Which cranial nerve controls tongue muscle activity?

• A. Olfactory
• B. Optic
• C. Spinal Accessory
• D. Hypoglossal

Answer: (D)

Tongue movement is controlled by a motor cranial nerve that supplies all tongue muscles. This nerve travels from the medulla, passes through the hypoglossal canal, and innervates both the intrinsic tongue muscles and most extrinsic muscles (such as genioglossus, hyoglossus, and styloglossus) that shape and move the tongue. That direct motor supply is why this nerve is responsible for tongue muscle activity and why its impairment would noticeably affect tongue movement and articulation. The other nerves have different roles: the olfactory nerve handles smell, the optic nerve handles vision, and the spinal accessory nerve mainly controls neck and shoulder muscles, not the tongue.