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Facial nerve

7) Facial nerve
Facial nerve
Facial nerve
  • The facial nerve emerges from the anterior surface of the brain, between the pons & the MO
  • It has 3 nuclei

    • The main motor nucleus
    • The parasympathetic nuclei (Superior salivatory nucleus & Lacrimal nucleus)
    • The sensory nuclei

  • Functions

    • Motor nucleus supplies:

      • Muscles of facial expression
      • Auricular muscles
      • Stapedius muscle
      • Posterior belly of the Digastric muscle
      • Stylohyoid muscle

    • Superior salivatory nucleus

      • Sub mandibular & sub lingual glands
      • Nasal & palatine glands

    • Lacrimal nucleus : Lacrimal gland
    • Sensory nucleus : Taste fibers from,

      • Anterior 2/3 of the tongue
      • Floor of the mouth
      • Palate

Facial nerve nuclei & their connections

Main motor nuclei
  1. The part of the nucleus that supplies the upper part of the face receives corticonuclear fibers from both cerebral hemispheres
  2. The part of the nucleus that supplies the lower part of the face receives corticonuclear fibers only from the opposite cerebral hemispheres

Parasympathetic nucleus Superior salivatory nucleus
  1. Afferents from the thalamus through descending autonomic pathway
  2. Afferents regarding taste via nucleus of the solitary tract from the mouth

Lacrimal nucleus
  1. Afferents from hypothalamus for emotional response
  2. Afferents from the sensory nuclei of the TGN for reflex lacrimation 2ndry to corneal or Conjunctival irritation

Sensory nucleus This is the upper part of the nucleus of the tractus solitarius Carry the sensation of taste to the taste area of the cortex – Lower part of the post central gyrus (Through VPM nucleus of the opposite thalamus, internal capsule & corona radiata)

Examination of the facial nerve
  • Observe the patient as he talks & smiles; watch for:

    • Eye closure
    • Asymmetrical elevation of the one corner of the mouth
    • Flattening of nasalabial folds

  • Then the patient is instructed to:

    • Wrinkle the forehead (By looking upwards with still head) : Frontalis
    • Close eyes while examiner tries to open them : Orbicularis oculi
    • Purse lips while the examiner presses cheeks : Buccinator
    • Show teeth : Orbicularis oris

  • Taste : Place sugar & salt in the anterior 2/3 of the protruding tongue
Facial nerve Facial nerve Reviewed by Radiology Madeeasy on August 08, 2010 Rating: 5
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