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Anatomy term 2 > Visual pathways > Flashcards

Flashcards in Visual pathways Deck (49):
1

What are the reflex pathways in the eye? (2)

1. pupillary light reflex
2. accommodation reflex

2

NOTE

be able to label a diagram of the eye

3

What are the 2 layers of the retina? (2)

1. non-neuronal - pigmented
2. neuronal - photoreceptors

4

NOTE - know the components of the retina

1. optic nerve
2. secondary ganglion cells
3. primary bipolar cells - link photoreceptors to G.cells
4. photo receptors
5. pigmented epithelium
6. interneuron - horizontal
7. interneuron - amacrine

5

What does the amacrine interneurone do in the retina?

modulates ganglion cells activity

6

What does a horizontal interneuron do in the retina?

modulates transmission

7

Why does light have to pass through an array of cells before it reaches the retina?

to help reduce the intensity of the light passing towards the retina

8

Where does the visual pathway run from?

retina to cortex

9

How many neurons are in the chain in the visual pathway?

3

like all the others

10

What are the primary and secondary neurons in the retina outgrowths of?

outgrowth of the diencephalon

11

What cells are in the retina in a visual pathway?

1. photoreceptor
2. bipolar cells
3. ganglion cells

12

Where do the axons of the ganglion cells run over and where to?

run over - retina

to - optic disk/blind spot

13

What does the secondary ganglion cells form?

optic nerve

14

Where does the optic nerve travel to in the visual pathway?

to lateral geniculate nucleus (LGN) in thalamus

then via optic radiation to primary visual cortex (occipital lobe)

15

What cranial nerve number is the optic nerve?

CN II

16

What is the optic nerve an outgrowth of and hence what nervous system is it a part of and what surrounds it?

diencephalon

CNS

surrounded by meninges which goes up to the eyeball

17

What is the blood supply to the eye?

central retinal artery and vein

18

What is papilloedema?

rise in CSF pressure

19

Which foramen does the optic nerve pass through?

optic canal

20

What does the optic nerve take with it and what does it form in the eyeball?

takes a layer of dura

forms the sclera

21

What is the CNS an extension of which meninges?

extension of pia mater

22

What are the symptoms of papilloedema? (4)

1. headaches
2. drowsiness
3. blurred vision
4. vomitting

23

What does the increase pressure in papilloedema compress and what does this prevent and cause?

compress - central retinal vein

prevents - venous drainage from the eye

cause - swelling of the optic disk

24

NOTE - learn the components of the visual pathway - retina to cortex (7)

1. optic nerve
2. retina
3. optic chiasma
4. lateral geniculate nucleus of the thalamus
5. optic radiation
6. primary visual cortex
7. optic tract

25

NOTE- know the cerebral topography

Lateral aspect of brain

1. visual cortex
2. visual association

Medial aspect of the brain

1. calcarine sulcus
2. visual association

26

Where does the striate cortex lie in relation to the calcimine sulcus?

1. above and below the calcarine sulcus

27

Does the nasal part of the retina send information contra laterally or ipsilaterally?

contralaterally

28

Does the temporal part of the retina send information contra laterally or ipsilaterally?

ipsilaterally

29

Where does information from the nasal part and the temporal part first get sent to?

LGN - lateral geniculate nucleus

30

NOTE

draw out visual pathway

31

Where does the left half of the visual field go?

right hemisphere

32

Where does the right half of the visual field go?

left hemisphere

33

Where does the upper visual field go?

lower bank of the calcarine sulcus

34

Where does the lower visual field go?

upper bank of the calcarine sulcus

35

Where does the centre of visual axis (macula) go to?

occipital pole

36

In terms of optic radiation, how do fibres of the LGN pass to the upper and lower banks of the calcimine sulcus and what can this allow - give an example?

via different pathways

allows prediction of deficits of vision

e.g. Meyers loop

37

What is scotoma?

localised patch of blindness

38

What is anopia?

refers to the loss of one or more quadrants of the visual field

39

What is hemianopia?

half of the visual field is lost

40

What is quadrantanopia?

quarter of the visual field is lost

41

What is homonymous?

visual field losses are similar for both sides

42

What does it mean by heteronymous?

visual field losses are different sides

43

Do all optic tracts go to the LGN?

no - 10% take a medial root to the pre-tactal area - midbrain

44

What is the pupillary light reflex?

ability of both pupils to respond (constrict or dilate) dependent on the level of light the retina receives

45

What 2 cranial nerves does the pupillary light reflex use and star whether they are afferent or efferent?

1. optic nerve - afferent root
2. oculomotor nerve - efferent root

46

What are the 2 components of the pupillary light reflex?

1. direct component - light in on eye and the same pupil constricts

2. consensual component - light in one eye other pupil constricts

47

What nucleus does the pupillary light reflex concern?

Edinger- Westphal nucleus

48

NOTE

understand the pupillary light reflex

49

NOTE

understand visual defects