Cranial Nerves

Question 1

cranial nerves

Answer 1

nerves that exit from the brain to transmit information to/from the brain

Question 2

are cranial nerves part of the CNS or PNS

Answer 2

PNS

exceptions: CN I and II

Question 3

where do most cranial nerves exit

Answer 3

ventral brainstem

exception: CN I and II (enter brain)

Question 4

skull foramina

Answer 4

openings in the skull that allow passage of cranial nerves and vessels

Question 5

extraocular muscles

Answer 5

muscles attached to the eye that are involved in eye movement

1. dorsal rectus
2. ventral rectus
3. lateral rectus
4. medial rectus
5. dorsal oblique
6. ventral oblique
7. retractor bulbi

Question 6

dorsal rectus

Answer 6

moves eye upward

Question 7

ventral rectus

Answer 7

moves eye downward

Question 8

lateral rectus

Answer 8

moves eye to the outside (away from nose)

Question 9

medial rectus

Answer 9

moves eye to the inside (toward nose)

Question 10

retractor bulbi

Answer 10

pulls eye back into socket

Question 11

strabismus

Answer 11

misalignment of the eye

Question 12

CN I

Answer 12

olfactory nerve
(NOT an actual nerve - bundle of sensory nerve fibers)

Question 13

CN I function

Answer 13

afferent: special sense of smell
has olfactory receptors in nasal epithelium

Question 14

CN I exit

Answer 14

olfactory bulb –> cribriform plate –> nasal epithelium

Question 15

CN II

Answer 15

optic nerve
(NOT an actual nerve - bundle of sensory nerve fibers)

Question 16

CN II function

Answer 16

afferent: supplies visual information
has rods/cones (receptors) in the retina

Question 17

CN II entry

Answer 17

optic canal
enters cranial vault (NOT exit)

Question 18

CN III

Answer 18

oculomotor nerve

Question 19

CN III function

Answer 19

efferent: motor to 4 extraocular muscles (DR, VR, MR, VO) and lifts eyelid
parasympathetic: pupil constriction

Question 20

CN III exit

Answer 20

orbital fissure

Question 21

CN IV

Answer 21

trochlear nerve

Question 22

CN IV function

Answer 22

efferent: motor to 1 extraocular muscle (contralateral DO)

Question 23

CN IV exit

Answer 23

orbital fissure

exits brainstem dorsally

Question 24

CN V

Answer 24

trigeminal nerve

Question 25

CN V function

Answer 25

afferent: sensory to face efferent: motor to muscles of mastication

Question 26

branches of CN V

Answer 26

1. ophthalmic (afferent) 2. maxillary (afferent) 3. mandibular (efferent)

Question 27

CN V exits

Answer 27

ophthalmic: orbital fissure maxillary: round/rostral alar foramen mandibular: oval foramen

Question 28

CN VI

Answer 28

abducens nerve

Question 29

CN VI function

Answer 29

efferent: motor to 2 extraocular muscles (LR, RB)

Question 30

CN VI exit

Answer 30

orbital fissure

Question 31

CN VII

Answer 31

facial nerve

Question 32

CN VII function

Answer 32

afferent: special sense of taste, sensory to inner pinna efferent: motor to muscles of facial expression parasympathetic: salivary and lacrimal glands

Question 33

CN VII exit

Answer 33

stylomastoid foramen

Question 34

CN VIII

Answer 34

vestibulocochlear nerve

Question 35

CN VIII function

Answer 35

afferent: sensory for hearing and balance

Question 36

CN VIII exit

Answer 36

internal acoustic meatus exits cranial cavity NOT skull

Question 37

CN IX

Answer 37

glossopharyngeal nerve

Question 38

CN IX function

Answer 38

afferent: sensory and taste to upper pharynx and caudal 1/3 of tongue efferent: motor to muscles of the pharynx parasympathetic: visceral sensory information (BP, pCO2, blood pH), parotid and zygomatic salivary glands

Question 39

CN IX exit

Answer 39

jugular/tympano-occipital foramen

Question 40

CN X

Answer 40

vagus nerve

Question 41

CN X function

Answer 41

afferent: sensory to pharynx, back of ear, external meatus, taste to epiglottis efferent: motor to muscles of the pharynx and most of larynx parasympathetic: visceral sensory functions (decrease HR, increase bronchoconstriction, increase GI secretion/motility)

Question 42

CN X exit

Answer 42

jugular/tympano-occipital foramen

Question 43

CN XI

Answer 43

accessory nerve

Question 44

CN XI function

Answer 44

efferent: motor to muscles of larynx and esophagus, neck, and shoulders

Question 45

CN XI exit

Answer 45

jugular/tympano-occipital foramen cranial and spinal roots split but both exit at same opening

Question 46

CN XII

Answer 46

hypoglossal nerve

Question 47

CN XII function

Answer 47

efferent: motor to intrinsic (some extrinsic) muscles of the tongue

Question 48

CN XII exit

Answer 48

hypoglossal foramen

Question 49

afferent only cranial nerves

Answer 49

CN I - olfactory CN II - optic CN VIII - vestibulocochlear

Question 50

efferent only cranial nerves

Answer 50

CN III - oculomotor CN IV - trochlear CN VI - abducens CN XI - accessory CN XII - hypoglossal

Question 51

mixed cranial nerves

Answer 51

CN V - trigeminal CN VII - facial CN IX - glossopharyngeal CN X - vagus

Question 52

cranial nerves with parasympathetic fibers

Answer 52

CN III - oculomotor CN VII - facial CN IX - glossopharyngeal CN X - vagus

Question 53

CN III (oculomotor) deficits

Answer 53

mydriasis ventro-lateral strabismus drooping eyelid

Question 54

CN IV (trochlear) deficits

Answer 54

difficult to assess rotation best seen in animals with vertical/horizontal pupils

Question 55

CN VI (abducens) deficits

Answer 55

medial strabismus

Question 56

CN VII (facial) deficits

Answer 56

droopy face

Question 57

CN XII (hypoglossal) deficits

Answer 57

paralysis/paresis or atrophy of the tongue muscles

Question 58

CN V: ophthalmic branch function

Answer 58

sensory to upper part of face, dorsal nasal cavity, majority of eye and associated structures

Question 59

CN V: maxillary branch function

Answer 59

sensory to lower eyelid, lateral skin around eyes, nasal mucosa, upper teeth/lip/palate, and nose

Question 60

CN V: mandibular branch

Answer 60

sensory to rostral 2/3 of tongue, oral cavity, and lower face/teeth motor to muscles of mastication, opens auditory tube

Question 61

CN V (trigeminal) deficits

Answer 61

ophthalmic: corneal ulcers due to loss of protective mechanism mandibular: open jaw, head muscle atrophy

Question 62

salivation nerve pathway

Answer 62

afferent: CN VII (taste) efferent: CN VII via chorda tympani nerve (parasympathetic)