Eye Movements of the Visual System

Question 1

How many muscles innervate the eye?

Answer 1

6

Question 2

What nerves innervate the eye muscles?

Answer 2

CN III (oculomotor)
CN IV (trochlear)
CN VI (abducens)

Question 3

Define duction

Answer 3

Eye movement in one eye

Question 4

Define version

Answer 4

Simultaneous movement of both eyes in the same direction

Question 5

Define vergence

Answer 5

Simultaneous movement of both eyes in the opposite direction to version

Question 6

Define convergence

Answer 6

Simultaneous adduction of both eyes when viewing a near object

Question 7

Define saccades

Answer 7

Short, fast bursts of movement

Question 8

What are the different types of saccades and what do they mean?

Answer 8

Reflexive saccade (to external stimuli)
Scanning saccade
Predictive saccade (to track objects)
Memory guided saccade

Question 9

Define smooth persuit

Answer 9

Sustained slow movements of the eye

Question 10

Where does the superior oblique move the eye?

Answer 10

Down and out

Question 11

Where does the inferior oblique move the eye?

Answer 11

Up and out

Question 12

What nerves innervate which of the 6 eye muscles

Answer 12

Oculomotor innervates all of them (including levator palpabrae superioris) apart from
LR6SO4
Lateral rectus is innervated by CN VI (abducens)
Superior oblique is innervated by CN IV (trochelar)

Question 13

What muscle does abduction test?

Answer 13

Lateral rectus

Question 14

What muscle does adduction test?

Answer 14

Medial rectus

Question 15

What muscle does elevation and abduction test?

Answer 15

Superior rectus

Question 16

What muscle does elevation and adduction test?

Answer 16

Inferior oblique

Question 17

What muscle does depression and abduction test?

Answer 17

Inferior rectus

Question 18

What muscle does depression and adduction test?

Answer 18

Superior oblique

Question 19

What do the suffixes duction and version indicate in terms of movements of the ye

Answer 19

duction= one eye
version= both eyes

Question 20

What are the prefixes in terms of eye movement for elevation, depression, right and left?

Answer 20

Elevation= supra
Depression= infra
Right= dextro
Left= levo

Question 21

Define torsion as an eye movement

Answer 21

Rotation of eye around the anterior posterior axis of the eye

Question 22

How does the affected eye appear in third nerve palsy- explain why

Answer 22

The eye goes down and out (the lateral rectus and superior oblique are unaffected as they aren’t innervated by CN III) and the eyelid is droopy (the levator palpabrae superioris isnt working)

Question 23

How does the affected eye appear in sixth nerve palsy- explain why

Answer 23

Affected eye cannot abduct because the lateral rectus isnt working so it deviated inwards

Question 24

When does double vision occur in sixth nerve palsy?

Answer 24

When gazing to the side of the affected eye

Question 25

When is the optokinetic nystagmus reflex used and what does it indicate?

Answer 25

It is used to check that there is normal visual acuity in children who can’t speak yet