Optic radiation


The optic radiation are axons from the neurons in the lateral geniculate nucleus to the primary visual cortex. The optic radiation receives blood through
deep branches of the middle cerebral artery and posterior cerebral artery.
They carry visual information through two divisions to the visual cortex along the calcarine fissure. There is one such tract on each side of the brain. If a lesion only exists in one optic radiation, the consequence is called quadrantanopia, which implies that only the respective superior or inferior quadrant of the visual field is affected.

Structure

The upper division:
The lower division:

Parts

A distinctive feature of the optic radiations is that they split into two parts on each side:
'. The areas of the visual field lost in each eye are shown as black areas. This visual field defect is characteristic of damage to Meyer's loop'' on the left side of the brain.

Function

The optic radiation contains tracts which transmit visual information from the retina of the eye to the visual cortex. Lesions of the optic radiations are usually unilateral and commonly vascular in origin. Field defects therefore develop abruptly, in contrast to the slow progression of defects associated with tumors.

Clinical significance

Examination

Tracts contained within the optic radiation are examined as part of a cranial nerve examination.