The gag reflex involves sensory input via which nerve and motor output via which nerve?

The gag reflex involves sensory input via which nerve and motor output via which nerve?

• A. Glossopharyngeal (IX) sensory, Vagus (X) motor
• B. Vagus sensory, IX motor
• C. Trigeminal sensory, Facial motor
• D. Glossopharyngeal sensory, Hypoglossal motor

Answer: (A)

The gag reflex uses separate nerves for sensing and moving. Sensory input comes from the oropharynx via the glossopharyngeal nerve (IX), which carries signals from the posterior third of the tongue and the oropharyngeal area to the brainstem. The motor output travels through the vagus nerve (X), with signals arising from the nucleus ambiguus to innervate the pharyngeal muscles (and related soft palate muscles) to produce the gag. This organization explains why IX handles sensation and X handles the motor response. Other nerves don’t provide both the sensing in the oropharynx or the main pharyngeal motor output, so they aren’t correct.

The gag reflex uses separate nerves for sensing and moving. Sensory input comes from the oropharynx via the glossopharyngeal nerve (IX), which carries signals from the posterior third of the tongue and the oropharyngeal area to the brainstem. The motor output travels through the vagus nerve (X), with signals arising from the nucleus ambiguus to innervate the pharyngeal muscles (and related soft palate muscles) to produce the gag. This organization explains why IX handles sensation and X handles the motor response. Other nerves don’t provide both the sensing in the oropharynx or the main pharyngeal motor output, so they aren’t correct.