L12 facial nerve and muscles of facial expression Flashcards
What** structures** does the** facial nerve supply**?
- motor supply to muscles of facial expression
- motor innervation to** strapedius muscle **
- sensory innervation to the** external ear**
- special sensory (taste) to anterior 2/3 of tongue
- secretomotor/ visceromotor to glands of face - submandibular, lacrimal & sublingual
what motor function does the facial nerve have relative to the strapedius muscle?
- it** prevents excess movement of stapes **(the stirrup) bone to help control amplitude of sound waves to ear
what does the** paralysis of the facial nerve** to the strapedius muscle lead to?
- leads to hyperacusis ( ie normal sounds are percirved as very loud)
where does the facial nerve arise from?
the **pontomedullary junction **(pons)
what 4 nuclei do the sensory and motor roots of the facial nerve arise from?
- solitary (taste to anterior 2/3 of tongue)
- motor (mm of face & stapedius)
- salivary
- lacrimal
from the pontomedullary junction, where does the facial nerve transverse to?
the internal auditory (acoustic ) meatus in the temporal bone
* therefore becomes a intertemporal nerve
Once the facial nerve transverses into the interal auditory meatus, what canal does it travel through?
- the** internal auditory canal**
- therefore the nerve goes from intertemporal to inter canicular
Up until what point does the facial nerve travel through the internal auditory canal?
Up until the intergenicular ganglion (also called genu)
what 1st branch does the facial nerve give off once it reaches the intergenicular ganglion?
- it gives off the **greater petrosal nerve **
what branches does the greater petrosal nerve give off?
- courses through the base of the skull, and gives rise to** palatine branches** that go to the nasal cavity and palate which supply mucous glands and membranes of those areas
- also hitchhikes the V2 and V3 branches of trigeminal nerve up to the lacrimal gland to produce tears
What other branch does the facial nerve form at the genu when it turns posteriorly in middle ear?
chorda tympani nerve
what structures does the chorda tympani innervate?
- the submandibular gland
- the **sublingal **gland
- the taste sensation of the anterior 2/3 of the tongue
what fissure does the chorda tympani nerve exit at the bottom of the skull to go near the tongue?
the **petrotymapnic fissure **
what nerve does the chorda tympani share a pathway with
- shares a pathway with lingual nerve to provide taste sensation to the anterior 2/3 of the tongue
what other branch (not chorda tympani or greater petrosal nerve) does the facial nerve give off at the genu?
the facial nerve proper
where does the facial nerve proper exit the skull?
the stylomastoid foramen - the extracranial nerve
initially what 3 branches does the facial nerve proper give off?
- post auricular nerve
- nerve to posterior belly of digastric muscle
- nerve to stylomastoid muscle
what are the key muscles of facial expression?
- frontalis
- corrugator supercilii
- orbicularis oculi
- nasalis
- buccinator
- zygomatic major
- zygomatic minor
- orbicularis **oris **
what is the function of the frontalis muscle?
- wrinkles fore head
- creates horizontal wrinkles
note it is just 2 lobe like structures at front - not the top of head
what is the function of the corrugator supercilii?
- draws eyebrows together medially and inferiorly
- creates vertical wrinkles
what is the function of the orbicularis oculi?
closes eye shut
what is the functon of the nasalis muscle?
flares nostril
what is the function of the **buccinator **muscle?
compresses and expands cheeks
eg duck face
what is the function of the zygomaticus major muscle ?
- pulls corners of mouth superolaterally when **smiling **
what is the function of the zygomaticus minor muscle?
- elevates upper lip
what is the function of the orbicularis oris muscle?
- purses lips closed
