22 JULY 2019 Flashcards
what happens when you have a CN VI dx
the eye with broken CN VI will stay straight when trying to look to the side
right internuclear opthlanoplagie
when CN is working but the MLF is broken so can’t move in conjugate fashion
what happens when you have a CN III:
one eye will be ABducted to the side because CN III isn’t working so doesn’t pull it to the front
what happens when you have a CN IV:
one eye wanders when you try to look down and across
palsy def (in this setting)
damage misfunction
misalignment acute phase is
diplopia
misalignment chronic phase
resolves dipoplia = suppressed vision from 1 eye = loss depth perception
optokinetic reflex:
stay focused on object of interest during slow head movements
optokinetic nystagmus:
when you have oscillations of the eye can be normal or abnormal
direction of gaze:
keeps objects in focus when they are moving
VOR involves what structures
inner ear: which detects movements of the head
and the semicircular canals
how do you test VOR:
make fast head movements
a real world example of VOR is
a movie steady cam - the steady cam is the VOR
VOR suppression:
when you purposefully stop the natural reflex of VOR
gaze stabilization:
movements that keep visual objects stable as we move through it
- keeps the world steady as I move through it
real world example of DSFX of gaze stabilization
the cops camera
smooth pursuits is
conscious optokinetic movemets where you are tracking a moving object
nystagmus description of movement:
slow then fast jerk
abnormal vs. normal nystagmus:
normal : VOR when head is moving
abnormal: when head is not moving
saccades:
eyes move between stationary objects
nystagmus def:
involuntary back adn forth movements of the eyes designed to keep visual field : world steady when we’re moving
physiologic nystagmus =
normal nystagmus = happens when you move your head
pathologic nystagmus =
abnormal nystagmus = happens when you are not moving
voluntary saccades happens when
we read a book or do we look between stationary objects
reflexic saccades happens when
superior colliculi kicks in the and you turn your head to an object moving
VOR piece of nystagmus is
slow - eyes lag behind
the saccade of nystagmus piece is
fast - eyes catch up
there are two pieces of nystagmus:
VOR piece - slow : eyes lag behind
saccades - fast: eyes catch up
two types of saccades
voluntary
reflexic
list the disorder of eye movements:
- CN
- MLF
- NMJ
- extrocular Mm
- vestibular
- cerebellum
motion sickness
due to conflicting between systems:
- we are not moving
- we are moving
why does sitting in the front help with car sickness:
eyes are better to detect motion
