The Tongue: Innervation and Development
The tongue is a complex muscular organ. Understanding its innervation is critical for clinical neurology and surgery.
| Function | Anterior 2/3 | Posterior 1/3 |
|---|---|---|
| General Sensation | CN V3 (Lingual nerve) | CN IX (Glossopharyngeal) |
| Special Sensation (Taste) | CN VII (Chorda tympani) | CN IX (Glossopharyngeal) |
Motor Innervation:
- All intrinsic and extrinsic muscles: CN XII (Hypoglossal).
- Exception: Palatoglossus muscle is innervated by the Pharyngeal Plexus (CN X).
High-Yield Clinical Pearls:
- CN XII Lesion: The tongue deviates toward the side of the lesion (“lick the wound”).
- Embryology: Anterior 2/3 arises from the 1st and 2nd pharyngeal arches; posterior 1/3 arises from the 3rd and 4th pharyngeal arches.
- Foramen Cecum: The embryonic remnant of the thyroglossal duct, located at the apex of the sulcus terminalis.