Extraocular Muscles + Eye Movements

Question 1

What are the axes of the eyes

Answer 1

Visual axis
Orbital axis

Question 2

Insertion of extra ocular muscles

Answer 2

All insert into sclera

Question 3

Why do we have two eyes?

Answer 3

• Stereoscopic vision (depth perception)
• Wider field of vision

Question 4

What is stereoscopic vision?

Answer 4

Depth perception (3D)

Question 5

What is conjugate gaze?

Answer 5

The movement of both eyes in the same direction synonymously

Question 6

What is binocular vision?

Answer 6

The ability of both eyes to face the same direction + perceive a single 3D image **

Question 7

What can you do to test if dipopia is due to misalignment of visual axes?

Answer 7

Covering over either eye > diplopia disappears

Question 8

What are the extra ocular muscles of the eye?

Answer 8

Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus

Superior oblique
Inferior oblique

Question 9

What is primary resting gaze?

Answer 9

Position of eyes when looking straight ahead

Question 10

What axis do the extra ocular muscles run in line with?

Answer 10

Orbital axis

Question 11

Innervation of the extra ocular muscles

Answer 11

LR6 SO4 R3
- lateral rectus: abducens CN VI
- superior oblique: trochlear CN IV
- rest: oculomotor CN III

Question 12

Origin of the extra ocular muscles

Answer 12

• At the apex of the orbital cavity
• Rectus muscles come from the common tendinous ring

Question 13

Describe the role of the extra ocular muscles at primary resting gaze

Answer 13

Equal and opposite pull of all extra ocular muscles

Question 14

Describe the action of the extra ocular muscles when changing position of gaze

Answer 14

• Exert greater pull through action of certain extraocular muscles
• Antagonists relax

Question 15

Action of superior rectus from primary resting gaze

Answer 15

Elevation
Intorsion
ADuction

Question 16

Action of inferior rectus from primary resting gaze

Answer 16

Depression
Extorsion
ADuction

Question 17

Action of medial rectus

Answer 17

ADduction

Question 18

Action of lateral rectus

Answer 18

ABduction

Question 19

Action of superior oblique from primary resting gaze

Answer 19

Intorsion
Depression
ABduction

Question 20

Action of inferior oblique from primary resting gaze

Answer 20

Extorsion
Elevation
ABduction

Question 21

Action of superior rectus when eye is positioned laterally

Answer 21

Elevation dominates

Question 22

Action of inferior rectus when eye is position laterally

Answer 22

Depression dominates

Question 23

Action of superior oblique when eye is positioned medially

Answer 23

Depression dominates

Question 24

Action of inferior oblique when eye is positioned medially

Answer 24

Elevation dominates

Question 25

What extra ocular muscles are stronger elevators ad depressors of the eyeball when the eye is in the ABducted (lateral) position?

Answer 25

Superior rectus E Inferior rectus D

Question 26

What extra ocular muscles are stronger elevators ad depressors of the eyeball when the eye is in the ADducted (medial) position?

Answer 26

Superior oblique D Inferior oblique E

Question 27

Define esotropic

Answer 27

Form of strabismus when one or both of the eyes turn inwards (ADducted)

Question 28

Define hypertopia

Answer 28

A condition where one of the eyes is elevated

Question 29

What is strabismus?

Answer 29

Ocular misalignment (Squint)

Question 30

Clinical testing of eye muscles

Answer 30

H movement to isolate + test each muscle

Question 31

What is the likely cause of a oculomotor nerve issue if the pupil is spared?

Answer 31

Micro vascular ischameia (Diabetes, hypertensive)

Question 32

How to remember the actions of the oblique extra ocular muscles?

Answer 32

o**B**lique - a**B**duction **O**blique - **O**pposite (superior depresses, inferior elevate) Superior oblique - depression + ABduction Inferior oblique - elevation + ABduction

Question 33

What is the position of the eye in a trochlear nerve lesion?

Answer 33

**Up + in** Superior oblique innervation lost (depression + ABduction)

Question 34

What is the position of the eye in oculomotor nerve lesion?

Answer 34

**Down + out** Lateral rectus + superior oblique still work (ABduction + depression)

Question 35

What could causes micro vascular ischaemia?

Answer 35

Diabetes Hypertension