Muscles of the eye

Question 1

How many extra-ocular muscles move the eyeball?

Answer 1

Six

Question 2

What are the six extra-ocular muscles moving the eyeball?

Answer 2

Superior rectus
Inferior rectus
Medial rectus
Lateral rectus

Superior oblique
Inferior oblique

Question 3

What do the rectus muscles originate from?

Answer 3

Fibrous ring surrounding optic canal

Question 4

What do the rectus muscles insert into?

Answer 4

Sclera of eye relatively anteriorly

Question 5

What do the oblique muscles originate from?

Answer 5

Anatomically - apex of orbit

Functionally - trochlea on medial wall of orbit, anteriorly

Question 6

What do the oblique muscles insert into?

Answer 6

Sclera of eye relatively posteriorly

Question 7

What innervates the superior rectus muscle?

Answer 7

CN3 oculomotor nerve

Question 8

What innervates the inferior rectus muscle?

Answer 8

CN3 oculomotor nerve

Question 9

What innervates the medial rectus muscle?

Answer 9

CN3 oculomotor nerve

Question 10

What innervates the lateral rectus muscle?

Answer 10

CN6 abducens nerve

Question 11

What innervates the superior oblique muscle?

Answer 11

CN4 trochlear nerve

Question 12

What innervates the inferior oblique muscle?

Answer 12

CN3 oculomotor nerve

Question 13

What are the actions of the superior rectus muscle?

Answer 13

Moves the eye superiorly

Moves the eye medially

Question 14

What are the actions of the inferior rectus muscle?

Answer 14

Moves the eye inferiorly

Moves the eye medially

Question 15

What are the actions of the medial rectus muscle?

Answer 15

Moves the eye medially

Question 16

What are the actions of the lateral rectus muscle?

Answer 16

Moves the eye laterally

Question 17

What are the actions of the superior oblique muscle?

Answer 17

Moves the eye inferiorly

Moves the eye laterally

Intorts the eye

Question 18

What are the actions of the inferior oblique muscle?

Answer 18

Moves the eye superiorly

Moves the eye laterally

Extorts the eye

Question 19

Which muscles move the eye directly superiorly? How?

Answer 19

Superior rectus

Inferior oblique

their other actions cancel each other out

Question 20

Which muscles move the eye directly inferiorly? How?

Answer 20

Inferior rectus

Superior oblique

their other actions cancel each other out

Question 21

Which muscle moves the eye directly medially?

Answer 21

Medial rectus

Question 22

Which muscle moves the eye directly laterally?

Answer 22

Lateral rectus

Question 23

How is the superior rectus muscle tested?

Answer 23

Move the eye laterally by lateral rectus muscle
then move eye superiorly, this will be by the superior rectus muscle
because the inferior oblique muscle can’t move eye any more laterally so it can’t move the eye superiorly either

Question 24

How is the inferior rectus muscle tested?

Answer 24

Move the eye laterally by lateral rectus muscle
then move the eye inferiorly, this will be by the inferior rectus muscle
because the superior oblique muscle can’t move the eye any more laterally so it can’t move the eye inferiorly either

Question 25

How is the medial rectus muscle tested?

Answer 25

Move the eye medially

Question 26

How is the lateral rectus muscle tested?

Answer 26

Move the eye laterally

Question 27

How is the superior oblique muscle tested?

Answer 27

Move the eye medially by medial rectus muscle
then move the eye inferiorly, this will be by the superior oblique muscle
because the inferior rectus muscle can’t move the eye any more medially, so it can’t move the eye inferiorly either

Question 28

How is the inferior oblique muscle tested?

Answer 28

Move the eye medially by the medial rectus muscle
then move the eye superiorly, this will be by the inferior oblique muscle
because the superior rectus muscle can’t move the eye any more medially, so it can’t move the eye superiorly either

Question 29

How are all the extra-ocular muscles tested in one go?

Answer 29

Make letter H with finger

ask patient to follow finger with eyes