The structure indicated is the optic tract.
The pathway of light from the retina to the occipital cortex is as follows:
- Optic nerve
- Optic chiasm
- Optic tract
- Lateral geniculate body
- Optic radiation
- Occipital cortex
There are two optic tracts, a right and a left optic tract. The optic tract is an extension of the optic nerve, conveying information from the optic chiasm to the lateral geniculate nucleus. The optic tracts convey information from the opposite visual field – the right optic tract will convey information from the left visual field, and vice versa.
The right optic tract conveys visual information of the left nasal retinal fibres and the right temporal retinal fibres. A lesion of the right optic tract will therefore result in a left homonymous hemianopia.
The left optic tract conveys visual information of the right nasal retinal fibres and the left temporal retinal fibres. A lesion of the left optic tract will therefore result in a right homonymous hemianopia.