Topic 10 Visual Pathway Flashcards
What are the 8 structures of the visual pathway?
- Temporal retina
- Nasal retina
- Optic nerve
- Optic chiasma
- Optic tract
- Lateral geniculate body
- Optic radiations (Meyer’s loop and baum’s loop)
- Primary visual cortex
What is the relationship between the nerve fibres and visual field?
Visual field is always opposite of nerve fibres
e. g right temporal NF corresponds to left nasal VF
* Does not apply to the structures. E.g right optic nerve will still contain R temp and nasal and VFD will be left Uniocular blindness
what are the 5 parts of the optic nerve?
- Intraocular Region
- intraorbital region
- intracanlicular region
- intracranial region
- chiasma
where does the ON fibres exit the eyeball?
lamina cribrosa
what occurs at the optic chiasma?
hemidecussation
The nasal retinal fibres, including those from the nasal half of the macula, cross-over to the contralateral (opposite) optic tract
•The temporal retina fibres DO NOT cross
what are the 2 structures related to the optic chiasma?
- The pituitary gland lies below the optic chiasma
2. The arterial circle of Willis supplies to the chiasmal region and the blood vessels are located around the chiasma
what nerve fibres do the optic tract contain?
- Optic tract carries uncrossed (temporal) & crossed (nasal) fibres.
- Right optic tract carries the temporal fibres from the right eye & nasal fibres from the left eye.
- Left optic tract carries the temporal fibres from the left eye & nasal fibres from the right eye.
what happens at the lateral geniculate nucleus? what NF does it contain?
The ganglion cells of the retina synapse here
Contains the same nerve fibre distribution as the optic tract.
what arethe optic radiations? Hint what does it connect
what NF does it contain?
The axons from the LGN to the visual cortex are the optic radiations.
Contains the same nerve fibre distribution as the optic tract.
what happens at the visual cortex? what NF does it contain?
All projections end in the Primary Visual Cortex (PVC) (striate cortex, Brodmann’s area 17, V1)
Contains the same nerve fibre distribution as the optic tract.
what is the image orientation on retina?
image will be laterally or vertically inverted based on the orientation of the object.
what is visual field?
Visual field is the space in which objects are seen at the same time during steady fixation.
REMB TO REFER TO CLASS NOTES FOR VFD
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What is the blood supply of the visual pathway?
Optic nerve: circle of hallerzinn (formed by short posterior ciliary arteries)
the rest if the structures: circle of Willis (formed by central retinal artery)
