Extraocular Muscles

Question 1

What are the extraocular muscles

Answer 1

1. Levator palpebrae superioris
2. 4 Recti
3. Superior oblique muscle
4. Inferior oblique muscle

Question 2

Levator palpebrae superioris origin

Answer 2

Orbital roof in front of optic foramen

Question 3

Levator palpebrae superioris insertion

Answer 3

Under orbital roof into tarsus and skin of upper eyelid
Superior conjunctival fornix

Question 4

Levator palpebrae superioris nerve supply

Answer 4

Oculomotor 3rd cranial nerve

Question 5

Levator palpebrae superioris action

Answer 5

Elevates upper eyelid
Muscle deep part (muller’s muscle) is smooth and supplied by sympathetic fibers

Question 6

4 Recti origin

Answer 6

1. Common tendinous ring surrounding optic foramen and medial part of superior orbital fissure
2. Each arises from ring corresponding side
3. Lateral rectus has head from superior orbital fissure

Question 7

4 Recti insertion

Answer 7

Each passes forward to be inserted into sclera short distance behind corneoscleral junction (51/2-71/2mm)
MR: 51/2 mm
IR: 61/2 mm
LR: 7 mm
Sr: 71/2 mm

Question 8

4 Recti nerve supply

Answer 8

Oculomotor 3rd cranial nerve
Except lateral rectus: abducent 6th cranial nerve

Question 9

Lateral rectus muscle action

Answer 9

Moves eyeball lateral (abduction)

Question 10

Medial rectus muscle action

Answer 10

Moves eyeball medial (adduction)

Question 11

Movements of abduction and adduction occur around on…

Answer 11

Imaginary vertical axis

Question 12

Superior rectus muscle action

Answer 12

Moves eyeball upwards (elevates) and medial (adducts) with slight intorsion

Question 13

Inferior rectus muscle action

Answer 13

Moves eyeball downwards (depresses) and medial (adducts) with slight extorsion

Question 14

Movements of intorsion and extorsion occur around…

Answer 14

Imaginary anteroposterior diameter

Question 15

Movements of upwards and downwards occur around…

Answer 15

Imaginary transverse axis

Question 16

Superior oblique muscle origin

Answer 16

1. Orbital roof above and medial to optic foramen
2. Lies just above and medial superior rectus origin

Question 17

Superior oblique muscle insertion

Answer 17

Tendon passes forwards through Trochlea then curves backwards and downwards and lateral to insert into sclera behind eyeball equator

Question 18

Superior oblique muscle nerve supply

Answer 18

Trochlear 4th cranial nerve

Question 19

Superior oblique muscle action

Answer 19

Moves eyeballs downwards (depresses) and lateral (abducts) with intorsion

Question 20

Inferior oblique muscle origin

Answer 20

Floor of orbit just lateral to Nasolacrimal groove

Question 21

Inferior oblique muscle insertion

Answer 21

Muscle passes backwards and upwards and lateral below eyeball to insert into sclera behind eyeball equator

Question 22

Inferior oblique muscle nerve supply

Answer 22

Oculomotor 3rd cranial nerve

Question 23

Inferior oblique muscle action

Answer 23

Moves eyeball upwards (elevates) and lateral (abducts) with extorsion