Optic nerve (English)

The visual pathway begins with light entering the ocular bulb from the visual fields and being processed by the retina. Visual information is then passed on from the retina by the optic nerve (CN II) through the optic canal (not shown) to the optic chiasm in the middle cranial fossa. From the optic chiasm, the axons of the optic nerve continue posteriorly as the optic tract, which then synapse at the lateral geniculate nucleus of the thalamus. Axons from the lateral geniculate nucleus travel via the optic radiation to finally reach the primary visual cortex. It is important to note that about 90% of the retinal axons synapse directly at the lateral geniculate nucleus. The remaining 10% project to other subcortical nuclei, mainly the superior colliculus. The superior colliculus is involved in visual reflexes, such as saccadic eye movements or tracking of objects in the visual field. The superior colliculus projects onto the pulvinar of thalamus, which in turn projects onto the secondary visual cortex.