L29 Eye Movements

Question 1

What are the 2 types of eye movements

Answer 1

conjugate eye movements (eyes moving together)

non-conjugate eye movements (eyes move in different directions)

Question 2

what movements fall under conjugate eye movements

Answer 2

saccadic movement/gaze
vestibulo-occular reflex
optokinetic reflex

Question 3

what is saccadic movement/gaze

Answer 3

voluntary movements

my eyes will “jump” from one point to the next point = scanning a picture

Question 4

what is the vestibule-occular reflex

Answer 4

uses vestibular system in the event that the head is spun/turned rapidly
keeps my eyes in position of former point of fixation

Question 5

what is the optokinetic reflex?

Answer 5

utilized in a situation such as watching landscape pass rapidly while I’m in a train
my eyes move rapidly to keep the object of focus in the center of the visual field for as long as possible

Question 6

what movements fall under non-conjugate movements?

Answer 6

vergence

dysconjugate gaze

Question 7

what is vergence?

Answer 7

convergence - eyes move towards each other

divergence - eyes move away from each other

Question 8

what is dysconjugate gaze?

Answer 8

pathological movement pattern -

eyes move erratically and totally independent of each other!

Question 9

what is the mneumonic for extraocular muscles and the nerves that innervate them

Answer 9

LR6(SO4)3

Question 10

where is the nerve nuclei for CN III and IV?

Answer 10

midbrain - tegmentum
CN III nuclei at level of SC
CN IV nuclei at level of IC

Question 11

what is the MLF?

Answer 11

for ascending neurons from abducens nucleus to occulomotor nucleus

Question 12

what is the role of superior colliculus? what eye movement can it participate in?

Answer 12

receives info from the retinal ganglion cells and can participate in saccadic eye movements

Question 13

what is MLF essential for

Answer 13

necessary for conjugate eye movement

Question 14

where is the nerve nuclei for CN VI located?

Answer 14

lower pons

Question 15

what is the role of PPRF

Answer 15

initial activate CN IV to begin conjugate eye movements (including saccadic eye movements)

Question 16

where is the vestibular nuclei located

Answer 16

from pons to the MEDULLA

Question 17

what does the vestibular nuclei control

Answer 17

the vestibulo-ocular reflex

Question 18

what is the role of the cerebellum (particularly the vestibule-cerebellum) ?

Answer 18

participates in the optokinetic reflex

Question 19

what is the role of the frontal eye field ?

Answer 19

role in planning and initiation of eye movements (seen in saccadic eye movements)

Question 20

what brodmanns area corresponds to the frontal eye field?

Answer 20

Area 8

Question 21

what is the location and role of the parieto-occipital eye field?

Answer 21

at junctions of parietal and occipital lobe

output is involved in depth and motion

Question 22

what is the purpose of saccadic eye movements

Answer 22

extremely fast movements used to keep the target in focus on the fovea (used for scanning)

Question 23

how will a trochlear nerve palsy (CN IV) present?

Answer 23

eye = up and in

unopposed IO

Question 24

how will a occulomotor nerve palsy (CN III) present?

Answer 24

eye = down and out

unopposed LR and SO

Question 25

how will a abducens nerve palsy (CN VI) present?

Answer 25

eye = medial deviation

unopposed MR

Question 26

describe diplopia

Answer 26

causes by the fact that an image is landing on different points of the visual field for each eye because one eye is unable to focus the image properly on the fovea

when V1 gets the info - it registers it as actually existing in 2 places = double vision

Question 27

what is an internuclear ophthalmoplegia

Answer 27

lesion of MLF
abducens n. cannot transmit info to oculomotor n.
so same side MR cannot work

Question 28

what is a PPRF lesion?

Answer 28

= inability to trigger same abducens n. = inability to initiate and send info up the MLF