Visual System Pathways Flashcards
What part of the thalamus do the cranial tracts terminate?
LGN (lateral geniculate nucleus)
What “Area” is the primary visual cortex?
Area 17
What “Areas” are the visual association cortex?
Areas 18 and 19
How many neurons does it take to get from the eye to the LGN?
3
What are the 1˚, 2˚, and 3˚ afferents from the eye?
1˚: receptors
2˚: bipolar cells
3˚: ganglion cells
Which cells form the optic nerve?
ganglion cells (3˚ retinal cells)
What are the two types of visual fields?
retinal and visual
Images are both ______ and ______
inverted and flipped
The optic nerve is an outgrowth of which embryological structure?
diencephalon
The optic chiasm sits on what cranial structure?
sella turcica
What structure is located immediately behind the optic chiasm
pituitary gland
The optic tract carries information from the contralateral/ipsilateral visual field
contralateral
What is retinotopic organization?
lower visual field located more medially
What is the name of the fiber bundle that runs from the LGN?
optic radiation
The sublenticular portion of the optic radiations carries 4˚ neuron fibers from what visual field?
upper visual field
The retrolenticular portion of the optic radiations carries 4˚ neuron fibers from what visual field?
lower visual field
What type of defect can occur after damage to either the sublenticular or retrolenticular lateral geniculate nucleus?
loss of 25% of visual field
The sublenticular optic tract carries axons to what structure?
lingual
The retrolenticular optic tract carries axons to what structure?
cuneate
The dorsal stream of the association visual cortex runs through what portion of the brain?
parietal/temporal cortex
The dorsal stream of the association visual cortex is responsible for what type of processing?
where?
The ventral stream of the association visual cortex runs through what portion of the brain?
inferior temporal cortex
The ventral stream of the association visual cortex is responsible for what type of processing?
what?
What is a homonymous defect?
either right or left visual field affected
Where is a homonymous defect usually located?
almost exclusively after the optic chiasm
Where is a heteronymous defect usually located?
almost exclusively at the optic chiasm
What is a heteronymous defect?
involves parts of both visual fields
