Visual Pathways

Question 1

what controls how much light is brought into the eye?

Answer 1

dilator muscle and sphincter

Question 2

T/F, each eye has a blind spot caused by the formation of the optic nerve/central retinal as it exits the eye?

Answer 2

T

Question 3

how many degrees is the blind spot from the center of the eye?

Answer 3

15 degrees

Question 4

hemianopias are vertical?

Answer 4

yes, not horizontal

Question 5

temporal retinal fibers see left or right visual field in the right eye?

Answer 5

left visual field

Question 6

nasal retinal fibers will see the left or right visual field in the right eye?

Answer 6

right visual field

Question 7

optic tracts travel ipsilaterally or contralaterally to the LGN in the thalamus?

Answer 7

ipsilaterally, note that the nasal fiber decussates and the temporal fibers do not (occurs at the optic chiasm from optic n)

Question 8

from the thalamus, where do the optic radiations travel?

Answer 8

to the occipital cortex, optic radiations have both temporal and parietal portions

Question 9

what is the geniculostriate pathway?

Answer 9

relays in the lateral geniculate nucleus and continues to the primary visual cortex

Question 10

what are the two layers of cells at the LGN?

Answer 10

magnocellular layer: receives input from the ganglion M cells
parvocellular layer: receives input from the ganglion P cells

Question 11

what are the extrageniculate pathways?

Answer 11

bypass the LGN and go to the superior colliculus

Question 12

what are the optic radiations?

Answer 12

fibers from the LGN that relay back to the primary visual cortex

the inferior fibers (meyer’s loop) pass through the temporal lobe

Question 13

optic radiations receive information from what quadrant of the visual field?

Answer 13

upper quadrant

Question 14

in terms of optic radiations, superior visual field is seen by inferior or superior retina? where does it travel?

Answer 14

inferior retina and travels through thalamus before becoming part of the Meyer’s loop

Question 15

where does the Meyer’s Loop travel?

Answer 15

to the inferior aspect of the calcarine fissure

Question 16

superior fibers of the optic radiations pass through what?

Answer 16

the parietal lobe and receive information from the lower quadrant of visual field

Question 17

where do the optic radiations ultimately go through?

Answer 17

visual cortex near the calcarine sulcus

Question 18

only fibers from here decussate at optic chiasm?

Answer 18

nasal retina

Question 19

lesions at the optic chiasm cause what?

Answer 19

bilateral temporal hemianopia

Question 20

this medical condition is due to a loss of lateral peripheral vision at the optic chiasm (most commonly the pituitary hemianopia)

Answer 20

bilateral temporal hemianopia

Question 21

if lesion on optic radiation/optic tract of right hemisphere, what is this medical condition called?

Answer 21

left homonymous hemianopia

Question 22

if lesion occurs in temporal lobe?

Answer 22

superior quadrantanopia

Question 23

this helps to converge the images seen by both eyes into one image?

Answer 23

ocular dominance column, so this is active to constantly integrate images from the right eye and the left eye

Question 24

T/F, high fidelity mapping is always maintained throughout the visual pathway?

Answer 24

T, different cell ganglion cells in the retinal layer always travel through the same pathway to end up in the visual cortex to be processed

Question 25

what cranial nerves make up the vestibulocoular movements?

Answer 25

combine CN6(lateral rectus) w CN 3(rotation of the head) and CN8 (rotation of the head) and so this is just movement of the head to the side while still maintaining focus on a single specific object

Question 26

what is the effect of visual light reflexes?

Answer 26

light shined into one eye causes direct constriction of eye pupil with light and consensual constriciton of pupil of other eye and requires CN II and CN III

Question 27

this medical condition is when you miosis with pupil that is slow to dilate, mild ptosis, ipsilateral anhidrosis?

Answer 27

horner syndrome

Question 28

this medical condition is caused by neurosyphilis?

Answer 28

Argyll Robertson Pupil (prostitutes pupil) so pupil is small and constricts poorly to direct light

Question 29

this medical condition affects pupil of eye and the ANS, one eye with a pupil larger than normal that constricts slowly in bright light; absence of DTR's usually achilles

Answer 29

Holmes Adie Syndrome

Question 30

this medical condition is when there is segmental anhidrosis or hypohydrosis along with symptoms of Adie's syndrome (loss of DTR and Adie's pupil) cranial post ganglionic parasympathetic and sympathetic dysfunction in association with widespread autonomic failure

Answer 30

Ross syndrome