Week 8: Extraocular Movements

Question 1

LR6

Answer 1

Lateral Rectus innervated by CN VI (Abducens)

Question 2

SO4

Answer 2

Superior Oblique innervated by CN IV (Trochlear)

Question 3

ATR3

Answer 3

All the rest innervated by CN III (oculomotor)

Question 4

Anatomical function of Lateral Rectus

Answer 4

abduction (the strong abductor)

Question 5

Anatomical function of Medial Rectus

Answer 5

adduction

Question 6

Anatomical function of Superior Rectus

Answer 6

elevation and adduction

Question 7

Anatomical function of Inferior Rectus

Answer 7

depression and adduction

Question 8

Anatomical function of Superior Oblique

Answer 8

depression and abduction

Question 9

Anatomical function of Inferior Oblique

Answer 9

elevation and abduction

Question 10

Muscles that help adduct the eye

Answer 10

MR, SR, and IR

Question 11

Muscles that help abduct the eye

Answer 11

LR, SO, and IO

Question 12

Muscles the help elevate the eye

Answer 12

SR and IO

Question 13

Muscles the help depress the eye

Answer 13

IR and SO

Question 14

2 axes of rotation for eye

Answer 14

• horizontal: elevate and depress

* vertical: abduction and adduction

Question 15

How to test the Lateral Rectus

Answer 15

look lateral

Question 16

How to test the Medial Rectus

Answer 16

look medial

Question 17

How to test the Superior Rectus

Answer 17

look lateral, then up

lateral opposes the adduction function of the SR

Question 18

How to test the Inferior Rectus

Answer 18

look lateral, then down

lateral opposes the adduction function of the IR

Question 19

How to test the Inferior Oblique

Answer 19

look medial, then up

medial opposes the abduction function of the IO

Question 20

How to test the Superior Oblique

Answer 20

look medial, then down

medial opposes the abduction function of the SO

Question 21

By having patient follow your finger as you trace an “H” in front of each eye…

Answer 21

you can test the 3 cranial nerves involved in extraocular movement (III, IV, and VI)

Question 22

Problems with Oculomotor nerve (III) cause

Answer 22

affected eye to drift down and out

Question 23

Loss of oculomotor nerve cause muscles supplied by trochlear and abducens to take over…

Answer 23

•trochlear (SO) - depress and abducts eye
•abducens (LR) - abducts eye
*Patient will also have ptosis and mydriasis

Question 24

ptosis is

Answer 24

drooping of eyelid

Question 25

mydriasis is

Answer 25

pupil dilation

Question 26

Problems with Trochlear nerve (IV) cause

Answer 26

affected eye to drift upward

Question 27

Loss of trochlear nerve cause muscles supplied by oculomotor and abducens to take over…

Answer 27

• oculomotor
• abducens (LR) - abducts eye
• some loss of depression will occur, ab- and adduction will be normal

Question 28

Problems with Abducens nerve (VI) cause

Answer 28

affected eye to drift medially

Question 29

Loss of abducens nerve cause muscles supplied by oculomotor and trochlear to take over…

Answer 29

the strong adductor of the eye will take over (MR)