The chemical senses generally fall into three categories:
chemesthesis (irritation and pain), olfaction (smell), and
gustation (taste). Traditionally, the emphasis in describing
responsiveness to chemical stimuli has been placed on taste
and smell. The reality is more complex. For example, the
sensory afferents for chemesthetic perception are in close
proximity with olfactory receptors in the nasal cavity and
with gustatory receptors in the oral cavity. Because external
chemical stimuli can be processed by multiple sensory systems,
there has been a great deal of confusion in the literature
on the importance of individual sensory modalities. Generally,
the principal mediating sensory modality may be related
to stimulus type, concentration, and presentation. However,
when perception of external chemical stimuli occurs via the
integrated perception across modalities, the combined perceptual
quality is commonly referred to as flavor.