesions spare the forehead and brow
  • Peripheral lesions take out the whole hemiface

Subtle features:

  • Failure of lacrimation
  • Failure of salivation
  • Loss of taste in the anterior 2/3rds of the tongue.
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