Trigeminal nerve is the fifth, very sensitive cranial nerve of the facial skull. It owes its name to its forking into three main branches, one of which also has olfactory functions. It conveys tactile sensations (concerning the sense of touch) of the facial region, which are perceived by the mucous membranes of the oral cavity and the nose when drinking wine or alcohol. These are irritating (irritating, arousing) sensations of a physical and less chemical nature. The trigeminal stimuli are a partial aspect of haptic perception. They are not typical of smell or taste, although the effects are relatively strongly involved in the overall impression.
Trigeminal contributes significantly to olfactory intensity (around 30%). In smokers, nasal-trigeminal sensitivity is reduced, olfactory sensitivity is unaffected. Trigeminal stimuli can be both positive (alcohol, horseradish, menthol, carbonic acid, paprika, pepper, mustard, onion) and negative (ammonia, smoke, sulphur). A typical reaction to trigeminal stimuli is an increased salivary flow. If strongly expressed, this is a pain reaction and thus a precautionary warning signal of the body. The capsaicin contained in paprika (chili, pepperoni) and the piperine contained in pepper cause the trigeminal sensory impressions to be peppery and hot. The alkaloids, which are very similar in their effect, make the brain believe that the temperature in the mouth is critically high and create the feeling of burning. The similarity of hot and hot (both "hot") when consumed is already based on the receptor level . The same receptors also react to food that is too hot (over 43 °Celsius), which "burns" the tongue or palate. The organism counteracts this sensation, which is often painful due to apparent heating, by increasing the blood circulation in the tissue for the purpose of heat dissipation. This leads to a local reddening as in the case of a light burn.