3a. Extraocular Ms And BSV

Question 1

Which extraocular muscle is responsible for intorsion, depression, and abduction?

Answer 1

Superior oblique

Question 2

What is the primary action of the lateral rectus?

Answer 2

Abduction

Question 3

The only extraocular muscle not originating from the common tendinous ring is?

Answer 3

Inferior oblique

Question 4

Which nerve supplies the superior oblique muscle?

Answer 4

Trochlear nerve (CN IV)

Question 5

What is Sherrington’s law of reciprocal innervation?

Answer 5

Increased innervation to a muscle is accompanied by decreased innervation to its antagonist

Question 6

Which law states that yoke muscles in each eye receive equal innervation?

Answer 6

Hering’s law of equal innervation

Question 7

What are the primary, secondary, and tertiary actions of superior rectus?

Answer 7

Elevation (primary), intorsion (secondary), adduction (tertiary)

Question 8

Which muscle is tested by asking the patient to look laterally and then upward?

Answer 8

Superior rectus

Question 9

What is binocular single vision (BSV)?

Answer 9

The ability to perceive a single image using both eyes simultaneously

Question 10

What test is commonly used to detect suppression in binocular vision?

Answer 10

Worth four-dot test

Question 11

Which muscle causes extorsion, elevation, and abduction of the eyeball?

Answer 11

Inferior oblique

Question 12

What is the angle between the visual axis and the optical axis called?

Answer 12

Angle alpha

Question 13

How many types of binocular single vision are there?

Answer 13

Three (simultaneous perception, fusion, and stereopsis)

Question 14

What is the insertion distance of the medial rectus from the limbus?

Answer 14

5.5 mm (Mnemonic: MILS – Medial 5.5, Inferior 6.5, Lateral 6.9, Superior 7.7 mm)