Cranial Nerves - Oculomotor Flashcards Preview

DPT704: Neuro Hank > Cranial Nerves - Oculomotor > Flashcards

Flashcards in Cranial Nerves - Oculomotor Deck (27):
1

For the visual system to work efficiently, both eyes

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

2

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

they are focused on the fovea

3

The oculomotor system works primarily

control the movement of our eyes

4

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

1. bring targets onto the fovea
2. keep them there

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)

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

6

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

1. Vestibulo-ocular
2. Optokinetic

7

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

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

8

How does Optokinetic stabilize the eye when the head moves?

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

9

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

1. Saccade
2. Smooth pursuit
3. Vergence

10

How does Saccade keep the fovea on a visual target?

brings new object of interest onto fovea

11

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

holds image of a moving target on the fovea

12

How does Vergence keep the fovea on a visual target?

adjusts the eyes for viewing different distances in depth

13

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

for both eyes to be focused on an object

14

What is retinal disparity?

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

15

What happens to vision if retinal disparity occurs?

diplopia or double vision occurs.

16

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

a. conjugate movements
b. disconjugate movements

a. conjugate movements of the eyes for foveation

17

Vergence allows for

a. conjugate movements
b. disconjugate movements

b. disconjugate movements, convergence and divergence

18

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

Saccade System

19

T/F: Saccades can be horizontal or vertical.

True

20

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

saccade

21

Reading a neuro handout is done by a series of

conjugate saccadic eye movements

22

Saccadic eye movements can be elicited by

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

23

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

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

24

The conjuage saccade system is directed through a

horizontal gaze center

25

the horizontal gaze center is located in the

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

26

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

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

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

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