Eye Movements Flashcards
what are the two components to stabilize image on retina?
- occulomotor system: eye in socket
head movement system: socket as whole with vestibular system
Saccades does what to image?
shift fovea rapidly to new target
what does smooth pursuit do?
keeps image of moving target on fovea
what does optokinetic movements do?
holds image still during sustained head rotation
6 extraocular muscles:
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
Inferior Oblique
superior Oblique
Superior oblique movements?
torsion and depression adduction
inferior oblique movements?
torsion and elevation
Superior Oblique muscles innervated by?
trochlear: CNIV
Lateral Rectus muscle innervated by?
Abducens: CN VI
trochlear CN IV innervates which superior oblique?
the CONTRALATERAL one…
what connects white matter tracts between cranial nerve nuclei?
medial longitudinal fasciculus (MLF)
what reticular formation in the pons for coordinated eye movements?
pontine paramedian reticular formation
what reticular formation in the midbrain for coordinated eye movements?
mesencephalic paramedian reticular formation
What does Pontine RF coordinate? which nerves?
horizontal gaze
(MR)CN III and (LR)CNVI
what does midbrain RF coordinate?
vertical gaze
(SO) CN IV and (SR)CN III
two kinds of neurons fire during horizontal saccades?
burst neurons before movement
omnipause neurons fire when eye not moving
Omnipause neurons do what?
inhibit via GABA
Burst neurons do what kind of signalling?
excitatory for ipsilateral abducens
inhibitory for contralateral abducens
what do you need for neural control of saccades?
simultaneous burst and inhibition of omnipause
eye movements ultimately driven by?
behaviour
what drives brainstem gaze centres? 5 things
frontal eye fields post parietal cortex superior colliculus basal ganglia cerebellum
which nerves needed coordinates head and eye movements together?
vestibulocochlear to medulla nuclei with CNIII, CNVI nuclei
