Cranial Nerve Lecture

Question 1

sensory innervation of anterior 2/3 of tongue

Answer 1

lingual n. (br. of V3)

Question 2

taste sensation of anterior 2/3 of tongue

Answer 2

chorda tympani n.

Question 3

general sensation and taste innervation of posterior 1/3 of tongue

Answer 3

glossopharyngeal n. (CN IX)

Question 4

CN VII somatic motor component

Answer 4

enters internal auditory meatus –> facial canal of temporal bone –> emerges from stylomastoid foramen

innervates facial muscles + stylohyoid, posterior belly of digastric, stapedius

Question 5

CN VII parasympathetic component

Answer 5

1. intermediate n. –> greater petrosal n. (to pterygopalatine ganglion, glands in eye, nose, palate)
2. intermediate n. –> chorda tympani (to submandibular ganglion, sublingual and submandibular salivary glands in oral cavity)

Question 6

CN VII special sensory component

Answer 6

taste fibers return from anterior 2/3 of tongue via piggybacking lingual n. (V3)

travels back through petrotympanic fissure w/ chorda tympani

encounter geniculate ganglion and return to CNS

Question 7

CN V somatic sensory component

Answer 7

from trigeminal ganglion
V1 –> ophthalmic division
V2 –> maxillary division
V3 –> mandibular division

Question 8

CN V somatic motor component

Answer 8

V3 (mandibular division) –>

4 m. of mastication
4 accessory n. of mastication

Question 9

CN IX somatic motor component

Answer 9

thru jugular foramen to stylopharyngeus m.

Question 10

CN IX somatic sensory component

Answer 10

thru jugular foramen to back of pharynx (gag reflex)

Question 11

CN IX visceral sensory component

Answer 11

thru juglar foramen to carotid body/carotid sinus

Question 12

CN IX special sensory component

Answer 12

thru jugular foreman to posterior 1/3 of tongue

taste and general sensory

Question 13

CN IX visceral motor component

Answer 13

thru jugular foramen –> tympanic canaliculus “tympanic n.” –> forms plexus in middle ear –> emerges from middle ear as LESSER PETROSAL N. …

thru foramen ovale –> synapses on OTIC ganglion –> postganglionic fibers of lesser petrosal n. piggyback on AURICULOTEMPORAL n. (V3) –> jump off to supply PAROTID gland

Question 14

CN III somatic motor component

Answer 14

oculomotor nucleus –> orbit –> split to sup/inf divisions –> supply 5 of 7 extraocular m.

superior rectus
inferior rectus
medial rectus
inferior oblique
levator palpebrae superioris

Question 15

CN III visceral motor component

Answer 15

accessory oculomotor nucleus –> orbit –> inferior division CN III –> ciliary ganglion –> supply ciliary m. and sphincter pupillae

Question 16

CN X visceral motor component

Answer 16

jugular foramen 
--> to glands and smooth muscle in...
larynx
pharynx
esophagus
abd viscera

–> to HEART

Question 17

CN X somatic motor component

Answer 17

jugular foramen –> to…
pharyngeal constrictors
laryngeal m.
palatal m.

Question 18

CN X special sensory component

Answer 18

jugular foramen –> to epiglottis (taste buds)

Question 19

CN X somatic sensory component

Answer 19

jugular foramen –> to…
ear/canal
LARYNX (via superior/recurrent laryngeal n.)
dura

Question 20

CN I

Answer 20

olfactory n.
special sensory only.

does NOT originate in brain stem.
originates in nose.

olfactory axons –> cribriform plate –> synapse on olfactory bulb of olfactory tract

Question 21

olfactory tract

Answer 21

extension of the brain.

covered by meninges.

Question 22

CN II

Answer 22

optic n. (extension of brain, covered by meninges)

light stim retina –> APs travel down optic n. –> some cross at optic chiasm, others don’t –> travel down “optic TRACT” –> occipital lobe for interpretation by visual cortex

Question 23

optic n. vs optic tract

Answer 23

globe –> chiasm = optic n.

posterior to chiasm = optic tract

Question 24

axons of retinal ganglion cells make up the

Answer 24

optic n.

