visual motor systems Flashcards
frontal eye field is a
PRE-MOTOR area, and is brodman areas 6 and 8 (depends on textbook)
frontal eye fields receive target location from__ and project to___
- visual association cortex
- project to horizontal and vertical gaze centers of superior colliculus
3 types of eye movemtnts that direct targets to the fovea?
- SACCADES=> rapid mvmt toward new targets (conjugate)
- SMOOTH PURSUIT=>slower mvmts that follow moving targets (conjugate)
- VERGENCE=> mvmts that adjust the eyes toward near and far objects (disconjugate)
vestibulo-ocular reflex fxn
compensate for ACCELLERATION
aka–to keep things on your fovea –“foveation”
optokinetic reflex fxn
compensates for mvmt of the entire visual field
aka–holds images STEADY during sustained head rotation
pupillary light reflex fxn
maintains retinal illumination (4 neuron chain with ciliary ganglion and SHORT ciliary nerves)
blink reflex fxn
protects the eye
M1 (area 4)
random mvmts
SM (area 6)
planned mvmts
nuclei in the pons that have to do with visual system
- PPRF,
- abducens,
- MLF
nuclei in the midbrain that have to do with the visual system
- MLF,
- occulomotor nucleus,
- trochlear nucleus,
- nuclei of Cajal and riMLF (vertical eye mvmts)
two kinds of eye movement pathways
- nuclear and infranuclear pathways ==> brainstem nuclei and peripheral parts of CNIII, IV, VI
- supranuclear pathways ==> brainstem and forebrain circuits
what are frontal eye fields for in eye movements
- remembered movements,
- scanning for areas of interest
- suppressing uninteresting things
superior colliculus involvement in eye movements
- reflexive ORIENTATING. this spot has a map of your visual field so that if you see something interesting, your eye can accurately direct the fovea to that location
what are the only two muscles that do NOT pull the eye at a WEIRD angle
- lateral rectus
- medial rectus
what muscles and CN do you use for STRAIGHT and UPWARD gaze
- superior oblique (CN IV)
- superior rectus (CN III)
Hering’s law
during conjugate eye mvmts, the YOKED muscle pair receives EQUAL innervation so the eyes move TOGETHER
course of CNIII
- lateral wall of cavernous sinus (topmost nerve)
- receives nn from carotid plexus and V1
- enters s. orbital fissure THRU annulus
- DIVIDES to sup. and inf.
course of CNIV
- lateral wall of cavernous sinus below CNIII
- crosses III, enters s. orbital fissure THRU annulus
- has communications with CAVERNOUS plexus and V1
course of abducens nerve
- WITHIN cavernous sinus, lateral and inferior to ICA
- enters s. orbital fissure THRU annulus
- has communications with CAVERNOUS plexus and V1
horizontal gaze center
frontal eye fields and superior colliculus.
BUT. thats NOT the only function of these two things. they can do all the mvmts
three kinds of neurons in PPRF
excitatory burst => to abducens nucleus
inhibitory burst => to other abducens nucleus
omnipause neurons => allow your eyes to pause
visual deficit if you have demeylination in ventral pons
ipsilateral abducens nerve palsy
superior tarsal muscle
Innervation?
syndrome?
sypathetic fibers
horners syndrome. if the lesion is in the spinal cord or the superiro cervical ganglion, its full blown. if its after the ganglion, you ususally don’t have anhydrosis
