Ner e supply of tongue
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Nerve Supply of the Tongue
The tongue has a complex nerve supply because it develops from multiple pharyngeal arches. The nerves are divided into sensory (general), special sensory (taste), and motor categories.
1. Sensory (General Sensation - Touch, Pain, Temperature)
| Region | Nerve | Parent Nerve |
|---|---|---|
| Anterior 2/3 (presulcal part) | Lingual nerve | Branch of mandibular division of CN V (Trigeminal) |
| Posterior 1/3 (postsulcal part) + circumvallate papillae | Glossopharyngeal nerve (CN IX) - lingual branch | CN IX |
| Valleculae (area anterior to epiglottis) | Internal laryngeal nerve (branch of superior laryngeal nerve, itself a branch of CN X) | Vagus (CN X) |
- The lingual nerve also supplies the lingual gingivae and mucosa of the floor of the mouth.
- Notably, the circumvallate papillae, although anatomically in the anterior tongue, are supplied by CN IX (not CN V).
2. Special Sensory (Taste)
| Region | Nerve | Via |
|---|---|---|
| Anterior 2/3 (taste buds) | Chorda tympani | Branch of facial nerve (CN VII), travels with the lingual nerve |
| Posterior 1/3 + circumvallate papillae | Glossopharyngeal nerve (CN IX) | Fibers travel to inferior glossopharyngeal ganglion → pons/hypothalamus |
| Area around epiglottis | Internal laryngeal nerve (CN X) | Superior laryngeal branch of vagus |
Why does CN VII not supply the tongue mucosa directly? Embryologically, the second pharyngeal arch (nerve = CN VII) forms the "copula" but is overgrown by the third arch. So CN VII's chorda tympani only reaches the taste buds via the lingual nerve, without supplying the mucosa itself.
3. Motor Supply (All Tongue Muscles)
| Nerve | Muscles Supplied |
|---|---|
| Hypoglossal nerve (CN XII) | ALL intrinsic muscles + styloglossus, hyoglossus, genioglossus (all extrinsic muscles EXCEPT palatoglossus) |
| Vagus (CN X) via pharyngeal plexus | Palatoglossus only (the one exception) |
- The hypoglossal nerve travels through the hypoglossal canal with C1-2 fibers, crosses over the internal and external carotid arteries, passes deep to the lingual nerve, and runs along genioglossus toward the tip of the tongue.
4. Autonomic Supply
- Parasympathetic (to lingual glands): Chorda tympani (CN VII) → lingual nerve → synapses in submandibular ganglion → postganglionic fibers re-enter lingual nerve to the glands.
- Sympathetic (to lingual glands and vessels): Plexuses around the lingual arteries, arising from the carotid plexus.
Quick Summary Table
| Nerve | Function | Region |
|---|---|---|
| Lingual n. (CN V3) | General sensation | Anterior 2/3 |
| Chorda tympani (CN VII via lingual n.) | Taste | Anterior 2/3 |
| Glossopharyngeal n. (CN IX) | General sensation + Taste | Posterior 1/3 + circumvallate papillae |
| Internal laryngeal n. (CN X) | General sensation + Taste | Valleculae / epiglottic area |
| Hypoglossal n. (CN XII) | Motor | All muscles except palatoglossus |
| Vagus n. (CN X) via pharyngeal plexus | Motor | Palatoglossus only |
Sources: The Developing Human - Clinically Oriented Embryology; Scott-Brown's Otorhinolaryngology Head & Neck Surgery
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