Facial Nerve

Question 1

what is the foramen that the facial nerve comes out of?

Answer 1

stylomastoid foramen

Question 2

the facial nerve provides motor function to what muscles?

Answer 2

• muscles of facial expression
• posterior belly of digastric
• stylohyoid
• stapedius

Question 3

what are the muscles of facial expression?

Answer 3

• frontal belly of occipitofrontalis
• orbicularis oculi
• orbicularis oris
• zygomaticus major
• zygomaticus minor
• levator labii
• depressor labii
• baccinator
• platysma

Question 4

the facial nerve provides sensation from what area and what CN’s does it overlap with?

Answer 4

• small area of skin near the external auditory meatus
• V, IX and X

Question 5

the facial nerve provides special sensation of taste from ?

Answer 5

anterior 2/3 of the tongue via the chorda tympani

Question 6

where is the facial motor nucleus located and where does it exit??

Answer 6

• located in the pons and loops around the abducens nucleus before exiting at the pontomedullary junction

Question 7

what is the intracranial course of the facial nerve?

Answer 7

transverses the posterior cranial fossa to pass through the internal acoustic meatus

Question 8

is the CN VII nucleus and fascicles exiting at the pontomedullary junction a LMN or UMN?

Answer 8

lower motor neuron

Question 9

what is the CN VII motor pathway?

Answer 9

UMN: primary motor cortex —-> corona radiata —–> internal capsule ——> crus cerebri ——> terminates in pons at facial nucleus

LMN: facial nuclei —-> facial nerve

Question 10

what is the difference between the UMN for the upper and lower face?

Answer 10

• UMN to the nuclei for UPPER face have BILATERAL projections
• UMN to the nucleus for the LOWER face have CONTRALATERAL projections

Question 11

what would happen with an upper motor neuron lesion (stroke)?

Answer 11

will spare the forehead but loss of facial expression on lower face of opposite side of lesion

Question 12

what would happen with an lower motor neuron lesion (Bells Palsy)?

Answer 12

cause facial drooping on entire ipsilateral side aka complete facial paralysis

Question 13

what are the two ganglion for the parasympathetics of the facial nerve?

Answer 13

pterygopalatine ganglion and submandibular ganglion

Question 14

what is the PREganglionic parasympathetic secretomotor pathway for the facial nerve?

Answer 14

pontomedullary junction —-> posterior cranial fossa —-> internal acoustic meatus (facial canal) —-> split:

greater petrosal nerve ——-> pterygopalatine ganglion —-> lacrimal/nasal/palatine glands

and/or

chorda tympani —–> lingual nerve —–> submandibular ganglion —–> submandibular/sublingual glands

Question 15

where is the facial canal located?

Answer 15

petrous portion of the temporal bone

Question 16

what other CN is in close proximity to the facial canal and what other defects might you expect?

Answer 16

CN VIII, hearing loss and dizziness

Question 17

what would a lesion/stroke in the dorsal medial pons cause?

Answer 17

damage to the abducens nucleus and the fascicles of the facial nucleus leading to ipsilateral loss of CN VI and VII function