The "optic nerve", enters the cranial cavity from the eye and ends in the optic nerve cross on the outside of the floor of the 3rd ventricle , i.e. under the hypothalamus. The optic nerve is not an "ordinary" peripheral nerve but a conduction pathway belonging to the midbrain.
An optic nerve consists of about 1 million thin myelinated axons. These start from the ganglionic cells of the retina and, after passing through the optic nerve cross and the visual pathway (tractus opticus), end mostly in the outer/lateral knee body and to a lesser extent in the upper quadriculus (colliculus superior) and its immediate surroundings. In addition, some threads end in the posterior pole of the thalamus (pulvinar)