Cranial Nerve Lecture

Question 1

sensory innervation of anterior 2/3 of tongue

Answer 1

lingual n.

Question 2

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

Answer 2

glossopharyngeal n.

Question 3

CN VII somatic motor component

Answer 3

internal acoustic meatus –> emerges from stylomastoid foramen

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

Question 4

CN VII parasympathetic component

Answer 4

1. intermediate n. –> internal acoustic meatus –> facial canal –> greater petrosal n. –> vidian canal –> pterygopalatine ganglion –> glands in eye, nose, palate
2. intermediate n. –> chorda tympani (exits petrotympanic fissure, travels along V3 lingual n, synapses in submandibular ganglion, innervates submandibular and sublingual salivary glands)

Question 5

CN VII special sensory component

Answer 5

taste fibers return from anterior 2/3 of tongue

traveling back through petrotympanic fissure

encounter geniculate ganglion and return to CNS

taste buds –> lingual n –> [petrotympanic fissure] –> chorda tympani –> geniculate ganglion –> CNS

Question 6

CN V somatic sensory component

Answer 6

from trigeminal ganglion
V1 –> ophthalmic division [superior orbital fissure –> supraorbital foramen]
-nasal cavity, paranasal sinuses, meninges

V2 –> maxillary division [foramen rotundum –> infraorbital foramen]
-nasal cavity, paranasal sinuses, maxillary teeth, oral mucosa

V3 –> mandibular division [foramen ovale –> mental foramen]
-tongue (ant 2/3), lower teeth, oral mucosa, external tympanic membrane, buccal mucosa, meninges

Sensory to most of dura mater

Question 7

CN V somatic motor component

Answer 7

V3 (mandibular division) –>

4 m. of mastication
(temporalis, masseter, medial/lateral pterygoid)

4 accessory n. of mastication
(tensor tympani, myelohyoid, ant belly of digastric, tensor veli palatini)

Question 8

CN IX somatic motor component

Answer 8

thru jugular foramen to stylopharyngeus m.

Question 9

CN IX somatic sensory component

Answer 9

thru jugular foramen to back of pharynx (gag reflex)

Question 10

CN IX visceral sensory component

Answer 10

thru juglar foramen to carotid body/carotid sinus

Question 11

CN IX special sensory component

Answer 11

thru jugular foreman to posterior 1/3 of tongue

taste and general sensory

Question 12

CN IX visceral motor component

Answer 12

thru jugular foramen –> tympanic canaliculus “tympanic n.” –> forms plexus in middle ear –> emerges 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 13

CN III somatic motor component

Answer 13

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 14

CN III visceral motor component

Answer 14

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

Question 15

CN X visceral motor component

Answer 15

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

Question 16

CN X somatic motor component

Answer 16

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

Question 17

CN X special sensory component

Answer 17

jugular foramen –> to epiglottis (taste buds)

Question 18

CN X somatic sensory component

Answer 18

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

Question 19

CN I

Answer 19

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 20

olfactory tract

Answer 20

extension of the brain.

covered by meninges.

Question 21

CN II

Answer 21

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 22

optic n. vs optic tract

Answer 22

globe –> chiasm = optic n.

posterior to chiasm = optic tract

Question 23

axons of retinal ganglion cells make up the

Answer 23

optic n.

Question 24

CN IV

Answer 24

trochlear n.

somatic motor only.

devoted to one m. in eye (superior oblique m.)

Question 25

CN VI

Answer 25

abducent n.

somatic motor only.

devoted to one m. in eye
(lateral rectus m. –> moves eye LATERALLY)

Question 26

CN IV and CN VI are _____ motor only

Answer 26

SOMATIC motor only.

Question 27

CN III
CN IV
CN VI

all enter thru …

Answer 27

superior orbital fissure

between greater and lesser wings of sphenoid bone

Question 28

CN XI

Answer 28

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 29

CN XII

Answer 29

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 30

palatoglossus m. innervation

Answer 30

CN X

Question 31

genioglossus m. originates from

Answer 31

genial tubercles

Question 32

CN VIII

2 nerves?

Answer 32

vestibulochoclear n.

enters internal acoustic meatus and splits into 2 divisions, both special sensory.

vestibular division –> balance
cochlear division –> hearing

Question 33

CN VIII

path of cochlear division

Answer 33

enter internal acoustic meatus –> anterior toward cochlea for hearing

Question 34

CN VIII

path of vestibular division

Answer 34

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

Question 35

eye movement via oculomotor n. vs abducent n.

Answer 35

oculomotor n. –> most actions of eye

abducent n. –> specifically abduction (lateral movement of eye)