Facial Nerve: Functional Components

Functional Components:
  • Special Visceral Efferent/Branchial Motor
  • General Visceral Efferent/Parasympathetic
  • General Somatic Afferent/Sensory
  • Special Visceral Afferent/Taste
  • General Visceral Afferent/sensory from glands
Special Visceral Efferent/Branchial Motor:
  • Premotor cortex →motor cortex →corticobulbar tract→bilateral facial motor nuclei (pons) →facial muscles
  • Stapedius, stylohyoid, posterior digastric, buccinator
General Visceral Efferent/Parasympathetic:
  • The brainstem general visceral efferent column nuclear groups includes :
  1. Edinger Westphal nucleus at rostral levels of the midbrain
  2. Superior salivatory nucleus in the lower pons
  3. Inferior salivatory nucleus 
  4. Dorsal vagal nucleus in the medulla oblongata. 
Superior salivatory nucleus (pons) 
                 ↓
NervusIntermedius→ChordaTympani→joinslingualnerve→submandibular ganglion→postganglionic parasympathetic fibers→submandibular and sublingual glands
                 ↓
Greater/superficial petrosal nerve
                 ↓
Facial hiatus/middle cranial fossa
                 ↓
Joins deep petrosal nerve (symp fibers from cervical plexus)
                 ↓
Through pterygoid canal (as vidian nerve)
                ↓
Pterygopalatine fossa
                ↓
Spheno/pterygopalatine ganglion
                ↓
Postganglionic parasympathetic fibers
                ↓
Joins zygomaticotemporal nerve(V2)
                ↓
Lacrimal gland & seromucinous glands of nasal and oral cavity

  • General Somatic Afferent/Sensory
  1. Sensation to auricular concha, EAC wall, part of TMJ, postauricular skin
  2. Through Cell bodies in geniculate ganglion
  3. Proprioseptive impulsesfrom muscles of face through V C.N. to mesencephalic nucleus
  4. Special Visceral Afferent/Taste
Postcentral gyrus
        ↓
Nucleus tractus solitarius
        ↓
Nervus intermedius
        ↓
Geniculate ganglion
        ↓
Chorda tympani
        ↓
Joins lingual nerve
        ↓
Anterior 2/3 tongue, soft and hard palate

  • General Visceral Afferent/sensory from glands:
  1. Provide sensation to the soft palate and parts of the nasal cavity
  2. GVA create referred pain by activating general somatic afferent fibers where the two meet in the posterior horn of the spinal cord (dorsal horn).
  3. The general visceral afferent column is represented by part of the dorsal nucleus of the vagus nerve.
Exam Question
  • The general visceral afferent column is represented by part of the dorsal nucleus of the vagus nerve.
  • Dorsal vagal nucleus belongs to general visceral efferent component of vagus
  • Functional components of facial nerve are GSA, GVA,GVE,SVE,SVA (Facial nerve doesnot contain Somatic Efferents).
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