Final answer:
The pupillary light reflex involves the sensory input of the optic nerve and the parasympathetic motor output of the oculomotor nerve. It controls the constriction of the pupil in response to bright light.
Step-by-step explanation:
The pupillary light reflex involves the sensory input of the optic nerve and the parasympathetic motor output of the oculomotor nerve. When light hits the retina, it stimulates specialized photosensitive ganglion cells which send a signal along the optic nerve to the pretectal nucleus in the midbrain. From there, a neuron projects to the Edinger-Westphal nuclei in the oculomotor complex, which give rise to preganglionic parasympathetic fibers that project through the oculomotor nerve to the ciliary ganglion in the posterior orbit. The postganglionic parasympathetic fibers from the ganglion project to the iris and release acetylcholine onto circular fibers that constrict the pupil to reduce the amount of light hitting the retina.