visual pathway Flashcards Preview

neuro > visual pathway > Flashcards

Flashcards in visual pathway Deck (16)
Loading flashcards...
1

what is the optic nerve developed from?

optic vesicle (an outpocketing of the forebrain)

2

what does the optic nerve do?

transmission of special sensory unfo from retina of eye to primary visual cortex

3

what can the anatomical course of optic nerve be divided into?

- extracranial
- intracranial

4

describe the extracranial portion of the optic nerve

- nerve formed by convergence of axons from retinal ganglion cells
- these cells in turn receive info from photoreceptors of eye
- after formation, nerve leaves through optic canal
- runs along surface of middle cranial fossa

5

describe the start of the intracranial (the visual pathway)

- optic nerves from each eye unite to form optic chiasm

6

what happens at the chiasm?

fibres from nasal (medial) half of each retina cross over to contralateral optic tract
fibres from temprial (lateral) halves remain ipsilateral

7

due to this, what does the left optic tract contain?

contains fibres from left temporal retina and right nasal retina

8

what does the right optic tract contain?

fibres from R temporal retina and R nasal retina

9

where does each optic tract then travel?

travels to its corresponding cerebral hemisphere to reach LGN

10

what is the LGN?

relay system in thalamus
fibres synpase here

11

axons from the LGN then carry visual information via which pathway?

optic radiation

12

what can the optic radiation pathway be divided into?

- upper optic radiation
- lower optic radiation

13

what does the upper optic radiation carry?

- carries fibres from superior retinal quadrants (corresponding to inferior visual field quadrants)
- travels through parietal lobe to reach visual cortex

14

what does the lower optic radiation carry?

- carriers fibres from inferior retinal quadrants (corresponding to superior visual field quadrants)
- travels through temporal lobe via Meyers loop to reach visual cortex

15

why does a pituitary adenoma affect vision?

gland lies close to optic chiasm
enlargement of pituitary gland can affect functioning of optic nerve

16

what does compression of the optic chiasm particularly affect?

fibres that are crossing over from nasal half of each retina
causes bitemporal hemianopia