Cranial Nerves

Question 1

CN I

Answer 1

olfactory nerve

Question 2

function of CN I

Answer 2

olfactory nerve

sensory only
- detects odors

Question 3

clinical significance of CN I

Answer 3

cribriform plate abnormalities can cause issues with this nerve

Question 4

CN II

Answer 4

optic nerve

Question 5

function of CN II

Answer 5

optic nerve

sensory only

night vision + lights + color

Question 6

clinical significant of CN II

Answer 6

optic foramina development depends on vA in calves

Question 7

CN III

Answer 7

oculomotor nerve

Question 8

function of CN III

Answer 8

oculomotor nerve

motor only
innervates
- dorsal, medial, ventral rectus muscles
- levator palpebrae

parasympathetic innervation of pupillary constrictors

Question 9

clinical significance of CN III

Answer 9

lack of function leads to ventrolateral strabismus and pupillary dilatation

Question 10

CN IV

Answer 10

trochlear nerve

Question 11

function of CN IV

Answer 11

trochlear nerve

motor only
- innervates the dorsal oblique muscle

Question 12

clinical significance of CN IV

Answer 12

isolated lesions are very rare

crosses entirely to the contralateral side

Question 13

CN V

Answer 13

trigeminal nerve

Question 14

function of CN V

Answer 14

mixed nerve

three branches

1. ophthalamic branch
   - sensory info from facial skin, nasal cavity, and around the eye
2. maxillary branch
   - sensory info from the facial skin, nasal cavity, upper teeth, and hard palate
3. mandibular branch
   - sensory info. from the rostral 2/3 of the tongue, lower jaw skin, lower teeth, cheek mucosa
   - motor info to masticatory muscles

Question 15

clinical significance of CN V

Answer 15

damage to the mandibular branch can cause issues with eating

masticatory myositis

head shaking in horses

motor neuron nuclei vacuolization in goats

Question 16

CN VI

Answer 16

abducens nerve

Question 17

function of CN VI

Answer 17

motor only

innervates

• lateral rectus
• retractor bulbi

Question 18

clinical significance of CN VI

Answer 18

damage

- cannot move eye to the side to follow something (laterally)

Question 19

CN VII

Answer 19

facial nerve

Question 20

function of CN VII

Answer 20

sensory:

• rostral 2/3 of the tongue*
• palate*
• external ear canal
• salivation reflex

motor:
- facial expressions: eyelid, ear, lips, cheek, nostrils

parasympathetic fibers
- mandibular and lingual salivary glands

Question 21

clinical significance of CN VII

Answer 21

damage

paralysis of face
- face appears pulled to the side with functioning neuron(s)

bilateral paralysis
- animal doesn’t lift ears

Question 22

CN VIII

Answer 22

vestibulocochlear

Question 23

function of CN VIII

Answer 23

sensory only

balance and hearing

only CN that doesn’t leave the skull

Question 24

clinical significance of CN VIII

Answer 24

can damage only one portion and have balance issues

Question 25

CN IX

Answer 25

glossopharyngeal

Question 26

function of CN IX

Answer 26

mixed nerve

sensory:

• caudal 1/3 of tongue
• pharynx (important for swallowing and gag reflex)

motor:
- muscles of pharynx

parasympathetic fibers
- parotid and zygomatic salivary glands

Question 27

CN X

Answer 27

vagus nerve

Question 28

function of CN X

Answer 28

mixed nerve

sensory:
- external acoustic meatus

motor:

• larynx
• pharynx
• esophagus

large parasympathetic role:

• heart
• GI tract
• resp. tract

Question 29

CN XI

Answer 29

accessory nerve

Question 30

function of CN IX

Answer 30

motor only

larynx

cleidocephalicus
trapezius

Question 31

CN XII

Answer 31

hypoglossal nerve

Question 32

function of CN XII

Answer 32

motor only

tongue

• intrinsic muscles
• hypoid apparatus: geniohyoideus, stylohyoideus, thyrohyoideus

Question 33

clinical significance of CN XII

Answer 33

loss of function results in lolling tongue

sticks out to the normal side because the affected side isn’t pulling it back