Facial Nerve

Question 1

trace the path of the facial nerve through the middle cranial fossa

Answer 1

leaves the pontomedullary junction and travels through the internal acoustic meatus. gives off the greater petrosal nerve 1st. gives off the stapedius nerve to the stapedius muscle. then gives off the chorda tympani to meet with the lingual nerve. facial nerve then exits the stylomastoid foramen and branches in the parotid to be the PA, temporal, zygomatic, buccal, mandibular, and cervical branches.

Question 2

major muscles of facial expression do…?

Answer 2

close the eyes, smile, wrinkle the forehead

Question 3

what innervates the posterior belly of the digastric?

Answer 3

CN VII

Question 4

what innervates stylohyoid?

Answer 4

CNVII

Question 5

which cranial nerves have parasympathetic innervation?

Answer 5

3, 7, 9, 10

Question 6

function of greater petrosal nerve?

Answer 6

preganglionic parasympathetic to pterygopalatine ganglion, joins with deep petrosal nerve (sympathetics) to make the nerve of the pterygoid canal (vidian)

Question 7

function of nerve to stapedius?

Answer 7

motor to stapedius muscle, protects the ear from loud noises

Question 8

function of chorda tympani?

Answer 8

taste to anterior 2/3 of tongue and parasympathetics to submandibular and sublingual glands via submandibular ganglion

Question 9

branches of facial nerve to facial expression:

Answer 9

1. temporal
2. zygomatic
3. buccal
4. marginal mandibular
5. cervical

Question 10

what would the clinical symptoms be if there was a lesion in the facial nerve right after it exited the stylomastoid foramen?

Answer 10

1. angle of mouth sags
2. drool
3. food accumulates in the mouth
4. paralysis of upper eyelid may fail to protect and lubricate cornea = ulceration
5. asymmetric smile

Question 11

what would the clinical symptoms be if there was a lesion in the facial canal at the junction of the greater petrosal nerve AKA BELLS PALSY?

Answer 11

1. angle of mouth sag, drool, paralysis of upper eyelid = ulceration of cornea, asymmetric smile (facial paralysis)
2. no taste or sense to anterior 2/3 tongue
3. decreased salivation on affected side
4. sensitivity to sound (hyperacusis)
5. reduced production of tears (dry eyes)

Question 12

what would occur if the lingual nerve was cut before its junction with the chorda tympani?

Answer 12

lose general sense to anterior 2/3 tongue – taste intact

Question 13

what would occur if the chorda tympani was cut before its junction with the lingual nerve?

Answer 13

no secretions from submandibular or sublingual glands, no taste from anterior 2/3 of tongue – general sense intact

Question 14

what would occur if the lingual and chorda tympani were cut when they joined?

Answer 14

no secretions from glands, no taste or sensation anterior 2/3 of tongue

Question 15

what occurs if there is an acoustic neuroma at the internal acoustic meatus?

Answer 15

both CN7 and CN8 would be affected.
decreased tear production (lacrimal gland), decreased glandular secretion from submandibular and sublingual glands, facial paralysis, hyperacusis AND hearing and balance deficits

Question 16

what is the motor/special visceral efferent function of the facial nerve?

Answer 16

1. supplies muscles of facial expression
2. posterior belly of digastric
3. stylohyoid
4. stapedius muscle

Question 17

what is the visceral motor/general visceral efferent function of the facial nerve?

Answer 17

1. parasympathetic innervation of lacrimal, submandibular, sublingual glands
2. mucous membranes of nasopharynx, hard palate, soft palate

Question 18

special sensory/special afferent function of facial nerve

Answer 18

taste for anterior 2/3 of tongue, hard palate, and soft palate

Question 19

general sensory/general somatic afferent function of facial nerve

Answer 19

general sensation from skin of concha of the auricle, and small area behind ear.

Question 20

where does the chorda tympani loop around in the middle ear?

Answer 20

around the long limb of the incus, and the handle of the malleus

Question 21

what is the cell body that is associated with the facial nerve?

Answer 21

geniculate ganglion

Question 22

explain the geniculate ganglion

Answer 22

parasympathetic and motor nerve fibers from CN7 travel through the geniculate ganglion but don’t synapse there. is a sensory ganglion, but doesn’t have any synapses. is like the dorsal root ganglion.