Brainstem and CN III, IV, VI

Question 1

abducens nerve

Answer 1

lateral rectus

Question 2

trochlear nerve

Answer 2

superior oblique

Question 3

oculomotor nerve

Answer 3

medial rectus
superior rectus
inferior rectus
inferior oblique

Question 4

axons of VII

Answer 4

loop around nucleus for CN VI (abducens)

Question 5

CN VI exits skull

Answer 5

superior orbital fissure

Question 6

CN VI innervates

Answer 6

ipsilateral lateral rectus

Question 7

lesion to abducens

Answer 7

ipsilateral loss of lateral rectus

ALSO:
facial motor nuclei has bend around the abducens
-therefore, ipsilateral facial nerve deficits

Question 8

trochlear nerve

Answer 8

axons exit dorsal
**only one doing this

-LMNs decussate**

Question 9

do trochlear nerve decussate

Answer 9

yes

LMN do decussate

Question 10

trochlear nerve innervation

Answer 10

contralateral superior oblique mm.

Question 11

oculomotor

Answer 11

extraocular mm

levator palpebrae superioris

PS supply to iris and ciliary mm

Question 12

pupil constriction

Answer 12

parasympathetic

protect from light AND increase acuity

Question 13

pupil dilation

Answer 13

sympathetic

Question 14

course of oculomotor nerve

Answer 14

goes out interpeduncular fossa

IPSILATERAL

Question 15

interpeduncular fossa nerve

Answer 15

oculomotor

Question 16

edinger westphal nucleus

Answer 16

preganglionic PS

-terminate in ciliary ganglion

Question 17

pupil reflex

Answer 17

afferent - CN II to bilateral pretectal nuclei

posterior commisure to edinger westphal

efferent - CN III out to pupillary sphincter

Question 18

why do we need an accurate visual system

Answer 18

• phototransduction slow
• fovea is small

need to foveate objects
-keep them from moving across too quickly

-also, have binocular, so need to coordinate both eyes together

Question 19

alignment of eyes requires

Answer 19

• move both eyes same direction (conjugate)

- move objects opposite direction (vergence)

Question 20

conjugate movement

Answer 20

eyes same direction

Question 21

vergence movement

Answer 21

eyes opposite direction

Question 22

voluntary movements involve?

Answer 22

UMNs - in cortex
-to basal ganglia and cerebellum

LMNs - to CN III, IV, VI
-no direct corticobulbar innervation

Question 23

systems that keep object on fovea

Answer 23

1 saccades
2 smooth pursuit
3 vergence

Question 24

systems that stabilize retinal image

Answer 24

1 vestibuloocular movement

2 optokinetic movements

Question 25

saccades

Answer 25

fast, redirect gaze

Question 26

smooth pursuit

Answer 26

keep object on fovea | -requires a visual target

Question 27

what requires visual target

Answer 27

smooth pursuit

Question 28

conjugate movements

Answer 28

saccads | smooth pursuit

Question 29

fast phase of nystagmus

Answer 29

saccades | -redirect gaze

Question 30

CNS ignores input?

Answer 30

during a saccade

Question 31

frontal eye fields

Answer 31

BA 6 and 8 - contralateral to paramedian pontine reticular formation (PPRF) - also to rostral interstitial nucleus of the MLF - also to superior colliculus

Question 32

rapid horizontal gaze

Answer 32

PPRF - to ipsi abducens - to contra oculomotor

Question 33

rapid vertical gaze

Answer 33

to riMLF | -bilateral

Question 34

input to frontal eye field

Answer 34

supplementary motor | parietal eye field

Question 35

superior colliculus

Answer 35

visual grasp reflex

Question 36

location of frontal eye field

Answer 36

anterior to facial of primary motor cortex

Question 37

something moving in periphery

Answer 37

parietal eye field to frontal eye field

Question 38

supplementary eye field

Answer 38

looking at sequence | -like down totem pole

Question 39

PPRF projections

Answer 39

to CN III, IV, VI via MLF

Question 40

left cortex

Answer 40

controls rightward gaze and vice versa saccades

Question 41

smooth pursuit

Answer 41

requires visual target - keep target on fovea - calculates vector (speed and direction) slower

Question 42

use of flocculus

Answer 42

smooth pursuit | -uses cerebellum

Question 43

smooth pursuit circuit

Answer 43

FEF > pontine nuclei > flocculus > vestibular nuclei > MLF > motor nuclei of III, IV, VI

Question 44

difference between smooth pursuit and VOR

Answer 44

the afferent info smooth pursuit - visual target VOR - vestibular apparatus about acceleration

Question 45

convergence

Answer 45

eyes toward midline | -medial rectus mm.

Question 46

stimulus for convergence

Answer 46

retinal disparity (objects out of focus) too close - converge

Question 47

close object

Answer 47

loss of focus - drives accommodation - CN III also - pupillary constriction occurs -increasing acuity

Question 48

occurs during convergence

Answer 48

accommodation of lens | pupillary constriction

Question 49

near triad

Answer 49

convergence accommodation pupil constriction

Question 50

circuits of vergence

Answer 50

FEF to reticular formation in rostral midbrain adjacent to CN III

Question 51

VOR

Answer 51

move eye in response to acceleration

Question 52

optokinetic system

Answer 52

active during continuous velocity -with no acceleration REFLEXIVE

Question 53

what are optokinetic movement

Answer 53

oscillatory eye movement in response to steady velocity smooth pursuit alternating with saccades

Question 54

watching a train passing

Answer 54

optokinetic movement

Question 55

circuit to optokinetic

Answer 55

motion sensitive ganglion cells > accessory optic nuclei > vestibular nuclei > MLF > motor nuclei of III, IV, VI