Eye Movements Active Learning

Question 1

Where will the eye go from neutral if the occulomotor nerve is damaged? What iwll happen to the pupil?

Answer 1

It will go lateral and down - this is because the superior oblique and lateral rectus are still working

the pupil wil dilate

Question 2

Where will the eye go from neutral if CNIV is damaged?

Answer 2

It will go slightly up and lateral - this is because the superior oblique is not working and the inferior oblique can work unoposed

Question 3

Where will the eye move from neutral if CNVI is damaged?

Answer 3

medially

the lateral rectus won’t be working, so the medial rectus can work unopposed

Question 4

What is the purpose of saccadic movements?

Answer 4

they are rapid, jerky movements that bring the image of a new object onto the fovea - allows us to quickly scan points on an image to capture salient features like on a new face

Question 5

What are smooth pursuit eye movements for?

Answer 5

it’s eye movements that keep a moving image centered on the fovea - it’s tracking

Question 6

Why is vestibulo-ocular gaze importatn?

Answer 6

it keeps an image steady on the fovea during head movements

Question 7

What type of gaze keeps the image on the fovea when the object is moving nearer or farther away?

Answer 7

vergence

Question 8

What is the important role of the medial longitudinal fasciculus in occular reflexes?

Answer 8

it distributes sensory input to the motor nuclei on both sides of the brain, allowing the eyes to communicate and coordinate their movements.

it yokes the motor nuclei of CN3, CN4, CN6 and integrates movements directed by the frontal eye fields and vestibular informaiton from CN8

Question 9

What is the visual pathway for the saccadic gaze system?

Answer 9

Higher centers like the frontal eye fields, retina, and auditory system signal the gaze centers

these signal the ipsilateral and contralateral muscles via the MLF such that you get conjugate movement of the eyes

visual input –> superior colliculus –> lateral gaze centers in the paramedian pontine reticular formation –> fibers travel to th eipsilateral abducens nucleus and cross to the contralateral MLF to ascend to the oculomotor nucleus to conjugate movement gaze ot the right

Question 10

Describe the pathway of information for smooth pursuit.

Answer 10

1. signals from retina go to primary visual cortex
2. fro primary to the middle temporal cortex, which responds to direction of movement
3. frontal pursuit area integrates and responds to the directional movement
4. ongoing visual input to the superior colliculus results in activation
5. MLF brings the signals to the appropriate extraocular muscles