Which cranial nerve controls tongue movement essential for swallowing?

Which cranial nerve controls tongue movement essential for swallowing?

• A. Hypoglossal nerve (CN XII)
• B. Trigeminal nerve (CN V)
• C. Facial nerve (CN VII)
• D. Glossopharyngeal nerve (CN IX)

Answer: (A)

Tongue movement essential for swallowing is controlled by the hypoglossal nerve. This nerve provides motor supply to all intrinsic tongue muscles and to most extrinsic tongue muscles, enabling the tongue to protrude, retract, and precisely shape and push the bolus toward the pharynx during the oral phase of swallowing. When CN XII is intact, the tongue can coordinate these movements smoothly to form a cohesive bolus and propel it posteriorly for swallowing. Understanding the other nerves helps confirm why this is the correct motor control for the tongue. The trigeminal nerve mainly handles muscles of mastication and sensation to the face, with only limited, indirect influence on tongue sensation, not the primary tongue muscles required for swallowing. The facial nerve primarily controls facial expression and supplies taste to the anterior two-thirds of the tongue via the chorda tympani, but it does not drive tongue movements needed for swallowing. The glossopharyngeal nerve provides taste and sensation to the posterior tongue and innervates a pharyngeal muscle (stylopharyngeus) involved in swallowing, but it does not move the tongue itself. If the tongue’s motor control were compromised, you’d see difficulties with bolus formation and propulsion, tongue weakness, fasciculations, or deviation of the tongue toward the side of weakness when protruded, reflecting loss of CN XII function.

Tongue movement essential for swallowing is controlled by the hypoglossal nerve. This nerve provides motor supply to all intrinsic tongue muscles and to most extrinsic tongue muscles, enabling the tongue to protrude, retract, and precisely shape and push the bolus toward the pharynx during the oral phase of swallowing. When CN XII is intact, the tongue can coordinate these movements smoothly to form a cohesive bolus and propel it posteriorly for swallowing.

Understanding the other nerves helps confirm why this is the correct motor control for the tongue. The trigeminal nerve mainly handles muscles of mastication and sensation to the face, with only limited, indirect influence on tongue sensation, not the primary tongue muscles required for swallowing. The facial nerve primarily controls facial expression and supplies taste to the anterior two-thirds of the tongue via the chorda tympani, but it does not drive tongue movements needed for swallowing. The glossopharyngeal nerve provides taste and sensation to the posterior tongue and innervates a pharyngeal muscle (stylopharyngeus) involved in swallowing, but it does not move the tongue itself.

If the tongue’s motor control were compromised, you’d see difficulties with bolus formation and propulsion, tongue weakness, fasciculations, or deviation of the tongue toward the side of weakness when protruded, reflecting loss of CN XII function.