Pediatrics: Anatomy of Extraocular Muscles

Question 0

50

Answer 0

maximum motion in degrees of the eye in any direction

Question 1

IO

Answer 1

the branch of cranial nerve III that feeds this muscle carries the parasympathetics

Question 2

20

Answer 2

maximum motion in degrees of the eye in any direction under normal conditions before head turning occurs

Question 3

MR

Answer 3

the only rectus muscle that does not have an oblique muscle running tangential to it (making procedures easy but identification potentially tough)

Question 4

23

Answer 4

angle between the axis of the SR/IR and the optical axis of the eye (in degrees)

Question 5

intorsion

Answer 5

secondary action of the SR

Question 6

adduction

Answer 6

tertiary action of the SR

Question 7

tertiary

Answer 7

which action of the SR and IR is shared (primary, secondary, tertiary)

Question 8

51

Answer 8

angle of the tendon of the SO/IO with respect to the visual axis (in degrees)

Question 9

false

Answer 9

TRUE or FALSE the tendon if the SO passes superiorly to the SR

Question 10

intorsion

Answer 10

primary action of the SO

Question 11

depression

Answer 11

secondary action of the SO

Question 12

abduction

Answer 12

tertiary action of the SO

Question 13

tertiary

Answer 13

which action of the SO and IO is shared (primary, secondary, tertiary)

Question 14

vertical

Answer 14

rectus muscles that carry the bulk of the blood supply to the anterior segment

Question 15

orbital, global

Answer 15

two layers of the extraocular muscles

Question 16

Tenon’s capsule

Answer 16

the envelope within which the eyeball moves

Question 17

elastic

Answer 17

type of connective tissue in Tenon’s

Question 18

smooth muscle

Answer 18

rectus muscle pulleys contain this tissue

Question 19

intermuscular septum

Answer 19

thin layer of tissue that underlies the conjunctiva, spans between the rectus muscles, and separates the intraconal fat pads from the extraconal fat pads

Question 20

Lockwood’s ligament

Answer 20

fuses the IO muscle capsule (but not the muscle itself) with with the IR muscle capsule

Question 21

40 mm

Answer 21

length of active muscle of rectus muscles

Question 22

32 mm

Answer 22

length of active muscle of SO

Question 23

37 mm

Answer 23

length of active muscle of IO

Question 24

26 mm

Answer 24

how far back from the insertion of the a rectus muscle does the nerve insert

Question 25

CN IV

Answer 25

which nerve (due to its extraconal location) would not be affected by a retrobulbar block

Question 26

IO

Answer 26

the nerve supplying this muscle is most easily damaged during surgery

Question 27

muscle capsule

Answer 27

“slipped muscle” is caused by suture of only this to the globe

Question 28

muscle capsule

Answer 28

keeping this intact keeps a bloodless field and minimizes risk of adhesion formation during EOM surgery

Question 29

resection

Answer 29

the intermuscular septum needs to be dissected during this type of surgery

Question 30

10 mm

Answer 30

fatty prolapse may be caused by violation of Tenon’s capsule more than this distance from the limbus

Question 31

MR

Answer 31

surgery on this extraocular muscle is the easiest because its course is not crossed by any other muscle (it is also easier to get lost in surgery though)

Question 32

medial

Answer 32

which muscular artery is of larger caliber, the medial or the lateral?

Question 33

vertical

Answer 33

which rectus muscles carry the major portion of the blood supply to the anterior segment, the vertical or the horizontal?

Question 34

inferior division of CN III, medial muscular branch

Answer 34

this nerve and this artery perfectly overlap in terms of EOMs supplied

Question 35

inferior oblique, inferior rectus

Answer 35

these EOMs are also supplied by the inferior orbital artery