Nerve Supply of Tongue
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Nerve Supply of the Tongue
Understanding the nerve supply of the tongue is a common yet tricky question in viva exams.
It's essential to approach it in an organized manner by dividing it into:
- Motor Supply
- Sensory Supply
🔌 Motor Supply of the Tongue
The motor supply of the tongue is further divided into three components:
- Somatomotor
- Secretomotor
- Vasomotor
1. Somatomotor Supply
This refers to the supply to the muscles of the tongue.
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All intrinsic and extrinsic muscles of the tongue are supplied by the hypoglossal nerve (CN XII).
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🚨 Exception: The palatoglossus muscle is supplied by the cranial part of the accessory nerve (CN XI) via the pharyngeal plexus.
🔁 Key Point to Memorize:
All the muscles of the tongue (extrinsic and intrinsic) are supplied by the hypoglossal nerve except palatoglossus, which is supplied by the cranial part of the accessory nerve via the pharyngeal plexus.
2. Secretomotor Supply
This refers to the nerves responsible for glandular secretions in the tongue.
- Originates from the superior salivatory nucleus
- Relays in the submandibular ganglion
- Postganglionic fibers reach the tongue via the lingual nerve
3. Vasomotor Supply
This refers to the sympathetic supply to blood vessels of the tongue.
- Derived from sympathetic nerves around the lingual artery
- These carry postganglionic fibers from the superior cervical ganglion
🧷 Sensory Supply of the Tongue
Sensory innervation of the tongue differs for:
- Anterior two-thirds
- Posterior one-third
This variation is due to their embryological origin:
- Anterior 2/3: From the 1st pharyngeal arch
- Posterior 1/3: From the 2nd and 3rd pharyngeal arches
➗ Sensory Supply is of Two Types:
- General Sensation
- Special Sensation (Taste)
🔹 Anterior Two-Third
| Type of Sensation | Nerve |
|---|---|
| General Sensation | Lingual nerve (CN V3) |
| Special Sensation (Taste) | Chorda tympani (branch of CN VII) via lingual nerve |
🔸 Posterior One-Third
| Type of Sensation | Nerve |
|---|---|
| General & Special Sensation | Glossopharyngeal nerve (CN IX) |
🌸 Special Case: Sensory Supply of the Vallecula
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The vallecula is a depression behind the posterior third of the tongue formed by:
- Median glossoepiglottic fold
- Lateral glossoepiglottic folds
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It is not supplied by the glossopharyngeal nerve.
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Instead, it's innervated by the internal laryngeal branch of the superior laryngeal nerve (from vagus nerve, CN X).
🧠 Summary Table
| Area | General Sensation | Special Sensation (Taste) | Motor Supply |
|---|---|---|---|
| Anterior 2/3 of tongue | Lingual nerve (CN V3) | Chorda tympani (CN VII) | Hypoglossal nerve (CN XII) |
| Posterior 1/3 of tongue | Glossopharyngeal nerve (CN IX) | Glossopharyngeal nerve (CN IX) | Hypoglossal nerve (CN XII) |
| Palatoglossus muscle | — | — | Accessory nerve (CN XI) via pharyngeal plexus |
| Vallecula | Internal laryngeal nerve (branch of CN X) | — | — |
📝 All the topics and questions mentioned in this post are explained in detail in my ENT notes - built for exam success and clinical understanding. Get full access by purchasing the notes.