Individual Readiness Assurance Test (iRAT) 4 Head And Neck Practice Test

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

Vagus nerve (CN X) Glossopharyngeal nerve (CN IX) Facial nerve (CN VII) Hypoglossal nerve (CN XII)

Correct Answer:

Glossopharyngeal nerve (CN IX)

Explanation:

The afferent limb of the gag reflex is carried by the glossopharyngeal nerve. Sensory information from the oropharynx, including the posterior one-third of the tongue and surrounding pharyngeal areas, travels via CN IX to the brainstem, where it is processed and triggers the protective motor response. The motor part of the gag reflex is carried out by the vagus nerve, which acts on the pharyngeal muscles to produce the gag. So CN IX provides the sensory input that starts the reflex, while CN X handles the efferent output. The facial nerve supplies taste from the anterior two-thirds of the tongue and facial expression, and the hypoglossal nerve controls tongue movements—neither carries the afferent gag signal.

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