The eye Ch 52

Question 2

Visual pathway

Answer 2

Nasal halves:
Optic nerves –>cross at optic chiasm–>optic tract

Temporal retinas: Optic nerve–>optic chiasm (don’t cross)–>optic tract

Question 3

Fibers of optic tract synapse in

Answer 3

dorsal lateral geniculate nucleus (thalmus)

Question 4

Visual fibers pass to (4)

Answer 4

1. suprachiasmatic nucleus of hypothalmus
2. Pretectal nuclei in midbrain
3. Superior colliculus
4. Ventral lateral geniculate nucleus of thalmus

Question 5

Suprachiasmatic nuclus of hypothalmus responsible for

Answer 5

circadian rhythms

Question 6

Pretectal nuclei in midbrain responsible for

Answer 6

reflex movement of eye

Question 7

Superior colliculus responsible for

Answer 7

eye movement

Question 8

Ventral lateral geniculate nucleus of thalamus responsible for

Answer 8

body behavior

Question 9

Layers of dorsal lateral geniculate nucleus

Answer 9

half come from one eye, half from the other

Question 10

dorsal lateral geniculate nucleus role

Answer 10

gate transmission of signals, controls how much of signal passes to cortex

Question 11

Magnocellular layers input comes from

Answer 11

type M ganglion cells

(rapid conduction, black and white)

Lizard brain

Question 12

Parvocellular layers get input from

Answer 12

type P ganglion cells

(transmit color, convey accuracy, moderate conduction velocity)

Question 13

Visual cortex location

Answer 13

calcarine fissure area, terminus of visual signals

Question 14

Primary visual cortex has ___ layers

Answer 14

6 layers

Question 15

M retinal ganglion cells terminate

Answer 15

in Ivcalpha

Question 16

P ganglion cells terminate in

Answer 16

layer Iva and Ivcbeta

Question 17

color blobs role

Answer 17

activated by color signals, thought to decipher color

Question 18

Two pathways for analysis of visual information

Answer 18

1. 3-D position, gross forms and motion of objects
2. Analysis of visual detail and color

Question 19

Perimetry

Answer 19

measures blindess in portions of the retina

Question 20

Scotomata

Answer 20

blind spots outside of optic disk

Question 21

Retinitis pigmentosa

Answer 21

portions of retina degenerate and lead to excessive melanin deposits

Question 22

Lesion on optic nerve yields

Answer 22

blindness

Question 23

lesion bitemporal hemainopsia

Answer 23

interruption of optic chiasm prevents crossing of impulses = half blindess

Question 24

Lesion homonyous hemianpsia

Answer 24

interruption of an optic tract results in the loss of nervet in the corressponding half of retina

same side lesion, niether eye can see objects to opposite side of head

Question 25

Neural pathway for vision

Answer 25

CN III
CN IV
CN VI

Question 25

How many eye muscles are there

Answer 25

3 pairs (6 total)

Question 26

Voluntary fixation movements

Answer 26

person chooses to find object to focus on

Question 27

involuntary fixation movements

Answer 27

holds eye firmly once it has been found

Question 28

Three types of eye movements

Answer 28

1. Flicking
2. Slow drift
3. continuous tremor

Question 29

Saccadic movement of eye

Answer 29

continually moving visual scene - eye fixes on one object after another

i.e. reading, driving

Question 30

Pursuit movement

Answer 30

Eyes remain fixed on moving object

Question 31

Superior colliculi role

Answer 31

turning towards a visual disturbance

(also involves somatic and acoustic signals)

Question 32

Fusion of the visual image

Answer 32

if two images are not “in register” interference excitation signals oculomotor apparatus

Question 33

Stereopsis

Answer 33

Detects distances of visual objects up to 200 feet

Question 34

Depth perception is determined by

Answer 34

pathways activated - different ones register based on how far away object of focus is

Question 35

Strabismus

Answer 35

squint or cross eye, lack of fusion in one or more visual coordinates

fix: patch or surgery

Question 36

Accommodation clues - what triggers them?

Answer 36

changing distance of focus leads to clues for accomodation

Question 37

Accommodation - what else helps accomodation?

Answer 37

Pupillary diameter

Question 38

changing distance leads to the following clues for accomodation:

Answer 38

1. Chromatic abberration - the eye can determine which color ray is better in focus
2. convergence
3. Clarity of focus in depth of fovea vs edges
4. Degree of accommodation oscillates - visual image becomes clearer when oscillation of lens strength changes in proper direction

Question 39

Horners syndrome:

Answer 39

interruption of sympathetic nerve fibers to pupillary dilator muscle

pupil remains constricted in one ye and eyelid droops, blood vessels remain dilated