Visual System Eye movements

Question 1

How is voluntary or involuntary movement of eyes done?

Answer 1

Facilitated by the six extraocular muscles innervated by the three cranial nerves (III, IV and VI)

Question 2

Why is eye movement important?

Answer 2

helps to acquire and track visual stimuli.

Question 3

What is duction?

Answer 3

Eye Movement in One Eye

Question 4

What is version?

Answer 4

Simultaneous movement of both eyes in the same direction

Question 5

What is vergence?

Answer 5

Simultaneous movement of both eyes in the opposite direction

Question 6

What is convergence?

Answer 6

Simultaneous adduction (inward) movement in both eyes when viewing a near object

Question 7

What is gazing to the left?

Answer 7

Levoversion

Question 8

What is gazing to the right?

Answer 8

Dextroversion

Question 9

What is saccade eye movement?

Answer 9

short fast burst, up to 900°/sec

Question 10

What are different types of saccade?

Answer 10

•Reflexive saccade to external stimuli
•Scanning saccade
•Predictive saccade to track objects
•Memory-guided saccade
-Can be voluntary or involuntary

Question 11

What is smooth pursuit?

Answer 11

sustain slow movement

Question 12

What are types of smooth pursuit?

Answer 12

•Slow movement – up to 60°/s
•Driven by motion of a moving target across the retina.
-Involuntary for moving target

Question 13

What are the 4 straight extra ocular muscles?

Answer 13

1. Superior rectus
   2 .Inferior rectus
2. Lateral rectus
3. Medial rectus

Question 14

Where do 5 out of the 6 muscles come out from?

Answer 14

Cone from back of orbit

Question 15

How does the inferior oblique come in?

Answer 15

nasally

Question 16

Where is the superior rectus attached to the eye?

Answer 16

at 12 o’clock

Question 17

What does the superior rectus do?

Answer 17

Moves eye up

Question 18

Where is the inferior rectus attached to the eye?

Answer 18

at 6 o’clock

Question 19

What does the inferior rectus do?

Answer 19

Moves eye down

Question 20

What do vertical rectus muscles to?

Answer 20

attach anterior to the globe equator,

and pull backwards and nasally.

Question 21

What happens when the eye is in an adducted position?

Answer 21

the anterior-posterior axis of the eye is not aligned with the vertical rectus muscle action

Question 22

What happens when the eye is in an abducted position?

Answer 22

the anterior-posterior axis of the eye is aligned with the insertion of the vertical rectus muscles

Question 23

What do the superior and inferior rectus to when the eye is in an abducted position?

Answer 23

1. Superior Rectus muscle: elevates the eye maximally

2. Inferior Rectus muscle: depresses the eye maximally

Question 24

What do vertical rectus muscles do when the eye is in an adducted position?

Answer 24

Vertical rectus muscles produce torsion motion instead

Question 25

Where does the lateral rectus attach?

Answer 25

temporal side of the eye

Question 26

What does the lateral rectus do?

Answer 26

Moves the eye toward the outside of the head (toward the temple)

Question 27

Where is the medial rectus attached?

Answer 27

nasal side of the eye

Question 28

What does the medial rectus do?

Answer 28

Moves the eye toward the middle of the head (toward the nose)

Question 29

Where is the superior oblique attached?

Answer 29

- Attached high on the temporal side of the eye | - Passes under the Superior Rectus

Question 30

What does the superior oblique do?

Answer 30

Moves the eye in a diagonal pattern down and out

Question 31

What does the superior oblique travel through?

Answer 31

trochlea

Question 32

Where is the inferior oblique attached?

Answer 32

- Attached low on the nasal side of the eye. | - Passes over the Inferior Rectus

Question 33

What does the inferior oblique do?

Answer 33

Moves the eye in a diagonal pattern - up and out

Question 34

What does the superior branch of the oculomotor nerve (III) innervate?

Answer 34

1. Superior Rectus – elevates eye | 2. levator palpebrae superioris - raises eyelid (not shown)

Question 35

What does the inferior branch of the oculomotor nerve (III) innervate?

Answer 35

1. Inferior Rectus – depresses eye 2. Medial Rectus – adducts eye 3. Inferior Oblique – elevates eye 4. Parasympathetic Nerve – constricts pupil

Question 36

What does the trochlear (IV) nerve innervate?

Answer 36

Superior Oblique – depresses eye

Question 37

What does the abducens (VI) nerve innervate?

Answer 37

Lateral Rectus – abducts eye

Question 38

How do you test extra ocular muscles?

Answer 38

Isolate muscle to be tested by maximizing its action and minimizing the action of other muscles

Question 39

In what position is the lateral rectus action best tested?

Answer 39

abduction

Question 40

In what position is the medial rectus action best tested?

Answer 40

adduction

Question 41

In what position is the superior rectus action best tested?

Answer 41

elevated and abducted

Question 42

In what position is the inferior rectus action best tested?

Answer 42

depressed and abducted

Question 43

In what position is the inferior oblique action best tested?

Answer 43

elevated and adducted

Question 44

In what position is the superior oblique action best tested?

Answer 44

depressed and adducted

Question 45

What is supraversion and supraduction?

Answer 45

Elevation: Supraduction – one eye Supraversion – both eyes

Question 46

What is infraversion and infraduction?

Answer 46

Depression (down): Infraduction – one eye Infraversion – both eyes

Question 47

What is abduction?

Answer 47

refers to duction movement of one eye, | moving away from the nose

Question 48

What is adduction?

Answer 48

refers to duction movement of one eye, | moving towards the nose

Question 49

What is dextroversion?

Answer 49

involves simultaneous right eye abduction, | and left eye adduction

Question 50

What is levoversion?

Answer 50

involves simultaneous left eye abduction, | and right eye adduction

Question 51

What is third nerve palsy signs?

Answer 51

1. Affected eye goes down and out 2. Droopy eyelid (loss of elevator palpebrae superioris as innervated by superior branch of occuolomotor nerve) 3. Unopposed superior oblique innervated by fourth nerve (down) 4. Unopposed lateral rectus action innervated by sixth nerve (out)

Question 52

What happens in complete third nerve palsy?

Answer 52

-only muscles not innervated by the third cranial nerve in the affected eye are working -lateral rectus muscle, responsible for abduction, and superior oblique muscle, responsible for depression -causes over-action of the two unopposed muscles, and the affected eye adopts a down and out position

Question 53

What is sixth nerve palsy?

Answer 53

1. Affected eye unable to abduct and deviates inwards | 2. Double vision worsen on gazing to the side of the affected eye

Question 54

What is the deficit in sixth nerve palsy?

Answer 54

deficit in abduction in the affected eye, affected eye deviates inward

Question 55

What is nystagmus?

Answer 55

Oscillatory eye movement

Question 56

What is Optokinetic Nystagmus?

Answer 56

Smooth Pursuit + Fast Phase Reset Saccade

Question 57

When is Optokinetic Nystagmus Reflex useful?

Answer 57

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

Question 58

What does Presence of Optokinetic Nystagmus in response to moving grating show?

Answer 58

that the subject has sufficient visual acuity to perceive the grating pattern

Question 59

What is torsion?

Answer 59

rotation of eye around the anterior-posterior axis of the eye

Question 60

Is it possible to have 4th nerve palsy?

Answer 60

Yes