Which cranial nerve provides both afferent and efferent limbs of the cough reflex?

Which cranial nerve provides both afferent and efferent limbs of the cough reflex?

• A. CN X
• B. CN IX
• C. CN V
• D. CN XII

Answer: (A)

The same nerve handles both sensing and signaling in the cough reflex. Sensory information from the larynx and lower airway is carried by the internal branch of the superior laryngeal nerve, a branch of the vagus, to the medullary cough center. In response, motor output returns via the vagus to the laryngeal muscles (through the recurrent laryngeal branches) to close the glottis and generate a forceful expiration, with the expiratory effort assisted by other muscles controlled by spinal nerves. This dual role—afferent sensing and efferent motor control—is why this nerve is the correct choice. Other nerves don’t provide both limbs of the reflex; they contribute to other sensory or motor functions.

The same nerve handles both sensing and signaling in the cough reflex. Sensory information from the larynx and lower airway is carried by the internal branch of the superior laryngeal nerve, a branch of the vagus, to the medullary cough center. In response, motor output returns via the vagus to the laryngeal muscles (through the recurrent laryngeal branches) to close the glottis and generate a forceful expiration, with the expiratory effort assisted by other muscles controlled by spinal nerves. This dual role—afferent sensing and efferent motor control—is why this nerve is the correct choice. Other nerves don’t provide both limbs of the reflex; they contribute to other sensory or motor functions.