The pharyngeal reflex (r. pharyngeus) is an unconditioned reflex that causes contraction of the pharyngeal muscles and elevation of the pharynx when the posterior wall of the pharynx is irritated. This reflex protects the airways from solid food and liquids.
When food or liquid enters the back wall of the pharynx, receptors are irritated, which travels through afferent nerve fibers to the medulla oblongata. Then the impulse along the efferent nerve fibers is sent to the pharyngeal muscles, causing their reflex contraction. The muscles lift the pharynx, closing the entrance to the airways.
Thus, the pharyngeal reflex prevents aspiration and ensures safe swallowing of food, directing it into the esophagus and not into the trachea or bronchi. This protective mechanism is essential for maintaining normal breathing and preventing choking when eating and drinking.