Which cranial nerve is associated with the third pharyngeal arch?

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

Answer: (C)

Think of pharyngeal arches as developmental modules each tied to a specific cranial nerve that both supplies the muscles formed from that arch and carries sensory input from the arch’s region. The third arch is connected to the glossopharyngeal nerve because this nerve provides motor innervation to stylopharyngeus, a muscle derived from the third arch, and carries sensory fibers from the oropharynx and the posterior one-third of the tongue. That link is why the third arch is associated with the glossopharyngeal nerve. In contrast, the first arch maps to the trigeminal nerve, the second to the facial nerve, and the fourth through sixth arches to branches of the vagus nerve, which is why those nerves align with the other arches.