Eye movements [3]

Question 1

Near/accomodation reflex

Answer 1

• Medial recti contract
• Pupils contrict → increase depth of field
• ciliary m. constrict

Question 2

What type of eye movement is completely dependent on visual input?

Answer 2

Smooth pursuits

Question 3

the pattern generators for vertical and horizontal saccades are found near where?

Answer 3

Vertical: near occulomotor nuclei

Horizontal saccades:
in reticular formation, near abducens nucleus

Question 4

two important control centers for saccades

Answer 4

cortex

Superior colliculus

Question 5

What happens to your ability to generate saccades if you have damage to:

1. Frontal eye fields
2. superior colliculus
3. both

Answer 5

1. Frontal eye fields
   - temporary loss in ability to generate saccades
2. superior colliculus
   - Saccades are less accurate and occur less often
3. both
   - permanent loss in ability to make saccades

Question 6

Horizontal saccades are drive (pick one) contralaterally/ipsilaterally

Answer 6

contralaterally,

saccade to the left is driven by activity in the Right from frontal field.

Question 7

Vestibular input VOR conxn

Answer 7

Look to the right → head rotation is signaled by horizontal canals (fluid in horiz semi-circ canal lags behind → deflection of cupula in both horiz canals → R horizontal canal (depolariz), L horz canal; (hyperpol) → excitation signals vestibular nuclei → (cross) MLF → abducens nucleus (cross) → MLF → occulomotor nucleus → medial rectus

or abducens →lateral rectus → motor neurons.

Question 8

Can vestibular input occur in the dark with no visual input at all?

Answer 8

Yes

Question 9

Internuclear ophthalmoplegia INO

Answer 9

common in pts with MS

• MLF damage
• Eye does not work
• convergenge works