20 (pt 1) Visual System

Question 1

pupillary light reflex afferents

Answer 1

CN II

Question 2

pupillary light reflex efferents

Answer 2

CN III

Question 3

optic nerve lesion

Answer 3

ipsilateral blindness

Question 4

optic chiasm lesion

Answer 4

bitemporal hemianopsia

Question 5

optic tract lesion

Answer 5

contralateral homonymous hemianopsia

Question 6

Meyers loop lesion

Answer 6

contralateral superior homonymous quandrantinopia

Question 7

visual cortex lesion

Answer 7

contralateral homonymous hemianopsia with macular sparring

Question 8

oculomotor nerve lesion

Answer 8

ipsilateral
“Down and out” gaze
Ptosis
Dilated, non-reactive pupil
Double vision (diplopia)

Question 9

pupil

Answer 9

opening where light enters the eye

Question 10

iris

Answer 10

colored portion of eye

Question 11

sclera

Answer 11

white of eye
-attachment of extra ocular muscles

Question 12

cornea

Answer 12

external surface of eye
eye refraction

Question 13

conjunctiva

Answer 13

membrane that folds back from the inside of the eyelid and attaches to the sclera

immune response

Question 14

where does the optic nerve receive visual information from?

Answer 14

retina

Question 15

three laters of the eye from outside to inside

Answer 15

sclera/cornea
choroid/ciliary body
retina

Question 16

phototransduction

Answer 16

conversion of light into electrical signals
-occurs in the retina

Question 17

lens

Answer 17

lens focuses light onto fovea

forms sharp images of near objects

accommodation: changing of shape of lensf

Question 18

fovea

Answer 18

-has highest visual acuity
-smallest visual field
-seeing clearly in bright light

Question 19

what type of photoreceptor cells does the fovea contain?

Answer 19

cone receptors → color

Question 20

optic disc

Answer 20

blind spot

Question 21

vitreous humor

Answer 21

jelly-like liquid located posteriorly that keeps the shape of the eyeball

Question 22

aqueous humor

Answer 22

jelly-like liquid located anteriorly that moistens the cornea

Question 23

superior oblique

Answer 23

• intorsion: down/in
• depresses eye when adducted

Question 24

inferior oblique

Answer 24

• extorsion: up/in
• elevates eye when adducted

Question 25

photoreceptors

Answer 25

only light sensitive cells in the retina rods: black/white, low light vision, high light sensitivity cones: color, low light sensitivity

Question 26

what type of potentials do photoreceptors have?

Answer 26

graded potentials

Question 27

flow of information in the retina

Answer 27

Light→Photoreceptors→Bipolar Cells → Ganglion Cells → Brain (via optic nerve)

Question 28

ganglion cells

Answer 28

only source of output from the retina to the optic nerve

Question 29

what type of potentials do ganglion cells fire?

Answer 29

action potentials

Question 30

pigment epithelium of retina

Answer 30

contains melanin to decrease backscattering of light and prevent blurring of images

Question 31

inner neuronal layer of retina

Answer 31

three neuron chain responsible for phototransduction: -bipolar cells -horizontal cells -amacrine cells

Question 32

interneurons of the retina

Answer 32

horizontal cells amacrine cells

Question 33

superior optic radiation

Answer 33

inferior visual field

Question 34

inferior optic radiation

Answer 34

superior visual field

Question 35

primary visual cortex

Answer 35

discriminates shape, size, texture

Question 36

primary visual cortex "homunculus"

Answer 36

Central vision (fovea): Posterior portion (near the occipital pole) Peripheral vision: Anterior (deeper into the calcarine sulcus) Upper visual field: Below the calcarine sulcus (lingual gyrus) Lower visual field: Above the calcarine sulcus (cuneus gyrus)

Question 37

dorsal/action stream

Answer 37

Pareto-occipital cortex information used to direct movement

Question 38

ventral/perception stream

Answer 38

occipito-temporal cortex information used to recognize visual objects

Question 39

visual versus retinal field

Answer 39

Visual field The external space you see (left/right) Retinal field The internal surface of the retina that receives the light

Question 40

how do retinal fields work

Answer 40

visual image is **inverted and reversed** when projected onto retina ex: - inferior retina sees superior visual field -nasal retina sees temporal visual field

Question 41

2 functional categories of eye movement

Answer 41

stabilize gaze: VOR and optokinetic reflex directing gaze: saccades/smooth pursuit

Question 42

VOR

Answer 42

keeps image of object at same place on retina

Question 43

optokinetic reflex

Answer 43

use of visual info to stabilize images during slow head movements - train example

Question 44

saccades

Answer 44

ballistic, rapid eye movements - reading

Question 45

smooth pursuit

Answer 45

slower tracking movement of eyes -keep moving object on retina

Question 46

conjugate eye movements

Answer 46

both eyes move in same direction

Question 47

vergence eye movements

Answer 47

convergence: both eyes move **towards** midline when target moves from far to near divergence: both eyes move **away** from midline to shift gaze to distant object

Question 48

gaze centers in the reticular formation

Answer 48

paramedian p**on**tine: horiz**on**tal gaze center rostral interstitial nucleus: vertical gaze center

Question 49

medial longitudinal fasciculus

Answer 49

synchronizes eye movements by coordinating activations of gaze centers

Question 50

forebrain control of eye movements

Answer 50

initiating and accurately shifting eyes toward targets

Question 51

frontal eye field

Answer 51

**contralateral** saccades and smooth pursuit

Question 52

Parieto-occipital-temporal cortex

Answer 52

**ipsilateral** smooth pursuit

Question 53

superior colliculus (optic tectum)

Answer 53

accuracy, frequency, and velocity of saccades