In this tutorial, we will learn the neuroanatomy of the pupillary light reflex. Key structures/terms: eyes, lenses, red nuclei, superior colliculi, midbrain, diencephalon, midbrain-diencephalic junction; pretectal olivary nucleus of the pretectal area, which lies anterolateral to the superior pole of the superior colliculus; the posterior commissure, which forms the roof of the cerebral aqueduct (of Sylvius); the paired Edinger-Westphal nuclei of the oculomotor complex; the bilateral ciliary ganglia in the posterior orbit; parasympathetic-innervated sphincter pupillae muscle fibers, sympathetic-innervated pupillary dilator muscle fibers, retinae, optic nerve, optic tract, lateral geniculate nucleus, ciliary muscle of the ciliary body.