ANAT visual tracts

Question 1

what forms the visual pathway

Answer 1

axons of ganglion cells and axons of higher order cells on which they synapse

Question 2

what is a visual field

Answer 2

area a person is able to see when both eyes are fixed in one position

Question 3

what is the optic disc

Answer 3

region where retinal axons leave the eye as the optic nerve

no photoreceptors present here, creates our blindspot

Question 4

fibers from where run in the optic tract

Answer 4

fibers from ipsilateral temporal retina

fibers from contralateral nasal retina

Question 5

where does the optic tract terminate

Answer 5

lateral geniculate nucleus (LGN)

Question 6

what forms the ventral base of the LGN

Answer 6

incoming optic tract (reticulogeniculate) fibers

Question 7

what forms the dorsal and lateral borders of the LGN

Answer 7

outgoing optic radiations

Question 8

magnocellular layers

Answer 8

layers 1 and 2 (ventral) of LGN
ganglion cell inputs relaying from rods
sensitive to moving stimuli

Question 9

parvocellular layers

Answer 9

layers 3-6 (dorsal) of LGN
ganglion cell inputs relaying from cones
responsive to stationary stimuli, high-acuity color vision

Question 10

pathway of temporal retina

Answer 10

remain ipsilateral and terminate in layers 2,3, and 5 of LGN

Question 11

pathway of nasal retina

Answer 11

cross and terminate in layers 1,4, and 6 of contralateral LGN

Question 12

fibers from the lower quadrant of the contralateral hemifields:
originate
where do they go

Answer 12

originate from dorsomedial portion of LGN
arch caudally to pass through retrolenticular limb of IC
target superior bank of calcarine sulcus, on the cuneus

Question 13

fibers from the upper quadrant of the contralateral hemifields:
originate
where do they go

Answer 13

originate from ventrolateral portion of LGN
arch rostrally, passing into white matter of temporal
lobe and looping, forming meyer loop
target inferior bank of calcarine sulcus, on lingual gyrus

Question 14

fibers from macula and fovea
originate
where do they go

Answer 14

originate from central regions of LGN

pass to caudal portions of visual cortex

Question 15

what composes the visual association cortex (extrastriate cortex)

Answer 15

areas 18, 19, and related parts of the temporal and parietal lobes

Question 16

other visual cortical areas 
and f(x)

Answer 16

superior colliculus: directing eye movements

pretectal area: pupillary light reflex

Question 17

congruous visual field deficit

Answer 17

visual field loss of one eye can be superimposed on that of the other eye (symmetrical)
the closer a lesion is to the visual cortex, the more congruous it is likely to be

Question 18

overarching concept of visual field deficits

Answer 18

damage anterior to chiasm affects only ipsilateral eye
damage at chiasm causes heteronymous deficits
damage behind chiasm causes homonymous deficits

Question 19

associative visual agnosia

Answer 19

infarction of the left occipital lobe and posterior corpus callosum
pt cannot name or describe an object in the visual field, but he can recognize and demonstrate its use