SM_27b: Overview of the Cranial Nerves: VII and VIII

Question 1

Facial nerve enters the ____ of the ____ of the temporal bone

Answer 1

Facial nerve enters the internal acoustic meatus of the petrous part of the temporal bone

Question 2

Facial nerve (VII) divides into three branches within the temporal bone: ____, ____, and ____

Answer 2

Facial nerve (VII) divides into three branches within the temporal bone

• Greater petrosal: parasympathetics to V2
• Chorda tympani (out of petrotympanic fissue) with taste and parasympathetics to V3
• Facial nerve proper out stylomastoid foramen to muscles (branchiomotor)

Question 3

Greater petrosal division of facial nerve provides ____

Answer 3

Greater petrosal division of facial nerve provides parasympathetics to V2

Question 4

Chorda tympani division of facial nerve provides ____ and ____ for V3

Answer 4

Chorda tympani division of facial nerve provides taste and parasympathetics to V3

(anterior 2/3 of tongue)

Question 5

Facial nerve proper is ____ to the face muscles

Answer 5

Facial nerve proper is branchiomotor to the face muscles

Question 6

Nevus intermedius is ____

Answer 6

Nevus intermedius is smaller root of VII for taste and parasympathetic fibers in between the larger branchiomotor root and the vestibulocochlear nerve

Question 7

Describe facial nerve distribution

Answer 7

Facial nerve distribution

• Temporal, zygomatic, buccal, mandibular, and cervical nerves are more geographic territories than specific facial nerve branches
• All within substance of parotid gland

Question 8

Depressor anguli oris goes to ____, while depressor labii inferioris goes to ____

Answer 8

Depressor anguli oris goes to angle, while depressor labii inferioris goes to lower lip

Question 9

Bell’s Palsy affects the ___ nerve and often results from ___

Answer 9

Bell’s Palsy affects the facial nerve and often results from Herpes infection

• Have patient make a face to contract muscles -> expressionless on affected side
• Cannot close eye, hard to keep food / liquid in mouth (orbicularis oris / buccinator lost on affected side)
• Taste and lacrimal gland may also be affected

Question 10

____ is pretrematic branch for facial nerve

Answer 10

Chorda tympani is pretrematic branch for facial nerve

Question 11

Vestibulocochlear nerve (VIII) exits through ____ of ____ part of temporal bone

Answer 11

Vestibulocochlear nerve (VIII) exits through internal acoustic meatus of petrous part of temporal bone

Question 12

Auditory / Eustachian tube leads from the ____ to ____

Answer 12

Auditory / Eustachian tube leads from the pharynx to middle ear

Question 13

Cochlear nerve division of CN VIII goes to ____ for ____

Answer 13

Cochlear nerve division of CN VIII goes to cochlea for hearing

Question 14

Vestibular nerve division of CN VIII goes to ____ for ____

Answer 14

Vestibular nerve division of CN VIII goes to vestibular apparatus (semicircular canals) for sense of balance and motion

Question 15

Primordium of vestibulocochlear nerve (VIII) is ____

Answer 15

Primordium of vestibulocochlear nerve (VIII) is otic placode (ectoderm)

• Otic placode sinks under the surface to form the otocyst, which is the primordium for the inner ear

Question 16

Otocyst forms the ____ and shapes into the ____ and ____

Answer 16

Otocyst forms the inner ear and shapes into the cochlea and semicircular canals