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35 Cards in this Set
- Front
- Back
in general the primary visual pathway is made up of |
2 neuron pathway; retinal ganglion cells whose axons synapse in lateral geniculate nucleus (LGN); 2nd neuron axons form optic radiations to occipital lobe |
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rods versus cones |
rods= higher sensitivity, low light levels, monochromatic, peripheral vision (peripheral retina); cones= bright light, color, detailed central vision (macula) |
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normal color vision is what |
trichromatic aka requires all 3 types of cones (red, green, and blue) |
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dichromats |
difficulty distinguishing between 2 different colors; most common form is a red/green deficiency (problem with red or green pigment) |
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monochromats |
only see the world in grey; have only one cone pigment, or no cones and just rods, or even a cerebral deficit |
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what is dyschromatopsias and what are the 2 types |
inability to distinguish colors aka color blindness; hereditary= 5-6% of males have some color vision loss, usually is a red/green discrimination deficit, X-linked inheritance pattern; acquired= can be red/green or blue/yellow discrimination defect, sign of macular disease or optic nerve disease, e.g. optic neuritis |
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ishihara plates |
those color dot circles with the different colored dots tracing out a number; 'tell me what number you see if any' |
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the retinal ganglion cells have projections to where? |
lateral geniculate nucleus (which then goes to occipital cortex) (vision), or hypothalamus (suprachiasmatic nucleus) (circadian rhythms), or superior colliculus (coordination of head and eye movements), or pretectum (pupillary light reflex); HE SAID THESE ARE VERY IMPORTANT YOU NEED TO KNOW THESE |
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the pupillary light reflex path |
optic nerve --> optic chiasm --> crossing over occurs --> pretectum --> crossing over occurs --> edinger-westphal nuclei in pretectum --> joins CN3 --> ciliary ganglion --> pupillary sphincter muscle; so the input of bright light of course going to the occipital lobe but there is also a projection to this EW nucleus which then sends its own projection to the sphincter to constrict; keep in mind that this is partly the same tract as regular vision so there is crossing over so you do see some constriction in the eye that didn't have the pen light shown into it; HE SAID WE DO NEED TO KNOW THIS PATH AS WELL |
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the pituitary sits in what bony depression of the skull? |
sella turcica |
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the sella turcica is formed by what bone? |
sphenoid |
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how would a pit tumor cause bitemporal hemianopsia? |
upward expansion interrupts crossing fibers in optic chiasm |
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what is a quick, inexpensive method to test visual fields? |
confrontational method |
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blood supply of retina and optic nerve |
OPTHALMIC ARTERY; KNOW ALL THESE BLOOD SUPPLY QUESTIONS BECAUSE HE SAID IT WILL PROBABLY BE ON THE TEST |
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BLOOD SUPPLY OF OPTIC CHIASM |
BRANCHES FROM CIRCLE OF WILLIS |
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BLOOD SUPPLY OF OPTIC TRACTS AND LGN |
ANTERIOR CHOROIDAL |
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BLOOD SUPPLY OF OPTIC RADIATIONS |
MIDDLE AND POSTERIOR CEREBRAL |
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BLOOD SUPPLY OF VISUAL CORTEX |
POSTERIOR CEREBRAL |
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where does integration of input from both eyes occur |
mixing of the pathways doesn't occur until the occipital lobe (there is crossing over beforehand but the paths are still kept segregated) |
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what is binocular vision? |
steropsis aka depth perception which requires good visual acuity in each eye and good alignment; occurs by 3-6 months |
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what is strabismus? |
MISALIGNMENT of ocular axes; if this occurs in a baby it can be hard to form binocular vision |
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what is amblyopia? |
poor vision in an eye due to 'damage' to visual centers in the brain for that eye; the damage is the result of abnormal visual stimulation during the SENSITIVE PERIOD of visual development; one or sometimes both eye(s) will not have good visual acuity even after glasses correction; causes= SAD= Strabismus (misalignment), Asymmetry (e.g. refractive error), or Deprivation (e.g. cataract) |
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the secondary vision centers and what they are concerned with |
temporal cortex for object recognition (damage here causes visual agnosia, lesions do not result in loss of visual acuity); parietal cortex for visually guided behavior (lesions do not result in loss of object recognition or in loss of visual acuity) |
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what does the lens do to the visual info? and what about the info that reaches the brain? |
inverts and reverses the image on the retina; optic chiasm ensure that left vision goes to right brain and right vision goes to left brain |
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different parts of vision in the occipital lobe |
superior of the calcarine fissure is the inferior part of our vision (the floor if you will) and inferior of the calcarine fissure is the superior part of our vision (the sky if you will); posterior part of occipital lobe is the central (macular) vision) and anterior part of occipital lobe is the peripheral vision |
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KNOW THE LESIONAL DEFICITS SLIDE |
SLIDE 61 |
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visual field defect: SCOTOMA definition |
a small defect |
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visual field defect: ANOPSIA definition |
a large defect like hemianopsia |
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VISUAL ACUITY DEFINITION |
ability to see detail as measured on eye chart |
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DYSCHROMATOPSIAS DEFINITION |
inabillity to distinguish colors 'color blindness' |
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PERIPHERAL VISION DEFINITION |
detection of form and movement in outer visual fields |
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AGNOSIA DEFINITION |
inability to recognize or name objects |
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AMBLYOPIA DEFINITION |
poor vision in one or both eyes do to problems during visual development |
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STRABISMUS DEFINITION |
misaligment of the eyes, can be a cause of amblyopia |
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DIPLOPIA DEFINITION |
double vision, perception of 2 images form a single object |