1. Retinal ganglion cell neurons (first-order)
   • Impulses from the retina travel in the afferent optic nerve (CN II) to the optic chiasm
   • At the optic chiasm
     • Fibers from the temporal half of the retina → ipsilateral optic tract → ipsilateral pretectal nucleus in the midbrain
     • Fibers from the nasal half of the retina crossover → contralateral optic tract → contralateral pretectal nucleus
2. Fibers from each pretectal nucleus innervate both the ipsilateral and contralateral Edinger-Westphal nuclei.
3. efferent limb arises from Edinger-Westphal nucleus → oculomotor nerve (CN III) → ciliary ganglion. See Horner syndrome if ciliary ganglion is damaged.
4. ciliary ganglion → short ciliary nerves → iris sphincter muscle → direct and consensual pupillary constriction

Mnemonic

2 priests educated 3 cili (silly) pupils:

• Optic nerve (cranial nerve 2)
• Pretectal nucleus
• Edinger-Westphal nuclei
• Oculomotor nerve (cranial nerve 3)
• Ciliary sphincter → pupillary constriction