Which nerve is responsible for the gagging reflex?

The glossopharyngeal nerve is responsible for the gagging reflex because it is involved in the sensory innervation of the oropharynx and the posterior one-third of the tongue. This nerve transmits sensations from these areas to the brain, triggering the reflex that protects the airway by preventing foreign objects from entering the throat. When the oropharyngeal area is stimulated, the glossopharyngeal nerve sends signals to the brain, which in turn initiates the gag reflex through motor pathways, primarily involving the vagus nerve.

While the trigeminal nerve provides sensation in the face and controls muscles of mastication, it does not play a primary role in the gag reflex. The facial nerve is primarily involved in facial expressions and taste sensations from the anterior two-thirds of the tongue, and the recurrent laryngeal nerve mainly controls muscles of the larynx. Thus, the glossopharyngeal nerve is specifically implicated in the gagging response due to its direct role in conveying sensory information from the relevant areas.