Visual tracts

Question 1

where is the object of attention centered at within the retina

Answer 1

fovea centralis and macula lutea

Question 2

in what area of the eye are photoreceptors absent

Answer 2

optic disc (medial to the macula)

Question 3

what are the two zones of the visual fields

Answer 3

binocular zone (seen by both eyes)
mono-ocular zone (seen by only R/L eye)

Question 4

what is a retinal field

Answer 4

the location on the retina where an object in the visual field is projected

Question 5

what is the optic disc

Answer 5

the region where retinal axons leave the eye as the optic nerve

Question 6

how is the image formed on the retina oriented

Answer 6

inverted along lateral and vertical axis

Question 7

does the nasal or temporal half of retinal axons decussate at the optic chiasm

Answer 7

nasal half decussates to contralateral optic tract

Question 8

what fibers are found within each optic tract

Answer 8

fibers from ipsilateral temporal retina and contralateral nasal retina

Question 9

what does partial decussation of retinal fibers facilitate

Answer 9

depth perception

Question 10

where does the optic tract terminate

Answer 10

lateral geniculate nucleus (LGN)

Question 11

what forms the dorsal and lateral borders of the lateral geniculate nucleus

Answer 11

outgoing optic radiations

Question 12

what forms the ventral base of the LGN

Answer 12

incoming optic tract

Question 13

what are the first and second layers of the LGN called

Answer 13

magnocellular layers

Question 14

what are the 3rd-6th layers of the LGN called

Answer 14

parvocellular layers

Question 15

which layers of the LGN receive inputs from rods

Answer 15

magnocellular layers

Question 16

which layers of the LGN receive inputs from cones

Answer 16

parvocellular layers

Question 17

which layers of the LGN have larger receptive fields and are sensitive to moving stimuli

Answer 17

magnocellular layers

Question 18

which layers of the LGN have smaller receptive fields and are sensitive to color and stationary stimuli

Answer 18

parvocellular layers

Question 19

which layers of the LGN have thicker, faster conducting axons

Answer 19

magnocellular layers

Question 20

where do axons from the temporal retina terminate

Answer 20

layers 2, 3, 5 of the ipsilateral LGN

Question 21

where do axons from the nasal retina terminate

Answer 21

layers 1, 4, 6 of the contralateral LGN

Question 22

what is an optic radiation

Answer 22

bundle of myelinated extensions from secondary neurons of LGN

Question 23

where does the optic radiation go

Answer 23

to the primary visual cortex (upper and lower banks of the calcarine sulcus AKA lingual gryrus and cuneus)

Question 24

fibers from which quadrant of the visual field go to the cuneus

Answer 24

lower quadrant of contralateral hemifield (dorsomedial LGN)

Question 25

fibers from which quadrant of the visual field go to the lingual gyrus

Answer 25

upper quadrant of contralateral hemifield (ventrolateral LGN)

Question 26

what is the path of fibers conveying information from the macula and fovea

Answer 26

central LGN => caudal visual cortex (posterior occipital pole)

Question 27

what is meyer's loop

Answer 27

an arch into the temporal lobe by the axons carrying information from the superior part of the visual field

Question 28

where does meyer's loop terminate

Answer 28

below the calacarine sulcus

Question 29

the left upper quadrant of the visual field would be represented in what area of the visual cortecx

Answer 29

right lower quadrant (opposite that of the visual field)

Question 30

what brodmann's area corresponds to the primary visual cortex

Answer 30

17

Question 31

what brodmann areas make up the visual association cortex

Answer 31

areas 18 and 19

Question 32

what function does the superior colliculus have in the visual system

Answer 32

directing eye movements

Question 33

what function does the pretectal area have in the visual system

Answer 33

pupillary light reflex

Question 34

pupillary constrictor muscles receive PNS innervation from what nuclei

Answer 34

edinger-westphal nucleus

Question 35

pupillary constrictor muscles receive SNS innervation from what nuclei

Answer 35

superior cervical ganglion

Question 36

where do preganglionic cholinergic motor neurons travel and synapse

Answer 36

travel w/ ipsilateral CN III | synapse in ciliary ganglion

Question 37

where do postganglionic cholinergic motor neurons travel

Answer 37

send axons via short ciliary ns to ciliary ms. and pupillary constrictors

Question 38

mydriasis and paralysis of accomodation are caused by a lesion of what structure

Answer 38

ipsilateral CN III

Question 39

how will partial optic nerve damage present when testing pupillary reflex

Answer 39

shining light in eye ipsilateral to lesion => diminished constriction of both eyes light in eye contralateral to lesion => normal reflex

Question 40

how will total optic nerve damage present when testing pupillary reflex

Answer 40

neither direct or consensual reflex of affected eye

Question 41

how will posterior midbrain damage present when testing pupillary reflex

Answer 41

weakened pupillary reflex bilaterally

Question 42

how will partial CN III damage present when testing pupillary reflex

Answer 42

direct and consensual response lost ipsilaterally, present contralaterally

Question 43

what is hemianopia

Answer 43

blindness in one-half of visual field

Question 44

what is quadrantanopia

Answer 44

blindness in one quadrant of visual field

Question 45

what is homonymous visual fields

Answer 45

conditions in which visual field loss is similar in both eyes

Question 46

what is heteronymous visual fields

Answer 46

conditions in which eyes have non-overlapping field losses

Question 47

what is macular sparing

Answer 47

visual field loss the preserves vision in the center of visual field

Question 48

where would a deficit be expected if damage is anterior to optic chiasm

Answer 48

only ipsilateral eye

Question 49

what kind of deficit would be expected if damage is at the optic chiasm

Answer 49

heteronymous deficit (non overlapping visual field loss)

Question 50

what kind of deficit would be expected if damage is behind the optic chiasm

Answer 50

homonomyous deficit (overlapping visual field loss)

Question 51

associative visual agnosia is caused by occlusion of what artery

Answer 51

PCA

Question 52

what structures are infarcted in associative visual agnosia

Answer 52

left occipital lobe and posterior corpus callosum

Question 53

what is associative visual agnosia

Answer 53

disconnection of language area from visual association cortex

Question 54

how does associative visual agnosia present

Answer 54

pt cannot name or describe object in visual field, but can recognize and demonstate its use compromised reading and writing