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HNN > Extraocular Muscles + Eye Movements > Flashcards

Extraocular Muscles + Eye Movements Flashcards

1
Q

What are the axes of the eyes

A

Visual axis
Orbital axis

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2
Q

Insertion of extra ocular muscles

A

All insert into sclera

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3
Q

Why do we have two eyes?

A
  • Stereoscopic vision (depth perception)
  • Wider field of vision
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4
Q

What is stereoscopic vision?

A

Depth perception (3D)

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5
Q

What is conjugate gaze?

A

The movement of both eyes in the same direction synonymously

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6
Q

What is binocular vision?

A

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

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7
Q

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

A

Covering over either eye > diplopia disappears

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8
Q

What are the extra ocular muscles of the eye?

A

Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus

Superior oblique
Inferior oblique

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9
Q

What is primary resting gaze?

A

Position of eyes when looking straight ahead

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10
Q

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

A

Orbital axis

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11
Q

Innervation of the extra ocular muscles

A

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

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12
Q

Origin of the extra ocular muscles

A
  • At the apex of the orbital cavity
  • Rectus muscles come from the common tendinous ring
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13
Q

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

A

Equal and opposite pull of all extra ocular muscles

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14
Q

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

A
  • Exert greater pull through action of certain extraocular muscles
  • Antagonists relax
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15
Q

Action of superior rectus from primary resting gaze

A

Elevation
Intorsion
ADuction

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16
Q

Action of inferior rectus from primary resting gaze

A

Depression
Extorsion
ADuction

17
Q

Action of medial rectus

A

ADduction

18
Q

Action of lateral rectus

A

ABduction

19
Q

Action of superior oblique from primary resting gaze

A

Intorsion
Depression
ABduction

20
Q

Action of inferior oblique from primary resting gaze

A

Extorsion
Elevation
ABduction

21
Q

Action of superior rectus when eye is positioned laterally

A

Elevation dominates

22
Q

Action of inferior rectus when eye is position laterally

A

Depression dominates

23
Q

Action of superior oblique when eye is positioned medially

A

Depression dominates

24
Q

Action of inferior oblique when eye is positioned medially

A

Elevation dominates

25
Q

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

A

Superior rectus E
Inferior rectus D

26
Q

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

A

Superior oblique D
Inferior oblique E

27
Q

Define esotropic

A

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

28
Q

Define hypertopia

A

A condition where one of the eyes is elevated

29
Q

What is strabismus?

A

Ocular misalignment
(Squint)

30
Q

Clinical testing of eye muscles

A

H movement to isolate + test each muscle

31
Q

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

A

Micro vascular ischameia
(Diabetes, hypertensive)

32
Q

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

A

oBlique - aBduction
Oblique - Opposite (superior depresses, inferior elevate)

Superior oblique - depression + ABduction
Inferior oblique - elevation + ABduction

33
Q

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

A

Up + in

Superior oblique innervation lost (depression + ABduction)

34
Q

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

A

Down + out

Lateral rectus + superior oblique still work (ABduction + depression)

35
Q

What could causes micro vascular ischaemia?

A

Diabetes
Hypertension

HNN (24 decks)

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