Vision (for eye antomy see eye and ear deck in anatomy)

Question 1

what is accomodation

Answer 1

adjustment of the lens in the eye so clear images of objects at different distances are formed on the retina

Question 2

what refracts light entering the eye

Answer 2

cornea (2/3)

lens (1/3)

Question 3

where is light focused onto

Answer 3

retin

Question 4

what regulates the shape of the lens

Answer 4

ciliary muscles

Question 5

what does sympathetic stimulation of the ciliary muscles do

Answer 5

relaxes them

flattened and weak lens - less light bending

Question 6

what does parasympathetic stimulation of the ciliary muscles do

Answer 6

contracts ciliary muscles
accomodation
rounded, strong lens - more light bending

Question 7

what makes up the wall of the eyeball

Answer 7

fibrous sclera and cornea
choroid, iris and ciliary body (uvea)
retina (rods and cones)

Question 8

what are the 2 cavities of the eye

Answer 8

anterior and posterior

Question 9

describe the posterior cavity

Answer 9

separated from anterior cavity by the lens

filled with vitreous humour

Question 10

what separates the anterior and posterior cavity

Answer 10

lens

Question 11

describe the anterior cavity

Answer 11

separated from posterior cavity by the lens
divided into anterior and posterior CHAMBER by the iris
contains aqueous humour

Question 12

what controls the size of the pupil

Answer 12

iris

Question 13

what are the 2 muscles associated with the iris

Answer 13

sphincter and dilator

Question 14

what does parasympathetic stimulation if the iris do

Answer 14

pupillary constriction

sphincter contraction

Question 15

what does sympathetic stimulation of the iris do

Answer 15

pupillary dilation

dilator constriction

Question 16

where is the ocular blood supply from

Answer 16

ophthalmic artery (from internal carotid)
branches - most impoatant is central retina artery (supplies retina)

Question 17

where is the primary visual cortex

Answer 17

occipital lobe calcarine sulcus

Question 18

what is the function of the visual association cortex

Answer 18

interpreting visual images, recognition, depth perception, colour vision

Question 19

where is the visual association cortex

Answer 19

surrounds primary visual cortex (in calcarine sulcus)

Question 20

describe light transmission from temporal visual field

Answer 20

• temporal visual field goes to nasal portion of retina
• optic nerve carries axons of cells in ganglionic layer of retina
• leave orbit via optic canal and enter cranial cavity
• nasal portion fibres cross at optic chiasm
• optic tracts carry fibres posteriolaterally around cerebral peduncles
• terminate at lateral geniculate body of thalamus

Question 21

describe Baum’s loop

Answer 21

parietal lobe
superior loop
carries fibres from INFERIOR visual field (so superior part of retina)

Question 22

describe Meyer’s loop

Answer 22

Temporal lobe
lateral loop
carries fibres from SUPERIOR visual field (so inferior portion of retina)

Question 23

what would cause a left homonymous hemianopia

Answer 23

defect in left optic nerve

Question 24

what would cause a bitemporal hemianopic

Answer 24

problem in optic chiasm

Question 25

which fibres cross at the optic chiasm

Answer 25

from temporal visual field = nasal part of retina

Question 26

what would cause a left nasal and right temporal hemianopia

Answer 26

problem in left optic tract

Question 27

what would cause a right upper /(contralateral) homonymous superior quadrantanopia

Answer 27

problem in left Meyer's loop (temporal lobe, lateral loop)

Question 28

what would cause a right lower/ contralateral homonymous inferior quadrantanopia

Answer 28

problem in left Braun's loop (parietal lobe, superior loop)

Question 29

what would cause a left nasal and right temporal hemianopia with macula sparing

Answer 29

problem in optic radiation