Control of Eye Muscles

Question 1

What nerves innervate what eye muscles

Answer 1

Lateral rectus: CN6
Superior oblique: CN4
All other muscles: CN3

Question 2

Horizontal eye movements involve what 2 muscles?

Answer 2

Lateral and medial rectus that need to move together

Question 3

Pathway of signals if you want to move your eyes to the left

Answer 3

Signal begins in the horizontal gaze center (PPRF) in the pons on the left
Sends neurons to the abducens nucleus (on left)
Sends neurons to lateral rectus on left eye
Neurons from the PPRF bifurcate and also innervate an interneuron in the abducens nucleus
This interneuron crosses the midline and travels in the MLF to the right oculomotor nucleus
This then sends a neuron to the medial rectus on the right eye
End goal: both eyes look left

Question 4

3 main types of eye movements

Answer 4

Saccades
Pursuit
Vestibulo-ocular reflex

Question 5

2 types of saccades

Answer 5

Volitional

Reflexive

Question 6

3 types of volitional saccades

Answer 6

Anti-saccade (look away from something)
Memory saccade (looking where something used to be)
Predictive saccade (involves the cerebellum - calculate the velocity of a rapidly moving object and move your eyes to where it will end up)

Question 7

Is pursuit to the right in the left or right frontal eye fields?

Answer 7

Right (opposite from saccades)

Question 8

Where is the

1. Horizontal gaze center
2. Vertical gaze center

Answer 8

1. Pons

2. Midbrain

Question 9

What does it tell us if the eyes can converge?

Answer 9

CN3 is okay!