The pharyngeal reflex, also known as the gag reflex, is an involuntary response that occurs when the back of the throat is stimulated. This reflex helps protect the airway by preventing choking and aspiration of foreign objects or substances. It is triggered by touching the soft palate, the back of the tongue, or the pharynx. This reflex is mediated by the glossopharyngeal nerve and the vagus nerve, which send signals to the brain to initiate the gagging response. The pharyngeal reflex is commonly tested in medical examinations to assess the function of these nerves and the overall health of the nervous system.