20.7 NS: Cranial nerves 2

Question 1

Where do CN I and II exit the skull?

Answer 1

I: Cribiform plate
II: Optic canal (within sphenoid)

Question 2

After axons of CN II cross within the optic chiasm, where do they travel?

Answer 2

To lateral geniculate nucleus within thalamus (then to visual cortex)

Question 3

Where do the nerves to the extraocular muscles exit the skull?

Answer 3

Superior orbital fissure (between greater and lesser wings of sphenoid)

Question 4

Which muscles are controlled by CN III? What is the action? What is its visceral motor action?

Answer 4

CN III:
Extraocular muscles: MR, SR, IR, IO

elevates eyelid (levator palpebrae superioris)

PS to eye, pupils and ciliary muscle

Question 5

Which cranial nerves exit the auditory canal?

Answer 5

CNVII, VIII

Question 6

Which cranial nerves (and vein) exit the jugular foramen?

Answer 6

CNIX, X, XI and internal jugular vein

Question 7

Where does CNXII exit?

Answer 7

Hypoglossal foramenh

Question 8

Which CNs exit the superior orbital fissure?

Answer 8

CNIII, IV, VI, V1

Question 9

What CN innervates Sphincter Pupillae? Which nucleus do these PS fibres come from?

Answer 9

CNII

PS fibres from Edinger Westfal nucleus

Question 10

What does the trigeminal nerve do?

Answer 10

Sensory face

Motor: muscles of mastication and tensor tympani

Question 11

Where do the trigeminal nuclei run?

What nuclei do they consist of?

Answer 11

Midbrain to upper spinal cord

Mesencephalic, chief sensory, spinal trigeminal nucleus (STN), motor nucleus

Question 12

What are the divisions of the trigeminal nerve and where do they exit?

Answer 12

V1: Ophthalmic (SOF)
V2: Maxillary (foramen rotundum)
V3: Mandibular (foramenb ovale)

Question 13

What can we use to test midbrain function?

What can we use to test pontine function?

Medulla function?

Answer 13

Pupillary light reflex

Corneal blink reflex

Gag reflex

Question 14

What innervates the stapedius muscle? What does this muscle do?

Answer 14

VII, protects ear from loud noises

Question 15

What PS, taste and sensation innervation does CN VII provide?

Answer 15

PS: lacrimal, sublingual, submandibular salivary glands

Taste: anterior 2/3rds tongue, soft palate

Sensation: small region next to external auditory meatus

Question 16

What are the terminal branches of the facial nerve?

Answer 16

Temporal
Zygomatic
Buccal
Mandibular
Cervical

Question 17

What are the order from the brainstem onwards of the divisions of the facial nerve

Answer 17

Greater petrosal
Branch to stapedius
Chorda tympani
Posterior auricular

Terminal branches (TZBMC)

Question 18

Where does VIII exit the skull?

Answer 18

Internal acousitc meatus

Question 19

What are the nuclei at the brainstem for the vestibulocochlear nerve?

Answer 19

Dorsal, ventral cochlear nuclei

Four vestibular nuclei

Question 20

Where does CNIX exit the skull?

What does it do? (Sensory, taste, motor)

Answer 20

Jugular foramen

Sensory from tongue (post 1/3), pharynx, middle ear, carotid body
Taste: post 1/3 tongue
Motor: stylopharyngeus

Question 21

What are the sensory/motor inputs and outputs for the gag reflex?

Answer 21

Sensory: IX to pharynx
Motor: X to pharynx

Question 22

What does XI do?

Where is the nucleus? Where does it enter and exit

Answer 22

Shrugs shoulders, turns head

Nucleus in upper 5-6 of C

Enters: via foramen magnum

Exits: jugular foramen

Question 23

What does hypoglossal innervate?

Answer 23

Muscles of tongue (except palatoglossus-CNX)

Question 24

What are the exceptions of nuclei that receive input or provide output to one CN?

Answer 24

Solitarius
Ambiguus
Trigeminal