Facial reanimation

Question 1

Describe Frey’s Syndrome

Answer 1

• aberrant reinnervation of sweat glands by auriculotemporal N (carries sympathetic fibers to the sweat glands of the scalp & parasympathetic fibers to the parotid. If cut + inappropriate regeneration, fibers my switch courses)
• Diagnosis: minors starch iodine test
• Medical treatment: scopolamine (topical anticholinergic cream), glycopyrrolate, botox
• Surgical treatment: skin excision or interpositional flaps (dermal/fat graft, AlloDerm, SMAS, TPF, pedicled ms flap e.g. SCM)

Question 2

List muscles innervated by facial nerve that are not grouped as a muscle of facial expression

Answer 2

• stapedius
• auricularis posterior
• occipitalis
• stylohyoid
• posterior belly digastric

Question 3

what muscles of facial expression are innervated by superficial surface?

Answer 3

• buccinator
• levator anguli oris
• mentalis
• BLOAM

Question 4

Describe the intra-cranial & intra-temporal course and branches of facial nerve

Answer 4

Intracranial:

• Facial nucleus is at pons, between abducens and vestibulocochlear
• emerges from brainstem via cerebellar pontine angle
• travels alongside the nervus intermedius (sensory component)

Intratemporal

• enters petrous temporal bone at internal auditory canal
• travels w CNVIII for 8-12 (14-16mm)
• then enters the fallopian canal by itself; there are 3 segments:
• LABRYNTHINE
  
  • location of geniculate ganglion; facial n entering geniculate ganglion represents “1st turn)
  • nervus intermedius joins motor component at geniculate ganglion
  • narrowest part of intra-temporal course (most prone to injury or compression)
  • gives off greater petrosal nerve (parasymp branch to lacrimal) & other petrosal nerves
• Tympanic
  
  • horizontal, 2nd turn, no branches
• Mastoid
  
  • from tympanic cavity to stylomastoid foramen
  • gives off
    
    • nerve to stapedius (dampens noise, dysfxn = hyperacusis)
    • sensory auricular branch
    • chorda tympani: parasymp to subling/subMd & special sensory to anterior 2/3 tongue taste

Question 5

Describe the extratemporal course of the facial nerve

Answer 5

• exits stylomastoid foramen
  
  • gives posterior auricular n (auricularis posterior, occipitalis); nerve to posterior belly digastric, nerve to stylohyoid
• travels anterior to posterior belly digastric, lateral to styloid process, behind facial vein, passes through retromandibular fossa to enter the parotid
• travels between the superficial and deep lobes in parotid
• splits into temporo-facial and cervico-facial branches ~ at level of mandibular neck
• at superior/anterior/inferior margin of parotid, 5 facial nerve branches exit
• here travel deep to SMAS (but above level of parotomasseteric fascia)

Question 6

List communications the FN has with other cranial nerves:

Answer 6

1. CN V
   
   1. V1: with lacrimal nerve to lacrimal gland, parasymp innervation
   2. V2: w greater palatine to innervate nasal muscosa
   3. V3: w lingual n via chorda tympani to submandibular and sublingual glands
2. VII - interconnecting branches between buccal and zygomatic branches
3. VIII - as they leave cranial fossa to internal auditory canal
4. X - sensory innervation to EAM