Optic Chiasm

Last updated: Jul 31st, 2024

The optic chiasm or optic chiasma is an X-shaped space just in front of the pituitary gland where optic nerve fibers pass through to the brain. The fibers from the nasal half of each retina cross over, but those from the temporal sides do not. Specifically, fibers from the nasal half of the left eye and the temporal half of the right eye form the right optic tract; and the fibers from the nasal half of the right eye and the temporal half of the left form the left optic tract. The nerve fibers then continue in the optic tracts.