ANAT control of eye movements

Question 1

Saccadic

supranuclear gaze control systems

Answer 1

rapid eye movement that brings image of object onto the fovea
conjugate movement

Question 2

smooth pursuit

supranuclear gaze control systems

Answer 2

keeps a moving image centered on fovea

conjugate movement

Question 3

vestibular-ocular

supranuclear gaze control systems

Answer 3

hold image steady on fovea during head movements

conjugate movement

Question 4

vergence

supranuclear gaze control systems

Answer 4

keep image on fovea when object is moving close/far away

disconjugate movement

Question 5

what CNs are involved in the horizontal saccadic system
what is the horizontal gaze center
pathway

Answer 5

CN6 nucleus
CN3 nucleus

(PPRF – horizontal gaze center)
frontal eye field –>PPRF –> CN6 nucleus –> ipsilateral lateral rectus and CN3 nucleas –> contralateral medial rectus

Question 6

what CNs are involved in the vertical saccadic system

what is the vertica gaze center

Answer 6

CN4 nucleus
CN3 nucleus

(riMLF – vertical gaze center)

Question 7

what type(s) of neuronal firing is required for what parts of saccadic movement

Answer 7

burst (excitatory burst neurons) to move eyes toward
object
tonic (tonic neurons) to lock on and fix to the target
pause neurons inhibit burst so no further movements
are made

Question 8

where is the control center for burst cells

horizontal and vertical movement

Answer 8

horizontal - pprf

vertical - riMLF

Question 9

where is the control center for tonic cells

horizontal and vertical movement

Answer 9

horizontal - nucleus prepositus hypoglossi

vertical - interstitial nucleus of cajal

Question 10

where is the control center for pause cells

horizontal and vertical movement

Answer 10

both omnipause cells of raphe nuclei

Question 11

pathology of frontal gaze center

destructive lesion

Answer 11

transient conjugate eye deviation toward the side of the lesion, difficulty looking away from the lesion

Question 12

pathology of frontal gaze center

seizure activity

Answer 12

eyes deviate away from the firing gaze center

Question 13

smooth pursuit pathway

Answer 13

parieto-occipital junction (brodmann 19) –> pontine nuclei –> flocculonodule nuclei –> vestibular nuclei –> CN6/4 nucleus –> CN3 –> horizontal/vertical eye movements

Question 14

optokinetics

Answer 14

holds images of target steady on the retina during head rotations
once visual target reaches limit of the visual field, eyes make a quick move in the opposite direction (optokinetic nystagmus)

Question 15

what does optokinetic eye movements require

Answer 15

intact parietooccipital eye field

Question 16

what can cause the loss of smooth pursuit movements

Answer 16

lesion of parietal lobe

Question 17

doll’s eye maneuver

Answer 17

eyes move in opposite direction of head turn

Question 18

ice water caloric test

Answer 18

COWS

pt must be conscious

Question 19

internuclear ophthalmoplegia

Answer 19

impaired horizontal eye movements
weak adduction of affected eye
abduction nystagmus of contralateral eye
lesion of MLF (pons, midbrain)

Question 20

convergence

Answer 20

image is on fovea

bypasses MLF?

Question 21

accommodation

Answer 21

lens thickens so image is focused on fovea

Question 22

pupillary constriction

Answer 22

better optical performance

Question 23

Argyll-Robertson pupil (neurosyphylis)

Answer 23

absent light reflex but pupil constricts in near reflex testing