Facial nerve

7) 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	The part of the nucleus that supplies the upper part of the face receives corticonuclear fibers from both cerebral hemispheres 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	Afferents from the thalamus through descending autonomic pathway Afferents regarding taste via nucleus of the solitary tract from the mouth
Parasympathetic nucleus	Lacrimal nucleus	Afferents from hypothalamus for emotional response 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

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