optic nerve anatomy

brain anatomy optic cranial nerve human vector diagram nervous system illustration neurology head organ cortex hypothalamus sensory motor olfactory cerebellum cerebral cerebrum section oculomotor trigeminal facial vestibulocochlear glossopharyngeal vagus accessory hypoglossal brainstem eye eyeball ocular vision view retina disc cornea iris bulb 3d visual tract parasympathetic pupil branch biology communication