The Edinger-Westphal nucleus corresponds to which cranial nerve?

• A. CN III
• B. CN VII
• C. CN IX
• D. CN X

Answer: (A)

This question focuses on which cranial nerve the Edinger-Westphal nucleus belongs to. The Edinger-Westphal nucleus contains preganglionic parasympathetic neurons that regulate pupil constriction and lens focusing. These parasympathetic fibers travel with the oculomotor nerve (cranial nerve III) to the ciliary ganglion, then to the sphincter pupillae and ciliary muscle. So, the Edinger-Westphal nucleus is part of the CN III system.

The other nerves listed have different nuclei and functions. CN VII is the facial nerve with its own parasympathetic origins linked to the lacrimal and salivary glands via the superior and submandibular ganglia, not the Edinger-Westphal nucleus. CN IX and CN X have their own motor and parasympathetic nuclei (such as the nucleus ambiguus and dorsal motor nucleus of X), which are unrelated to the Edinger-Westphal nucleus.