Ocular motility

Question 1

Ocular motility - muscles and innervation

Answer 1

1. Superior rectus (CN III)
2. Lateral rectus (CN VI)
3. Inferior oblique (CN III)
4. Inferior rectus (CN III)
5. Medial rectus (CN III)
6. Superior oblique (CN IV)

Question 2

Superior rectus action

Answer 2

Elevate the abducted eye

Question 3

Lateral rectus action

Answer 3

Abduct the eye

Question 4

inferior oblique action

Answer 4

Elevate the adducted eye

Question 5

Medial rectus action

Answer 5

Adduct the eye

Question 6

superior oblique action

Answer 6

Depress the adducted eye

Question 7

trochlea of superior oblique is

Answer 7

a pulley-like structure in the eye. The tendon of the superior oblique muscle passes through it.

Question 8

to test function of each muscle, ask patient to

Answer 8

follow a path from 1ry position

Question 9

left superior oblique and inferior oblique tested with patient …

Answer 9

looking right

Question 10

right superior oblique and inferior oblique tested with patient …

Answer 10

looking left

Question 11

MC affected CN by tuberculosis

Answer 11

CN VI is the most commonly affected VI in immunocompetent people with tuberculosis

Question 12

Abducens nerve (CN VI) damage/palsy - physical finding

Answer 12

Medially directed eye that cannot abduct

• adducted at rest
• cannot be abducted
• diplopia occurs on lateral gaze to the side of the affected eye

Question 13

Trochlear nerve (CN IV) damage/pulsy - eye at rest

Answer 13

Eye moves upward (hypertropia)

Question 14

Trochlear nerve (CN IV) damage/pulsy - increased elevation with

Answer 14

1. adduction (contralateral gaze)

2. head tilting to the affected side

Question 15

Trochlear nerve (CN IV) damage/pulsy - decreased elevation with

Answer 15

1. abduction

2. head tilting to the opposite direction

Question 16

Trochlear nerve (CN IV) damage/pulsy - problems when

Answer 16

going down stairs, reading newspaper (requires looking down and inward)

Question 17

Trochlear nerve (CN IV) damage/pulsy - solution

Answer 17

may present with compensatory head tilt in the opposite direction

Question 18

Oculomotor nerve (CN III) has both ……. components (and area)

Answer 18

1. motor (central of the nerve)

2. parasympathetic (peripheral of the nerve)

Question 19

Motor output of CN III to ocular muscles is affected primarily by ….. due to …..

Answer 19

vascular disease (diabetes mellitus: glucose –> sorbitol) due to decreased diffusion of oxygen and nutrients to the interior fibers from compromises vasculature that resides on outside of nerve

Question 20

Motor output of CN III to ocular muscles - signs of damage

Answer 20

1. ptosis

2. down and out gaze

Question 21

Parasympathetic output of CN III - causes of damage (mechanism)(not examples)

Answer 21

fibers on the periphery are 1st affected by compression

Question 22

Parasympathetic output of CN III - examples of compression

Answer 22

1. uncal herniation

2. Posterior communicating artery aneurysm

Question 23

The uncus is (area)

Answer 23

an anterior extremity of the Parahippocampal gyrus

Question 24

Parasympathetic output of CN III - signs of damage

Answer 24

1. diminished or absent papillary light reflex
2. Blown pupil (mydriasis)
3. often with down and out gaze

Question 25

CN VI palsy - diplopia occurs

Answer 25

On lateral gaze to the side of the affected eye

Question 26

CN IV palsy - diplopia is most pronounced when the patients

Answer 26

Look downward with the affected eye adducted

Question 27

CN VI palsy - diplopia occurs

Answer 27

On lateral gaze to the side of the affected eye

Question 28

Central vs peripheral area of CN III

Answer 28

central: Motor peripheral: Parasympathetics