In the pupillary light reflex, the efferent limb travels from which nucleus through which nerve to reach the sphincter pupillae?
- A Superior salivatory nucleus via the facial nerve
- B Edinger-Westphal nucleus via the oculomotor nerve ✓
- C Accessory ciliary ganglion via the trochlear nerve
- D Solitary tract nucleus via the trigeminal nerve
Correct answer: B. Edinger-Westphal nucleus via the oculomotor nerve
Explanation
Light information reaches the pretectal area, projects bilaterally to the Edinger-Westphal nuclei, and preganglionic parasympathetic fibres leave in the oculomotor nerve, synapse in the ciliary ganglion, and reach the sphincter pupillae via short ciliary nerves. The superior salivatory nucleus drives lacrimation via the facial nerve, and the solitary nucleus receives visceral afferents, neither of which participates in the light reflex.
Reference: Gray's Anatomy for Students, 4th ed.
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