Ductions, Versions, and Vergences

Question 1

What are ductions

Answer 1

The movements of ONE eye

Question 2

Ductions can be explained by

Answer 2

Rotations around one or more axes

Question 3

Fick’s axes (3)

Answer 3

X axis (horizontal, transverse)

• Divides eye into anterior and posterior halves
• Supraductions and infraductions

Y axis (sagittal, visual)

• Divides eye into medial and lateral parts
• Incycloduction (intorsion) and excycloduction (extorsion)

Z axis (vertical)
-Adduction and abduction

Question 4

If the course of the muscle is parallel to an axis…

Answer 4

Then no rotation around that axis can occur

Question 5

If the course of the muscle is perpendicular to an axis…

Answer 5

Then the only rotation for that muscle is around that axis

Question 6

Actions from primary gaze of the medial rectus

Answer 6

Perpendicular to the Z/vertical axis. So it is able to adduct the eye.

Question 7

Actions from primary gaze of the lateral rectus

Answer 7

Perpendicular to the Z/vertical axis. So it is able to abduct the eye.

Question 8

Actions from the primary gaze of the superior rectus

Answer 8

1. Supraduct
2. intortion
3. adduction

Question 9

Actions from the primary gaze of the inferior rectus

Answer 9

1. Infraduct
2. extortion
3. adduction

Question 10

Actions from the primary gaze of the superior oblique

Answer 10

1. Intorsion
2. Infraduct
3. abduction

Question 11

Actions from the primary gaze of the inferior oblique

Answer 11

1. Extortion
2. Supraduct
3. abduction

Question 12

Cardinal position of gaze

Answer 12

6 Positions of gaze isolates each EOM

Clinically useful to determine if each EOM is functioning properly.

Question 13

If exactly 23 degrees from the primary position,

Answer 13

The superior and inferior rectus are perpendicular to the horizontal axis and will supra duct (SR) and infra duct (IR) the eye

Question 14

If exactly 51-55 degrees from primary position

Answer 14

The superior oblique will infraduct and the inferior oblique will supraduct

Question 15

Agonist/antagonist pairs

Answer 15

Lateral rectus/medial rectus
superior rectus/inferior rectus
superior oblique/inferior oblique

Question 16

When an agonist contracts (Stimulated), its antagonist

Answer 16

relaxes (inhibited)

Question 17

Synergist

Answer 17

A muscle that works in concert with another muscle to generate movement.

Question 18

Versions

Answer 18

Movement of both eyes in the same direction

Question 19

Dextroversion

Answer 19

Both eyes move to the right

Question 20

Dextroelevation

Answer 20

Both eyes move up and to the right

Question 21

Dextrodepression

Answer 21

both eyes move down and to the right

Question 22

Levoversion

Answer 22

Both eyes move to the right

Question 23

Levoelevation

Answer 23

Both eyes move up and to the left

Question 24

Levodepression

Answer 24

Both eyes move down and to the left

Question 25

Elevation

Answer 25

Both eyes move up

Question 26

Depression

Answer 26

Both eyes move down

Question 27

Hering’s law of equal innervation

Answer 27

Pair of muscles receives equal and simultaneous excitatory or inhibitory signals (versions)

Question 28

Vergences

Answer 28

Movement of both eyes in opposite directions

Question 29

What occurs during convergence

Answer 29

Each eye is adducted to fixate at near target

Question 30

What occurs during divergence

Answer 30

Each eye is abducted to fixate at distance target