The pharyngeal reflex, also known as the gag reflex, prevents unintentional foreign objects from entering the pharynx. However, studies show the role of the gag reflex and airway protection from aspiration is unclear at this time.
Stimulus of the posterior tongue, soft palate, or posterior pharyngeal wall → sensory afferent nerve mainly via CN 9 glossopharyngeal nerve, although can have some contribution from CN 10 internal branch of superior laryngeal nerve → brainstem → motor efferent nerve mainly via CN 10 → causes bilateral pharyngeal muscle contraction.
1. Bassi GS, Humphris GM, Longman LP. The etiology and management of gagging: a review of the literature. J Prosthet Dent. 2004 May;91(5):459-67.