Pupillary light reflex pathway:
First neurons (sensory) connects each retina
with both pretectal nuclei in the midbrain at the level of the superior colliculi.
Second neurons (internuncial) connects each pretectal nucleus to both Edinger-Westphal nuclei.
Third neurons (preganglionic motor) connects the Edinger-Westphal nucleus to the ciliary ganglion.
Fourth neurons (postganglionic motor) leaves the ciliary ganglion and passes in the short ciliary nerves to innervate the sphincter pupillae.