Pediatrics and Strabismus Vol. 1

Question 1

What differentiates a phoria from a tropia?

Answer 1

Presence or absence of fusional control

Question 2

What angle does the inferior oblique muscle form with the visual axis in primary position?

Answer 2

51 degrees

Question 3

What is the only rectus muscle that does not have an oblique muscle running tangential to it?

Answer 3

Medial rectus

Question 4

What angle does the superior rectus muscle make with the visual axis?

Answer 4

23 degrees

Question 5

What is the function of the superior rectus muscle primary, secondary, and tertiary action in primary position?

Answer 5

Primary - elevation Secondary- intorsion Tertiary- adduction

Question 6

What angle does the inferior rectus muscle form with the visual axis?

Answer 6

23 degrees

Question 7

What is the function of the inferior rectus muscle primary, secondary, and tertiary action in primary position?

Answer 7

Primary- depression Secondary - extorsion Tertiary- adduction

Question 8

What is the function of the superior oblique muscle primary, secondary, and tertiary action in primary position?

Answer 8

Primary - intorsion Secondary - depression Tertiary- abduction

Question 9

What angle does the superior oblique muscle form with the visual axis in primary position?

Answer 9

51 degrees

Question 10

What is the function of the inferior oblique muscle primary, secondary, and tertiary action in primary

Answer 10

Primary- extorsion Secondary - elevation Tertiary- abduction

Question 11

Which extraocular muscle has the longest tendon?

Answer 11

Superior oblique (26 mm)

Question 12

Which extraocular muscle has the shortest tendon?

Answer 12

Inferior oblique (1 mm)

Question 13

What is the primary arterial supply to the extraocular muscles?

Answer 13

Muscular branches of the ophthalmic artery

Question 14

What are the two major branches of the muscular branches of the ophthalmic artery?

Answer 14

Medial and lateral muscular branch

Question 15

What four muscles are supplied by the lateral muscular branch of the ophthalmic artery?

Answer 15

1. Lateral rectus 2. Superior rectus 3. Superior oblique 4.Levator palpebrae

Question 16

What three muscles are supplied by the medial muscular branch of the ophthalmic artery?

Answer 16

1. Inferior rectus 2.Medial rectus 3. Inferior oblique

Question 17

What artery partially supplies the lateral rectus muscle?

Answer 17

Lacrimal artery

Question 18

What artery partially supplies the inferior rectus and inferior oblique muscle?

Answer 18

Infraorbital artery

Question 19

Which arteries are carried by each rectus muscle and supply blood to the anterior segment?

Answer 19

Anterior ciliary arteries

Question 20

Which rectus muscle carry the bulk of the anterior ciliary arteries?

Answer 20

Superior and inferior rectus muscle

Question 21

What does the venous drainage system of the extraocular muscles drain into?

Answer 21

Superior and inferior orbital veins

Question 22

What is the posterior attachment of Tenon’s capsule?

Answer 22

Optic nerve sheath

Question 23

What is the anterior attachment of Tenon’s capsule?

Answer 23

Intermuscular septum (3 mm from the limbus)

Question 24

Where do the extraocular rectus muscles penetrate Tenon’s capsule?

Answer 24

10 mm posterior to their insertions

Question 25

What structure separates the extraocular muscles from the orbital fat and structures outside the muscle cone?

Answer 25

Tenon's capsule

Question 26

What structure separates the intraconal fat pads from the extraconal fat pads?

Answer 26

Intramuscular septum

Question 27

What forms Lockwood's ligament?

Answer 27

Fusion of the muscle capsule of the inferior oblique and inferior rectus muscle

Question 28

What does Lockwood's ligament connect to?

Answer 28

Lower eyelid retractors

Question 29

What structure separates the intraconal orbital fat from the sclera?

Answer 29

Tenon's capsule

Question 30

Where does the extraconal orbital fat and anteriorly?

Answer 30

10 mm from the limbus

Question 31

Approximately how far an instrument must be thrust posterior to the rectus muscles insertion to cause damage to their nerves?

Answer 31

26 mm

Question 32

Which cranial nerve lies outside the muscle cone and is NOT affected by a retrobulbar block?

Answer 32

CN IV

Question 33

Which extraocular muscle nerve can also cause pupil abnormalities if damaged?

Answer 33

Nerve to the inferior oblique muscle

Question 34

Which extraocular muscle surgeries may also cause palpebral fissure changes?

Answer 34

Superior and inferior rectus surgery

Question 35

What vascular complication must be considered when performing simultaneous surgery on 3 rectus muscles, especially in older patients?

Answer 35

Anterior segment ischemia

Question 36

What complication may occur if Tenon's capsule is penetrated 10 mm or more posterior to the limbus?

Answer 36

Prolapse of orbital fat

Question 37

Where is the sclera the thinnest?

Answer 37

Posterior to the rectus muscle insertions