Question 25

CN IV

Answer 25

trochlear n. somatic motor only. devoted to one m. in eye (superior oblique m.)

Question 26

CN VI

Answer 26

abducent n. somatic motor only. devoted to one m. in eye (lateral rectus m. --> moves eye LATERALLY)

Question 27

CN IV and CN VI are _____ motor only

Answer 27

SOMATIC motor only.

Question 28

CN IIII CN IV CN VI CN V(V1) all enter thru ...

Answer 28

superior orbital fissure | between greater and lesser wings of sphenoid bone

Question 29

CN XI

Answer 29

spinal accessory n. (imposter, does NOT arise from brain stem) somatic motor to SCM and trapezius. fibers from spinal nuclei --> foramen magnum --> U-turn out through jugular foramen --> to SCM and trapezius

Question 30

CN XII

Answer 30

hypoglossal n. somatic motor only to tongue. rootlets emerge from groove between pyramids/olive of medulla oblongata --> exits skull through hypoglossal canal --> innervates... genioglossus hyoglossus stylglossus

Question 31

palatoglossus m. innervation

Answer 31

CN X

Question 32

genioglossus m. originates from

Answer 32

genial tubercles

Question 33

CN VIII | 2 nerves?

Answer 33

vestibulochoclear n. enters internal acoustic meatus and splits into 2 divisions, both special sensory. vestibular division --> balance cochlear division --> hearing

Question 34

CN VIII | path of vestibular division

Answer 34

enter internal acoustic meatus --> anterior toward cochlea for hearing

Question 35

CN VIII | path of cochlear division

Answer 35

enter internal acoustic meatus --> back toward semicircular canals for balance

Question 36

eye movement via oculomotor n. vs abducent n.

Answer 36

oculomotor n. --> most actions of eye | abducent n. --> specifically abduction (lateral movement of eye)

Question 37

postganglionic fibers of greater petrosal n. to the ORBIT piggyback on ____ n.

Answer 37

postganglionic fibers of greater petrosal n. to the orbit piggyback on V1 and V2 n.

Question 38

postganglionic fibers of greater petrosal n. to the PALATE AND NOSE piggyback on ____ n.

Answer 38

postganglionic fibers of greater petrosal n. to the PALATE AND NOSE piggyback on V2 n.

Question 39

From where does the intermediate n. originate?

Answer 39

superior salivatory nucleus

Question 40

Path of intermediate n. to glands of eye

Answer 40

``` intermediate n. --> internal acoustic meatus --> facial canal --> genu --> fwd direction, "greater petrosal n." --> crosses foramen lacerum --> vidian canal --> pterygopalatine fossa --> in orbit, piggybacks on V1 and V2 --> synapses on pterygopalatine ganglion ```

Question 41

Path of intermediate n. to hard and soft palate

Answer 41

``` intermediate n. --> internal acoustic meatus --> facial canal --> genu --> fwd direction, "GREATER PETROSAL N." --> crosses foramen lacerum --> vidian canal --> pterygopalatine fossa --> piggyback on V2 --> V2 synapses on pterygopalatine ganglion--> postganglionic fibers go to nose, or through palatine canal to hard and soft palate ```

Question 42

Path of intermediate n. to salivary glands

Answer 42

``` intermediate n. --> internal acoustic meatus --> facial canal --> genu --> path thru temporal bone, "CHORDA TYMPANI N." --> middle ear --> petrotympanic fissure --> submandibular ganglion in oral cavity --> post ganglionic fibers to salivary glands ```

Question 43

vidian canal

Answer 43

from foramen lacerum in the middle cranial fossa to the pterygopalatine fossa

Question 44

V1 dermatome

Answer 44

(ophthalmic division) nasal cavity paranasal sinuses meninges

Question 45

V2 dermatome

Answer 45

(maxillary division) ``` nasal cavity paranasal sinuses meninges hard/soft palate maxillary teeth/oral mucosa ```

Question 46

greater petrosal n. vs. lesser petrosal n.

Answer 46

greater petrosal n. --> piggybacks w/ CN VIII to EYES/NOSE/PALATE lesser petrosal n. --> piggybacks w/ CN IX to PAROTID gland