舌下神经（Hypoglossal nerve），是第十二对脑神经。该神经发源自延髓的舌下神经核，并从延髓的橄榄和锥体之间的橄榄旁沟穿出，然后经行舌下神经道（Hypoglossal canal）。从舌下神经道穿出后，舌下神经与颈椎C1的前侧支汇合，然后缠绕迷走神经，并从内侧颈动脉和内侧颈静脉之间通过。在通过二腹肌后腹的深部后，舌下神经进入舌。

通常可通过让病人伸舌来检查舌下神经的功能。如果一侧的舌下神经功能有障碍，舌伸出时将偏向有障碍的一侧。舌下神经的强健度可通过使病人将舌头顶向面颊，并由医生用手指触动来检查。另一方法是直接检查舌部。

The hypoglossal nerve is the twelfth cranial nerve XII, and innervates muscles of the tongue. The name hypoglossus springs from the fact that its passage is below the tongue, hypo meaning "under", and glossus meaning "tongue", both of which are from Ancient Greek. The nerve is involved in controlling tongue movements required for speech, food manipulation (i.e. formation of bolus), and swallowing.