4.19 Vestibular 3 Flashcards Preview

7303 Neuroanatomy > 4.19 Vestibular 3 > Flashcards

Flashcards in 4.19 Vestibular 3 Deck (28):
1

What are the 2 eye reflexes we talked about for gaze stabilization?

- vestibulo-ocular reflex (VOR)
- optokinetic reflex

2

What is gaze stabilization

visual fixation: keeping gaze steady during head movements

3

What does the VOR do?

- stabilizes visual field during fast head movements
- moves the eyes in the opposite direction to the head

4

VOR: voluntary or automatic?

automatic

5

frontal control and VOR

frontal control required to suppress the VOR and move eyes with the head

6

What happens to the eyes when you move the head quickly

they lag behind

7

What type of reflex is the VOR considered?

brainstem reflex

8

VOR is needed to be able to do this

look L & R back and forth (as well as up/down)

9

Why does nystagmus occur? (VOR)

- excessive VOR stimulation
- pathological damage

VOR can't keep up with head rotation

10

VOR normally does this for rotation

compensates for rotation

11

How can the VOR be triggered normally?

- excessive rotation
- quickly moving objects

12

What is pathologic nystagmus?

nystagmus with NO excessive rotation

13

Where is the damage with pathologic nystagmus?

in the semicircular canals or the receptors for the canals

(could also be in the vestibulocerebellum or due to a problem with the otoliths)

14

Both the optokinetic and the VOR go through this nucleus

medial vestibular nucleus

15

function of optokinetic reflex

- stabilizes images during slow head movements
- helps focus on larger objects int he visual field

16

Where does the optokinetic cut through (as well as the medial vestibular nucleus)

pretectal area

17

Where does the optokinetic reflex start?

receptors in the retina

18

Where does the VOR start?

inner ear

19

3 major eye movement types

- saccades
- smooth pursuits
- eye vergence

20

What are saccades?

fast eye movements from one object to another

21

What do saccades allow for?

- allows you to see new object details
- how you follow something in visual field without really realizing it

22

saccades go through this area

superior colliculus

23

What is the superior colliculus?

unconscious visual center

24

smooth pursuits

eye tracking to follow a moving target

25

smooth pursuits: voluntary or involuntary?

requires conscious effort

26

eye vergence

purposeful alignment of the eyes on a near target

27

What is eye vergence similar to? (reflex)

accommodation

28

How is eye vergence and accommodation reflex different?

eye vergence is purposeful