Cranial Nerves - Oculomotor

Question 1

For the visual system to work efficiently, both eyes

Answer 1

must focus and remain focused on an object so the information can reach cortex in a form that can result in vision.

Question 2

While we can detect objects over a large range extending into the periphery, we “see” objects only when

Answer 2

they are focused on the fovea

Question 3

The oculomotor system works primarily

Answer 3

control the movement of our eyes

Question 4

The oculomotor system works primarily to control the movement of our eyes, and is designed to (2)

Answer 4

1. bring targets onto the fovea

2. keep them there

Question 5

Historically five movement systems have been identified that put the fovea on a target (both eyes in a conjugate manner; foveation) and keep it there. (5)

Answer 5

1. Vestibulo-ocular
2. Optokinetic
3. Saccade
4. Smooth pursuit
5. Vergence

Question 6

Systems that stabilize the eye when the head moves (2)

Answer 6

1. Vestibulo-ocular

2. Optokinetic

Question 7

How does Vestibulo-ocular stabilize the eye when the head moves?

Answer 7

Vestibular input holds images stable on retina during head and body movement; gaze stabilization

Question 8

How does Optokinetic stabilize the eye when the head moves?

Answer 8

visual input holds image stale on retina during sustained or slow head rotation

Question 9

Systems that keep the fovea on a visual target (3)

Answer 9

1. Saccade
2. Smooth pursuit
3. Vergence

Question 10

How does Saccade keep the fovea on a visual target?

Answer 10

brings new object of interest onto fovea

Question 11

How does Smooth Pursuit keep the fovea on a visual target?

Answer 11

holds image of a moving target on the fovea

Question 12

How does Vergence keep the fovea on a visual target?

Answer 12

adjusts the eyes for viewing different distances in depth

Question 13

In an oculomotor system that is functioning normally, the two eyes are “locked together which allows

Answer 13

for both eyes to be focused on an object

Question 14

What is retinal disparity?

Answer 14

If the oculomotor system becomes “unlocked” and the eyes focus on different targets.

Question 15

What happens to vision if retinal disparity occurs?

Answer 15

diplopia or double vision occurs.

Question 16

Vestibulo-ocular, Optokinetic, Saccade, and Smooth pursuit allow for

a. conjugate movements
b. disconjugate movements

Answer 16

a. conjugate movements of the eyes for foveation

Question 17

Vergence allows for

a. conjugate movements
b. disconjugate movements

Answer 17

b. disconjugate movements, convergence and divergence

Question 18

The ___ system is used to quickly reposition the eyes (fovea) to focus on an image that has suddently been moved from the fovea.

Answer 18

Saccade System

Question 19

T/F: Saccades can be horizontal or vertical.

Answer 19

True

Question 20

The rapid eye movement required to bring the image back into focus is a

Answer 20

saccade

Question 21

Reading a neuro handout is done by a series of

Answer 21

conjugate saccadic eye movements

Question 22

Saccadic eye movements can be elicited by

Answer 22

visual input, as well as other stimuli, such as auditory stimuli, memories of locations, or verbal commands

Question 23

With saccadic eye movements, both eyes move in a conjugate manner, in terms of

Answer 23

velocity, amplitude, and direction, for reestablishment of the image on the fovea.

Question 24

The conjuage saccade system is directed through a

Answer 24

horizontal gaze center

Question 25

the horizontal gaze center is located in the

Answer 25

pontine reticular formation (paramedian pontine reticular formation; PPRF) adjacent to the abducens nucleus.

Question 26

The saccade system UMN control is a complicated system of interneurons, that involves a part of the

Answer 26

middle frontral gyrus termed the Frontal Eye Fields (FEF; area 8) and the Superior Colliculus.

Question 27

The middle frontal gyrus termed the Frontal Eye Fields (FEF; area 8) and the Superior Colliculus is represented on both hemispheres and contains specific regions termed

Answer 27

horizontal gaze center, vertical gaze center, and vergence center. (these are separate and distinct regions within area 8.