## Mandibular Division (V3) of Trigeminal Nerve ### Anatomical Course and Exit The mandibular division is the largest and only motor-bearing division of CN V. It exits the middle cranial fossa through the **foramen ovale** and divides into anterior (motor) and posterior (sensory) trunks. ### Branches and Their Functions | Branch | Origin | Function | Innervation Target | |--------|--------|----------|--------------------| | Auriculotemporal | Posterior trunk | Sensory + parasympathetic | Temporal skin, parotid gland (postganglionic) | | Lingual | Anterior trunk | Sensory ONLY | Anterior 2/3 tongue (general sensation) | | Inferior alveolar | Anterior trunk | Sensory + motor | Lower teeth, mandible, anterior belly digastric | | Buccal | Anterior trunk | Sensory | Buccal mucosa, lower molars | ### Key Point: **The lingual nerve carries ONLY general sensation (touch, temperature, pain) from the anterior two-thirds of the tongue.** It does NOT carry taste. Taste from the anterior two-thirds of the tongue is supplied by the **chorda tympani branch of CN VII (facial nerve)**, not CN V. ### High-Yield: **Taste pathway (anterior 2/3 tongue):** Chorda tympani (CN VII) → submandibular ganglion → lingual nerve. The lingual nerve is merely the "hitchhiker" carrying CN VII fibres; it does not originate taste sensation. ### Mnemonic: **"Lingual is lonely for taste"** — the lingual nerve (V3) carries only general sensation; taste requires CN VII (chorda tympani). ### Clinical Pearl: In trigeminal neuralgia affecting V3 (mandibular distribution), patients experience severe lancinating pain in the lower face, jaw, and anterior two-thirds of tongue. Taste sensation remains intact because it is CN VII-dependent. Conversely, in Bell's palsy (CN VII palsy), taste is lost but trigeminal sensation is preserved.
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