Visual System - Eye Movements

Question 1

List two types of eye movements.

Answer 1

voluntary

involuntary

Question 2

Why is eye movement necessary?

Answer 2

acquiring and tracking visual stimuli

Question 3

Eye movements are facilitated by what muscles?

Answer 3

6 extraocular muscles

Question 4

Extraocular muscles are innervated by?

Answer 4

CN III, IV, VI

Question 5

What is duction?

Answer 5

eye movement in one eye

Question 6

What is version?

Answer 6

simultaneous movement of both eyes in the same direction

Question 7

What is vergence?

Answer 7

simultaneous movement of both eyes in the opposite direction

Question 8

What is convergence?

Answer 8

simultaneous adduction movement in both eyes when viewing a near object

Question 9

What is saccade?

Answer 9

short fast burst of movement

up to 900 degrees /sec

Question 10

List types of saccade.

Answer 10

reflexive saccade
scanning saccade
predictive saccade to track objects
memory-guided saccade

Question 11

What is smooth pursuit?

Answer 11

sustained slow movement

up to 60 degrees/sec

Question 12

What is smooth pursuit driven by?

Answer 12

motion of a moving target across the retina

Question 13

The extraocular muscles attach (?) to (?)

Answer 13

eyeball

orbit

Question 14

What are the four straight extraocular muscles?

Answer 14

superior rectus
inferior rectus
lateral rectus
medial rectus

Question 15

What is the muscle action of the superior rectus? Where is it attached?

Answer 15

moves the eye up

attached at 12 o clock

Question 16

What is the muscle action of the inferior rectus? Where is it attached?

Answer 16

moves the eye down

attached at 6 o clock

Question 17

What is the muscle action of the lateral rectus? Where is it attached?

Answer 17

moves the eye towards the outside of the head

attaches on the temporal side of the eye

Question 18

What is the muscle action of the medial rectus? Where is it attached?

Answer 18

moves the eye toward the middle of the head/toward the nose

attached on nasal side of the eye

Question 19

Apart from the ‘x rectus’ extraocular muscles, what two other muscles are there?

Answer 19

superior oblique

inferior oblique

Question 20

Where is the superior oblique attached?

Answer 20

high on the temporal side

Question 21

The superior oblique passes under what muscle?

Answer 21

superior rectus

Question 22

What is the muscle action of the superior oblique?

Answer 22

moves the eye down and out

Question 23

The superior oblique passes through what important structure?

Answer 23

trochlea

Question 24

Where is the inferior oblique attached?

Answer 24

low on the nasal side of the eye

Question 25

The inferior oblique passes over what muscle?

Answer 25

inferior rectus

Question 26

What is the muscle action of the inferior oblique?

Answer 26

moves the eye up and out

Question 27

Superior rectus is innervated by?

Answer 27

superior branch of the oculomotor nerve (CN III)

Question 28

LPS is innervated by?

Answer 28

superior branch of oculomotor (CN III)

Question 29

Inferior rectus is innervated by?

Answer 29

inferior branch of the oculomotor nerve (CN III)

Question 30

Medial rectus is innervated by?

Answer 30

inferior branch of the oculomotor nerve (CN III)

Question 31

Inferior oblique is innervated by?

Answer 31

inferior branch of oculomotor nerve (CN III)

Question 32

Superior oblique is innervated by?

Answer 32

trochlear nerve (CN IV)

Question 33

Lateral rectus is innervated by?

Answer 33

abducens (CN VI)

Question 34

3rd nerve palsy causes what eye issues?

Answer 34

``` affected eye moves down and out droopy eyelid (loss of LPS) ```

Question 35

6th nerve palsy causes what eye issues?

Answer 35

affected eye unable to abduct and deviated inwards | double vision worsen on gazing to the side of the affected eye

Question 36

What is nystagmus?

Answer 36

oscillatory eye movement

Question 37

What is optokinetic nystagmus?

Answer 37

smooth pursuit + fast phase reset saccade

Question 38

Optokinetic nystagmus reflex is useful for?

Answer 38

testing visual acuity in pre verbal children by observing presence of nystagmus movement in response to moving grating patterns of various spatial frequencies