W21-L9: Control of Eye movements Flashcards Preview

Matt's Block 06 - Neuro block > W21-L9: Control of Eye movements > Flashcards

Flashcards in W21-L9: Control of Eye movements Deck (16):
1

What are the two systems that stabilize an image of an object on the retina?

Oculomotor and Head-movement system

2

What is the Oculomotor system?

Moves the eyes in the orbit (whilst head is still)`

Involves extraocular muscles and neural pathways that coordinate movement of each eye.

3

What is the Head-movement system?

moves the eye sockets as a whole (whilst head moves).
Involves vestibular system as well as oculomotor system

4

Primary actions of recti

Superior Rectus: Elevation
Inferior Rectus: Depression
Medial rectus: Adduction
Lateral rectus: abduction

5

What is the function of Superior Oblique?

torsion (rotation), adduction and depression

6

What is the function of Inferior Oblique?

torsion, adduction and elevation

7

Why do muscles have multiple actions?

mulitple actions of the muscles on the eyeballs is due to the angle of insertion

8

What is the Medial longitudinal fasciculus?

White matter tract that connects the various cranial nerve nuclei

9

What is the Pontine paramedian reticular formation?

-Horizontal gaze centre
-coordination of MR and
LR of each eye
-coordination of CNIII & CNVI

10

What is the Mesencephalic paramedian reticular formation?

-Vertical gaze centre
-Coordination of SO and SR of each eye
-Coordination of CNIV and CNIII

11

What are the two types of neurones in the Pontine Paramedian reticular formation?

Burst neurones (drive contraction) which fire just before movement and omnipause neurones (inhibit contraction) which work all the time when not contracting

12

What is the neural control of saccades?

1. Excitatory burst neurones receive input from the cortex
2. Stimulates ipsilateral LR via abducens nucleus
3. Via MLF stimulates contralateral CN III nucleus and contralateral MR
4. Inhibitory burst neurones inhibit contralateral abducens via MLF which inhibits contralateral LR
5. Also via MLF ipsilateral CN III nucleus and MR are inhibited

13

Where do frontal eye fields control saccades?

controls saccades in the contralateral direction

14

What do Semicircular canals signal?

Head position

15

What does otolith signal?

Linear acceleration

16

What is the Vestibular-ocular reflex when looking to the left?

Left horiztonal semicircular canal signals to left vestibular nucleus- and then contralateral Nucleus of VI, stimulates LR (of Right eye) and stimulates contralateral (Left) CN III nucleus and MR.

Left vestibular nucleus also stimulates left (ipsilateral) CN III nucleus (MR)

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