Five basic tastes carried by three cranial nerves, and smell by the olfactory nerve
Expansion
Taste: five basic modalities: sweet, sour, salty, bitter and umami.
| Region | Taste | General sensation |
|---|---|---|
| Anterior two-thirds of tongue | VII (chorda tympani) | V3 (lingual) |
| Posterior third | IX | IX |
| Epiglottis and pharynx | X | X |
All converge on the nucleus of the solitary tract, then thalamus and insular cortex.
Smell: olfactory receptor neurones in the roof of the nasal cavity project through the cribriform plate to the olfactory bulb, then directly to the piriform cortex and amygdala. It is the only sensory system that does not relay through the thalamus before reaching cortex, which is thought to explain the powerful link between smell, emotion and memory.
Clinical points: most of what is called taste is actually smell, so patients with anosmia complain of loss of taste. Head injury shears the olfactory fibres at the cribriform plate, causing anosmia. Olfactory neurones are among the few that regenerate throughout life.