Pituitary Tumour Flashcards
Where does the optic nerve begin?
It begins in the ganglion cell layer of the retina.
What is the function of the optic nerve?
It is a sensory (afferent) nerve that transmits visual information from the eye to the brain.
What is the optic chiasm?
The optic chiasm is where the optic nerves from both eyes meet and partially cross.
What fibers cross at the optic chiasm?
The nasal retinal fibers, which carry information from the temporal visual fields, cross to the opposite side.
What fibers do not cross at the optic chiasm?
The temporal retinal fibers, which carry information from the nasal visual fields, do not cross.
After the optic chiasm, what do the fibers form?
They form the optic tracts, which carry information to the lateral geniculate body of the thalamus.
What comes after the lateral geniculate body in the visual pathway?
The optic radiations, which lead to the primary visual cortex in the occipital lobe.
What structure is located near the optic chiasm and can cause visual deficits if it enlarges?
The pituitary gland, located in the sella turcica.
What visual deficit results from compression of the optic chiasm by a pituitary tumor?
Bitemporal hemianopia – loss of the temporal visual fields in both eyes.
Why does a pituitary tumor cause bitemporal hemianopia?
Because it compresses the crossing nasal fibers in the center of the optic chiasm, which carry temporal visual field information.
