cranial nerves

Question 1

decrease in bilateral constriction when light is shone in affected eye vs unaffected eye is due to

Answer 1

afferent pupillary defect: optic nerve damage or severe retinal injury
called a Marcus Gunn pupil

Question 2

diminshed or no pupillary light reflex in affected eye (direct and consenual) is due to

Answer 2

efferent pupillary defect: CN3 (oculomotor n.) damage due to compression from PCA aneurysm or uncal herniation

Question 3

inner part of CN 3 includes

Answer 3

motor fibers for EOM, levator palpebrae

susceptible to ischemia from diabetes: glucose → sorbitol

Question 4

outer part of CN 3 includes

Answer 4

parasympathetic fibers for pupillary light reflex

susceptible to compression

Question 5

ptosis + down + out gaze due to

Answer 5

ischemia damage to CN3 (inner part of nerve)

Question 6

lateral rectus m. innervated by

Answer 6

CN 6

Question 7

superior oblique m. innervated by

Answer 7

CN 4

Question 8

all the rest of EOM’s innervated by

Answer 8

CN 3

Question 9

what is the lesion?
eye looks down + out
ptosis
pupillary dilation 
loss of accommodation

Answer 9

CN 3 damage

Question 10

eye looks upward especially with contralateral gaze (problems going down stairs)
head tilt toward side of lesion

Answer 10

CN 4 damage

Question 11

eye looks medially

no abduction

Answer 11

CN 6 damage

Question 12

bitemporal hemianopsia due to lesion at

Answer 12

optic chiasm

Question 13

L or R homononymous hemianopsia due to lesion at

Answer 13

contralateral optic tract

Question 14

L or R anopsia due to lesion at

Answer 14

optic nerve (CN 2)

Question 15

macula lesion due to

Answer 15

macular degeneration

Question 16

L or R homonymous hemianopsia + macular sparing due to lesion at

Answer 16

contralateral PCA infarct

Question 17

nerve that provides touch to anterior 2/3 of tongue

Answer 17

mandibular branch (V3) of CN 5

Question 18

nerve that provides taste to anterior 2/3 of tongue

Answer 18

facial nerve (CN 7)

Question 19

nerve that provides touch to posterior 1/3 of tongue

Answer 19

glossopharyngeal nerve (CN 9)

Question 20

nerve that provides taste to posterior 1/3 of tongue

Answer 20

glossopharyngeal nerve (CN 9)

Question 21

nerve that provides taste to epiglottis

Answer 21

vagus nerve (CN 10)

Question 22

paralysis of ISPSILATERAL side of ENTIRE face caused by this lesion (smile droop + can’t close eye)

Answer 22

facial nerve (CN 7)/nucleus lesion (Bell’s palsy)

Question 23

paralysis of ISPSILATERAL side of ENTIRE face caused by this lesion

Answer 23

facial nerve (CN 7)/nucleus lesion (Bell’s palsy)

Question 24

paralysis of CONTRALATERAL side of LOWER face caused by this lesion

Answer 24

facial motor cortex lesion (stroke)
if able to raise forehead + eyebrows - r/o facial nerve (CN 7) palsy
facial motor cortex receives motor fibers for the LOWER face only from the CONTRALATERAL cortex but receives motor fibers for the UPPER FACE from BOTH cortices

Question 25

CONTRALATERAL uvula deviation due to lesion of

Answer 25

vagus nerve (CN 10) or nucleus ambiguus (medulla lesion)
levator veli palatini m. not elevating the palate on the side of the nerve lesion so uvula deviates in opposite direction (only side pulling up on palate)

Question 26

IPSILATERAL tongue deviation when sticking out due to lesion of

Answer 26

hypoglossal nerve (CN 12)/nucleus
"LICK THE WOUND"

Question 27

IPSILATERAL tongue deviation when sticking out due to lesion of

Answer 27

hypoglossal nerve (CN 12)/nucleus
"LICK THE WOUND" - like a wheelbarrow

Question 28

motor neurons of vagus nerve (CN 10) originate in

Answer 28

nucleus ambiguus in medulla

Question 29

functions of nucleus ambiguus

Answer 29

swallowing + speech + palate elevation

Question 30

nucleus ambiguus in medulla receives input from BOTH motor cortices via corticobulbar tracts

Answer 30

lesion in L or R motor cortex above nucleus ambiguus WON’T cause uvula deviation

Question 31

each hypoglossal nuclei receive input from BOTH motor cortices

Answer 31

lesion in L or R motor cortex above hypoglossal nuclei WON’T cause tongue deviation

Question 32

findings with cavernous sinus infection

Answer 32

CN 3: down + out eye
CN 4
CN 6: can't abduct eye
CN 5 (V1,V2): pain + numbness in face
diplopia

Question 33

findings with cavernous sinus syndrome due to infection

Answer 33

CN 3: down + out eye
CN 6: can’t abduct eye - most common (most medial)
CN 5 (V1,V2): pain + numbness in face
diplopia

Question 34

salivation of parotid gland

Answer 34

CN 9

Question 35

salivation of sublingual and submandibular gland

Answer 35

CN 7

Question 36

hypoxia measured by carotid body

Answer 36

CN 9

Question 37

blood pressure from carotid sinus

Answer 37

CN 9

Question 38

blood pressure from aortic arch

Answer 38

CN 10