Figure 1.

Lingual taste system. The tongue in sagittal section and sensory ganglia are diagrammed, with nerve projections to the anterior and posterior tongue and papillae. Ordered central projections from ganglia to the brainstem are diagrammed in hatched lines. The chorda tympani/lingual nerve projections, from the geniculate (chorda tympani) and trigeminal (lingual) ganglion neurons to the anterior tongue, enter the tongue in a common bundle but redistribute within the papillae to gustatory (chorda tympani) and non-gustatory (lingual) papilla tissues. Glossopharyngeal nerve projections from petrosal ganglion neurons are to the posterior tongue and circumvallate papilla. Not illustrated, the glossopharyngeal nerve also innervates the gustatory foliate papillae in the posterior lateral walls of the tongue. Boxed diagrams are as follows: The circumvallate papilla with multiple and contiguous taste buds in the papilla epithelial walls. The fungiform papilla with a single apical taste bud in the epithelium, covering a broad connective tissue core with stromal cells and innervation. In addition to directly entering into the taste bud, the chorda tympani nerve extends fibers into the apical epithelium. Non-taste filiform papillae bracket the fungiform papilla. The glossopharyngeal nerve innervates taste buds in the circumvallate papilla and papilla connective tissues. The boxed legend refers to elements in the circumvallate and fungiform papilla diagrams.