Vision. Testing Vision. Flashcards
The menace response tests what cranial nerves?
Cranial nerves 2 and 7.
What do we expect to see when we test when we test the pupillary light reflex?
We expect the eye to close almost as soon as light enters the eye.
How does information travel from the eye during the pupillary light reflex?
Some of the fibres branch off the optic tract at the pretectum of the mesencephalon.
These fibres activate parasympathetic nerves of CN-3.
This causes the muscles of the iris to constrict.
If we shine light into 1 eye, will only that eye undergo pupil constriction?
The pupils in both eyes will constrict.
Why do the eyes of both pupils constrict when we shine light into 1 eye?
Because of the crossing over of the fibres from peripheral vision.
When will the left direct PLR occur?
When you shine light into the left eye and the pupil constricts.
When will the left indirect PLR occur?
When you shine light into the left eye and the right eye constricts.
Will crossing over occur in the pretectum during the PLR?
Yes, as the nerve fibres branch off the optic tract to travel to cranial nerve 3.
Does the PLR require the animal to be conscious in order to function?
No as this is a reflex.
What do we assume is damaged if the PLR is not working?
Damage to the brainstem or the animal is dead.
What parts of the eye maybe damaged if the PLR does not work?
Damage to the retina, optic tract, optic chiasm or the optic nerve.
Lesions in what 4 areas will lead to deficits in the PLR and in vision?
Lesions in the retina, optic nerve, optic tract and optic chiasm.
Lesions in what 3 areas will lead to deficits in vision?
Lesions in the lateral geniculate nucleus, the optic striations and the visual cortex.
Lesions in what 3 areas will lead to deficits in the PLR?
The nucleus of cranial nerve 3, the body of cranial nerve 3 and the ciliary ganglion.
What is the parietal eye?
A 3rd eye that is found in reptiles and some fish etc.
