The efferent limb of the gag reflex is mediated by which nerve?

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The gag reflex has two limbs: a sensory (afferent) limb carried by the glossopharyngeal nerve and a motor (efferent) limb that drives the pharyngeal and soft palate muscles. The efferent limb is mediated by the vagus nerve because CN X supplies the motor innervation to most pharyngeal muscles and muscles of the soft palate via the pharyngeal plexus, causing the pharynx to contract and the soft palate to elevate during the reflex. The other nerves listed aren’t responsible for this motor response: the glossopharyngeal nerve provides sensation, while the accessory and hypoglossal nerves govern neck and tongue muscles, not the pharyngeal constrictors involved in the gag reflex. There is a minor motor contribution from glossopharyngeal to stylopharyngeus, but the main efferent pathway for this reflex is the vagus.