INBDE (Integrated National Board Dental Examination) Practice Exam

The correct answer is the Glossopharyngeal nerve (IX). The gag reflex is a protective mechanism of the throat that involves the reflex contraction of the muscles of the pharynx. The sensory limb of the gag reflex is mediated by the Glossopharyngeal nerve (IX), specifically the afferent fibers from the pharyngeal plexus. The Glossopharyngeal nerve provides sensory innervation to the back of the throat, the pharynx, the soft palate, and the posterior third of the tongue. Therefore, it is responsible for carrying sensory information related to the gag reflex.