CRANIAL NERVE II: OPTIC NERVE

1. It occurs at the sella turcica, on the body of the sphenoid bone, right at the Pituitary Gland.
2. Fibers from the medial side of each eye cross at the Optic Chiasm, to join the Optic Tract on the opposite side.

i. So medial fibers from the Left Eye will go to the right side of the brain, and medial fibers from the right eye will go to the left side of the brain.

ii. These fibers are carrying peripheral visual information for both respective eyes.

3. Fibers from the lateral side of each eye do not cross at the Optic Chiasm, but instead join the Optic Tract directly on their own side.
4. TUNNEL VISION: Indicates a lesion at the optic chiasm. Medial fibers have been impinged upon, destroying peripheral vision in both eyes.

i. Pituitary Tumor can impinge on the optic chiasm, causing tunnel vision.

OPTIC TRACT: That portion extending between the Optic Chiasm and the Lateral Geniculate Nucleus in the brainstem. This portion of nerve is not properly called the Optic Nerve.

Category: Anatomy Notes