Fig. 15 Parasympathetic innervation to the pupillary constrictor fibers originates within the Edinger-Westphal subnucleus (EW) of the oculomotor nucleus (3). Parasympathetic axons enter the orbit as part of the inferior branch of the oculomotor nerve. Synapse occurs in the ciliary ganglion (CG) before finally innervating the pupillary constrictor muscle. (SC, superior colliculus; PTN, pretectal nucleus; LGN, lateral geniculate; OT, optic tract; CHI, chiasm; ON, optic nerve; RET, retina).