Which nerve supplies the muscles of the 2nd pharyngeal arch?

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

Answer: (B)

Muscles from the second pharyngeal arch are innervated by the facial nerve because each arch is linked to a specific cranial nerve. The second arch gives rise to muscles such as those of facial expression, along with the stapedius, stylohyoid, and the posterior belly of the digastric, all of which receive motor input from the facial nerve. That connection is why this nerve is the correct choice. Other nerves map to different arches: the glossopharyngeal nerve supplies third-arch derivatives like stylopharyngeus, the vagus nerve covers muscles from multiple arches via pharyngeal branches, and the trigeminal nerve innervates first-arch muscles such as those involved in mastication and the anterior digastric. Remembering this arch-to-nerve correspondence helps explain why the facial nerve specifically supplies the muscles of the second arch.