Neuro 12: Visual System

the fibrous layer of the eye contains what 3 things?

cornea, sclera, dura

the dura covers the ____ _____

optic disc

the choroid/vascular layer contains what 3 things?

ciliary body, pupil, iris

the inner layer/retina contains what two types of retina?

secretory retina, visual retina

what produces aqueous humor?

secretory retina

what happens when the ciliary muscles contract?

relaxes the zonular ligaments, lens becomes more spherical, increasing refractive power.

what happens when the ciliary muscles relaxes?

ciliary zones gain tension, flattens disc, for distance vision

what is a direct branch off of the internal carotid artery that supplies blood to the eye?

ophthalmic artery

the anterior chamber is between the ____ and ____

cornea, iris

where is aqueous humor produced?

between the iris and lens, in the posterior chamber

describe the characteristics of presbyopia

“old eyes”, lens loses its elasticity, reduced refractive power, poor near vision

describe the characteristics of hyperopia

far sighted, refractive power is too weak

describe the characteristics of myopia

near sighted, refractive power is too strong

in individuals with myopia the image is focused at a point in ______ of the retina

front

describe the characteristics of astigmatism

cornea surface is misshaped, not a sphere

astigmatism definition:

image of distant and near objects cannot be focused on the retina

hyperopia is corrected with a ____ lens, myopia is corrected with a ____ lens.

convex, concave

glaucoma

increased intraocular pressure restricting blood flow to the retina causing visual loss

glaucoma is treater pharmacological using drugs that cause pupillary _______

constriction

fundus

back of eye

optic disc aka _____

papilla

where is the origin of the optic nerve?

optic disc

are there cones and rods in the optic disc?

no

cones work better in the _____. rods work better in the _____.

light, dark

the fovea lies int eh center of the macula and only contains small _____

cones

what are of the eye has the highest visual acuity?

fovea centralis

papilledema

increase in intracranial pressure, compresses the vein in the optic nerve, inhibiting drainage and causing swelling of the optic disc.

the retina is derived from the _____ _____

neural tube

Retinal pigment epithelium (RPE) absorbs stray ____ and takes on a supportive role

light

neural retina encodes ____, ____, and ____.

color, movement, size

Are there more rods or cones in the neural retina?

rods

T/F: ganglion cells are unmyelinated

True!

neural retina cell layers from closest to lens to furthest away

ganglion cells, bipolar cells, cones+rods

cones _____ resolution, rods _____ resolution

high, low

do rods or cones do color?

cones

a bipolar cell can connect with ____ cone cell leaving a ___ and ___ ____ receptive field.

1, small, color sensitive

a bipolar cell can connect with over ____ rod cells. leaving a ____ and ____ _____ receptive field.

50, large, color insensitive

function of amacrine and horizontal cells

help eyes adjust to see well under both bright and dim light conditions

retinal ganglion cells slowly adapting characteristics

color sensitive, object detectors

retinal ganglion cells, rapidly adapting characteristics

color insensitive, motion detectors

retinal ganglion cells travel to and terminate in the ____ ____ _____ of the thalamus

lateral geniculate nucleus

what causes visual loss in the central visual field, and is the leading cause of blindness in the elderly

Macular degeneration

retinal detachment

neural retina is torn away from retinal pigment

diabetic retinopathy is characterized by _________ in the retina and blindness in the regions affected

microaneurysms

visual acuity depends on _____ and _______

refractory, cytoarchitecture

cytoarchitecture

arrangement of cells

what is the clinical examination of the binocular visual fields

confrontation field test

what kind of color vision do humans have?

trichromatic (red, green and blue)

the visual field center operates best under ____ illumination and provides ____ visual acuity and color sensitivity

high, greatest

the peripheral visual field operates best under ____ illumination, and has ____ color sensitivity and _____ spacial acuity

low, little, poor

binocular fusion provides cues for _____ perception

depth s

strabismus

one eye deviates

lateral geniculate of the thalamus function

visual perception

superior colliculus of the midbrain function

controls eye movements

pretectum of the midbrain fxn

controls pupillary light reflex

suprachiasmatic nucleus of the hypothalamus function

controls circadian rhythm

the optic nerve is myelinated by ________

oligodendrocytes

the medial half of the lateral geniculate body contains _____ information and the lateral half carries ____ information

nasal, temporal

fibers from the LGB enter the _____ ______.

optic radiations

optic radiations are also known as the ______ tracts

geniculocalcarine

area 17 is located in the occipital lobe above and below the ______ ______ on the medial aspect of the hemisphere

calcarine sulcus

area 17: fibers representing the upper retina terminate above the sulcus in the _____. fibers representing the lower retina terminate below the sulcus in the _____ _____.

cuneus, lingual gyrus

the primary visual cortex is known as area ____.

17

what is retinotopic organization

spacial layout of the rent in teh visual association cortex.

Where is the macula represented in the visual cortex?

Most posterior (at the occipital pole).

Where is peripheral retina represented in the visual cortex?

More anterior (deeper compared to the macula)

What are the two visual processing pathways from the association visual cortex?

Dorsal (to parietal lobe) and ventral (to temporal lobe)

What is the function of the dorsal pathway?

Spatial vision, motion, and guiding movement (“where/how”).

draw the lesions bitchhhhhh

you can do this!

3 causes of optic nerve lesion

optic neuritis, trauma, glaucoma

cause of optic chiasm lesion

pituitary tumor

cause of optic tract or both radiations lesion

stroke of middle cerebral artery

cause of both banks of calcimine fissure lesion

Posterior cerebral artery occlusion