| a site at the base of the forebrain where the inner half of the fibers of the left and right optic nerves cross to the opposite side of the brain. |
| optic chiasma n. A structure in the brain formed by the partial intersection or crossing of the optic nerve fibers on the underside of the hypothalamus. Also called optic chiasm. |
optic chiasm n.
A flattened quadrangular body that is the point of crossing of the fibers of the optic nerves. Also called optic decussation.