Optic tract

Tractus opticus

NervousNervesHeadLeft and right

View left in 3D View right in 3D

What it is
The band of visual fibres running back from the chiasm around the cerebral peduncle to the lateral geniculate body of the thalamus, with a small branch to the midbrain for pupil reflexes.
Function
Delivers the opposite half of the visual field of both eyes to the thalamus, which relays it to the visual cortex.
Size
About 3 cm long, 3-4 mm wide
Clinical note
Damage to one tract causes loss of the same half of the visual field in both eyes (homonymous hemianopia), the opposite side to the lesion.

Part of Optic chiasm

Nearby nervous structures Arachnoid mater, Cerebral aqueduct, Hippocampus, Hypothalamus, Midbrain, Oculomotor nerve root (CN III), Optic tract root (CN II), Thalamus, Trochlear nerve (CN IV), Vestibulocochlear nerve (CN VIII)