💡 Sensory innervationRegion / function Nerve Anterior two-thirds — general sensation Lingual nerve, V3 Anterior two-thirds — taste Chorda tympani, CN VII, travelling with the lingual nerve Posterior one-third — general sensation and taste Glossopharyngeal nerve, CN IX Epiglottic region Internal laryngeal branch of superior laryngeal nerve, CN X Motor supply to tongue Hypoglossal nerve, CN XII, except palatoglossus (CN X)
💡 Lymphatic drainageRegion Main drainage Tip of tongue Submental nodes Lateral anterior two-thirds Mainly submandibular nodes Central anterior two-thirds Deep cervical nodes, often bilaterally Posterior one-third Deep cervical nodes, particularly upper deep cervical nodes
Clinical pearl: A hypoglossal nerve lesion causes the protruded tongue to deviate toward the side of the lesion because the intact genioglossus pushes the tongue toward the weak side.
💡 Papilla Comparison table — must memorizeFeature Filiform Fungiform Circumvallate Foliate Shape Thread-like Mushroom-like Large, moat-surrounded Leaf-like folds Number Most numerous Numerous 8–12 Several folds per side Location Anterior ⅔ Tip and lateral margins V-shaped row anterior to sulcus terminalis Posterolateral margins Taste buds Absent Present Numerous Present Main function Mechanical Taste Taste Taste Epithelium Keratinized Usually less keratinized Mainly nonkeratinized or lightly keratinized Nonkeratinized Associated glands None specifically None specifically Von Ebner glands Minor salivary glands nearby Nerve for taste — Mainly CN VII CN IX Mainly CN IX Key exam clue Roughness, hairy tongue Red dots at tip Largest; V-shaped row Posterolateral folds
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