Optic nerve

The optic nerve (II) is a sensory nerve responsible for vision. Anatomically, it is considered a tract of the central nervous system rather than a true peripheral nerve.

Number : II

Sensory, motor, or both : sensory

Origin : retinal ganglion cells, whose axons converge at the optic disc of the retina.

Route / Reports : the axons pass through the cribriform area of the sclera, then enter the cranial cavity through the optic canal of the presphenoid bone. They reach the optic chiasm, located rostral to the hypophysis, where approximately 75% of the fibers cross to the opposite side in the dog.

Distribution : after the optic chiasm, the fibers continue as the optic tracts along the lateral aspects of the diencephalon and terminate in the lateral geniculate nucleus, pretectal region, and rostral colliculus.

Description : The optic nerve is formed by axons of retinal ganglion cells that converge at the optic disc, pass through the sclera and optic canal, and reach the optic chiasm rostral to the hypophysis. In the dog, about 75% of the fibers decussate at the chiasm, and the fibers then continue caudally as the optic tracts toward the lateral geniculate nucleus, pretectal region, and rostral colliculus.