Eye Movements

Question 1

what are the different classes of eye movements? (7)

Answer 1

Vestubular
Visual fixation
Optokinetic
Smooth pursuit (versions)
Nystagmus (quick phases)
Saccades(versions)
Vergence

Question 2

What are ductions? What types are there? (4)

Answer 2

Ductions are the movement of one eye. This is not normal but are useful when thinking about the movement of a single eye.
Types: Adduction, Abduction, Elevation and depression

Question 3

What are versions?

Answer 3

Conjugate movements. Both eyes moving in the same direction. When there are abnormalities in verisons we test ductions to determine which eye/muscle is affected

Question 4

What are the types of versions? (9)

Answer 4

Primary gaze
Dextroversion
Laevoversion
Elevation
Dextroelevation
Laevoelevation
Depression
Dextrodepression
Laevodepression

Question 5

What is vergence? What types of vergence are there? (2)

Answer 5

Vergence is when the eyes move in different directions. Types: convergence and divergence

Question 6

What are torsions? What are the types of torsions?

Answer 6

Torsional movements rotate the eye. Types: intorsion and extorsion

Question 7

What is the action of the medial rectus muscle?

Answer 7

Adduction

Question 8

What is the action of the lateral rectus muscle?

Answer 8

Abduction

Question 9

What is the action of the inferior rectus muscle?

Answer 9

Primary: depression
Secondary: extrosion
Tertiary: adduction

Question 10

What is the action of the superior rectus muscle?

Answer 10

Primary: elevation
Secondary: intorsion
Tertiary: adduction

Question 11

What is the action of the inferior oblique muscle?

Answer 11

Primary: extorsion
Secondary: elevation
Tertiary: abduction

Question 12

What is the action of the superior oblique?

Answer 12

Primary: intorsion
Secondary: depression
Tertiary: abduction

Question 13

What is Hering’s Law of equal innervation?

Answer 13

That equal and simultaneous innervation occurs for yoke muscles during conjugate eye muscles

Question 14

What is Sherrington’s Law of reciprocal innervation?

Answer 14

That increased innervation to an EOM is accompanied by a reciprocal decrease of innervation to its agonist. e.g when looking right the medial rectus is relaxed

Question 15

What are saccades? What are the types of saccades?

Answer 15

The eyes moving from one space in the visual field to another without following n object. Types: visually guided, reflective, scanning, anti-saccade, memory guided and predictive

Question 16

What are saccadic controllers?

Answer 16

They project to gaze centres in the brain stem.

Question 17

What are smooth pursuits?

Answer 17

Smooth eye movements to track a moving target

Question 18

What is optokinetic nystagmus?

Answer 18

an involuntary tracking movement which is elicted when a large portion of the visual field moves informly across the retina

Question 19

What is the vestibulo-ocular reflex?

Answer 19

It stabilises the eye when the head assumes different positions. The vestibular systems respond to angular and linear components of head motion