anatomy of the extraocular muscles

Question 1

what are the 4 rector muscles?

Answer 1

superior
inferior
medial
lateral rectus

Question 2

what are the 2 oblique muscles?

Answer 2

superior
inferior

Question 3

what are the 7 extraocular skeletal muscles?

Answer 3

4 rectus muscles
2 oblique muscles
levator palpebrae superioris

Question 4

what are the rectus and oblique muscles responsible for?

Answer 4

eye movement

Question 5

what is the role of levator palpebrae superioris?

Answer 5

superior eyelid movement

Question 6

where do all the rectus muscles originate?

Answer 6

common tendinous ring

Question 7

where do all the rectus muscles insert?

Answer 7

onto sclera

Question 8

where do the oblique muscles insert?

Answer 8

onto eyeball at oblique angle

Question 9

where does the superior oblique muscle originate from?

Answer 9

sphenoid bone

Question 10

where does the inferior oblique muscle originate from?

Answer 10

orbital plate of maxilla

Question 11

before inserting onto the eyeball, where does the tendon of the superior oblique pass through?

Answer 11

a trochlea (loop of connective tissue)

Question 12

what is the only muscle involved in raising the superior eyelid?

Answer 12

LPs

Question 13

where is the origin of the LPA?

Answer 13

lesser wing of sphenoid

Question 14

where does LPS insert?

Answer 14

skin and tarsus of superior eyelid

Question 15

what is Mueller’s muscle?

Answer 15

a collection of smooth muscle fibres in the superior tarsal muscle

Question 16

what does Mueller’s muscle assist with?

Answer 16

LPS in opening the eyelid

Question 17

what is the difference in innervation between Mueller’s muscle and LPS?

Answer 17

Mueller’s muscle - sympathetic fibres from superior cervical ganglion
LPS - CN III (oculomotor)

Question 18

what causes ptosis in Horner’s syndrome?

Answer 18

sympathetic innervation of Mueller’s muscle is compromised as Mueller’s muscle assists in opening eyelid

Question 19

which direction does the lateral rectus look?

Answer 19

laterally

Question 20

what supplies lateral rectus?

Answer 20

CN VI (abducent nerve)

Question 21

which direction does the superior oblique look?

Answer 21

medial, down

Question 22

what is superior oblique supplied by?

Answer 22

CN IV (trochlear nerve)

Question 23

what are all other muscles of the eye supplied by?

Answer 23

CN III (oculomotor)

Question 24

which two muscles don’t have secondary movements?

Answer 24

medial and lateral rectus

Question 25

where do all movements occur from?

Answer 25

primary position e.g. gaze directed forward

Question 26

what do we have to do to test movements of individual muscles?

Answer 26

line up gaze plane of muscles being tested to isolate muscle movements

Question 27

how do we test superior rectus muscle (oculomotor)?

Answer 27

ask patient to look laterally and upward

Question 28

how do we test inferior rectus muscle (oculomotor)?

Answer 28

ask patient to look laterally and downward

Question 29

how do we test lateral rectus muscle (abducent)?

Answer 29

ask patient to look laterally

Question 30

how do we test medial rectus muscle (oculomotor)?

Answer 30

ask patient to look medially

Question 31

how do we test inferior oblique muscle (oculomotor)?

Answer 31

ask patient top look medially and upward

Question 32

how do we test superior oblique muscle (trochlear)?

Answer 32

ask patient to look medially and downward

Question 33

what is the only movement lateral rectus can do?

Answer 33

abduct eyeball

Question 34

when in abduction, what is the only thing the superior rectus muscle can do?

Answer 34

elevate eyeball

Question 35

when in abduction, what is the only thing the inferior rectus can do?

Answer 35

depress eyeball

Question 36

what is the only thing the medial rectus muscle can do?

Answer 36

adduct eyeball

Question 37

when in adduction, what is the only thing the inferior oblique can do?

Answer 37

elevate eyeball

Question 38

when in adduction, what is the only thing the superior oblique can do?

Answer 38

depress eyeball

Question 39

what muscles are involved in pure elevation of the eye?

Answer 39

superior rectus and inferior oblique

Question 40

how do superior rectus and inferior oblique synergistically elevate eyes?

Answer 40

work as antagonistic rotators

Question 41

what muscles are involved in pure depression of the eye?

Answer 41

superior oblique and inferior rectus

Question 42

how do superior oblique and inferior rectus synergistically depress eyes?

Answer 42

work as antagonistic adductors/abductors