Visual Pathway

Question 1

What is the visual field?

Answer 1

Everything you see with one eye (including the periphery)

Question 2

What is the fovea of the eye?

Answer 2

Tiny pit located in the retina that provides the clearest vision

Question 3

What kind of tests looks at the visual field?

Answer 3

Confrontation test or automated perimetry, not to be confued with visual acuity testing

Question 4

How do images of objects in our visual field compared to how we actually interpretate them?

Answer 4

They are upside down and inverted (left and right), so the right visual cortex ees the left half of the visual field and vice versa

Question 5

Explain the process of the visual pathway?

Answer 5

1) All fibres from the eye pass through the optic nerve to the optic chiasma
2) At the optic chiasma the medial nasal fibres cross to the opposite side
3) So the optic tract contains fibres from the lateral temporal half of the ipsilateral eye and the crossed over nasal fibres from the contralateral eye
4) This corresponds to all fibres from the opposite half of the visual field
5) Fibres from optic tract synapses at the LGB of the thalamus
6) From here the optic radiation passes behind the internap capsule (retro-lentiform fibres) to reach the primary visual cortex in the occipital lobe (area 17)
7) Thus the right visual cortex sees the left half of the visual field and vice versa

Question 6

What does LGB stand for?

Answer 6

Laterl geniculate body

Question 7

What fibres cross to the opposite side at the optic chiasma?

Answer 7

Nasal fibres

Question 8

What fibres does the optic tract contain?

Answer 8

Fibres from the lateral temoral half of the ipsilateral eye and the crosed over nasal fibres from the contralateral eye

Question 9

label the visual pathway?

Answer 9

Question 10

In what lobe is the primary visual cortex located?

Answer 10

Occipital lobe

Question 11

In what area of the brain is the primary visual cortex located?

Answer 11

Area 17

Question 12

What is the general rule of thumb for where a lesion is in relation to the side of loss of vision?

Answer 12

Is usually in the opposite side from visual loss, but this is not always the cases such as with optic nerve damage

Question 13

what happens with a lesion in the right optic nerve?

Answer 13

blindness in one eye

Question 14

What happens with a lesion in the optic chiasma disrupted in the middle?

Answer 14

Bitemporal hemianopia

Question 15

What is bitemporal hemianopia?

Answer 15

Vision missing in lateral temporal half of visual field

Question 16

What happens with a lesion in the right optic tract?

Answer 16

Homonymous hemianopia (can see one half of each eye, in this case the lateral half of the left eye and the medial half of the right eye)

Question 17

What happens when optic radiation is damaged (occipital damage)?

Answer 17

Contralateral homonymous hemianopia

Question 18

label the different pathway damages?

Answer 18

Question 19

how do you illicit the pupillary reflex?

Answer 19

Question 20

what is the pathway of light reflex in the afferent limb?

Answer 20

Question 21

what is the pathway of light reflex in the efferent limb?

Answer 21