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Entry of material into the airways from the mouth, pharynx or stomach.

Belching is expulsion of gas from the upper digestive tract through the mouth. It involves movement across upper digestive junctions and can release swallowed air. It differs from expulsion of stomach contents in vomiting.

Dysphagia means difficulty swallowing. It can involve preparation and transfer of material in the mouth, passage through the pharynx or movement down the oesophagus. These stages require coordinated muscle activity, sensation and neural control. Dysphagia names a functional difficulty rather than one unique disease or anatomical lesion. ^[ref]

Swallowing also protects the airway: food transport and temporary closure of the breathing passage must be coordinated. A delay in initiating the response and a mechanical obstruction can both disrupt swallowing through different mechanisms. Difficulty moving a bolus, pain during swallowing and entry into the airway are related observations but should not be treated as identical definitions.

A lip is a movable fold at the entrance to the mouth, with skin externally and oral mucosa internally. The lips contain the orbicularis oris muscle, whose contraction helps close and shape the oral opening. Their sensory supply helps guide contact with food and objects.^[ref]

The oral seal has several functions. During eating it helps retain food; during speech, closure and release can interrupt airflow, while rounding changes the geometry of the vocal tract. A bilabial stop such as /p/ uses contact between both lips, whereas a rounded vowel uses an open but reshaped outlet. The visible fold and the muscle controlling it are related structures, rather than identical anatomical objects.

The mouth is the entrance to the digestive tract and a movable part of the vocal tract. Its cavity is bounded by the lips, cheeks, palate and floor of the mouth, with the tongue occupying much of the space. The teeth break food into smaller pieces while the tongue and cheeks position it for chewing and swallowing.^[ref]

Mechanical processing and chemical processing cooperate: mixing food with saliva makes a movable bolus and exposes it to salivary components. The same cavity also changes shape during speech. Opening the jaw or repositioning the tongue changes the passage through which air and sound travel, so digestive anatomy is also an articulatory instrument.

Attribution or localization of an odor contribution to an object or event, especially food in the mouth. Mouth localization does not entail gustatory receptor transduction. Controlled route, attention and rating manipulations are needed to distinguish localization, quality and verbal labeling.

Planning and executing learned mouth and facial movements. Speech and nonspeech versions can constrain whether an impairment concerns articulatory sequencing, broader motor planning or additional language processes.

The roof of the mouth and its supporting anatomy. In avian comparisons, contacts among the vomer, palatine bone, pterygoid bone and braincase are important for cranial kinesis.

The parotid gland is a major salivary gland near the side of the face, anterior and inferior to the ear. Its duct crosses the cheek to reach the mouth. Branches of the facial nerve traverse the gland, an important spatial relation distinct from its secretory innervation.

Regurgitation is return of contents toward the mouth without the full coordinated expulsive pattern of vomiting. It describes a direction of movement and observed event rather than a unique cause. The distinction matters when interpreting symptoms or recording digestive behavior.

Olfaction involving food volatiles reaching the nasal cavity from the mouth through the nasopharynx. It contributes to flavor and often to oral attribution. Changing this route can alter transport and peripheral stimulation as well as object context.

A salivary gland produces fluid delivered into the mouth through ducts. Its secretions lubricate surfaces and contribute to the oral environment and digestion. The parotid gland, submandibular gland and sublingual gland have different locations and secretory contributions.

Salivary secretion produces and modifies the fluid entering the mouth from salivary glands. Secretory cells supply components that are further modified during passage through ducts. Changes in flow rate can therefore change composition as well as total fluid volume.

Twelve resting volunteers wore a water-perfused suit. Tubes covered the torso, upper arms and legs; the right forearm remained uncovered for laser Doppler blood-flow measurement. Six thermocouples estimated mean skin temperature; a sublingual thermocouple measured oral temperature. A dry-air capsule measured local sweat output from outgoing air moisture. ^[ref]

After two control scans near $34{}^{\circ }\mathrm{C}$ skin temperature, the suit cooled and then warmed the skin. Mean oral temperature was $36.6{}^{\circ }\mathrm{C}$ during both cooling and early warming; mean skin readings were $30.5$ and $38.2{}^{\circ }\mathrm{C}$. Cutaneous vascular conductance fell during cooling and rose during warming. The inference is that compensatory blood-flow responses can precede an appreciable internal temperature change. ^[ref]

Repeated baselines controlled comparison within participants; closed mouths reduced oral-probe cooling artifacts. A later control with reduced oral temperature was excluded. Oral temperature is a proxy, local flow is not whole-body heat transfer, and the fixed condition order leaves time effects possible. Brain imaging measured regional blood flow, not direct neuron firing or causal necessity. ^[ref]

The soft palate is the mobile posterior part of the roof of the mouth. Its elevation helps separate the nasal and oral pharyngeal routes during swallowing and some speech sounds. Muscular control changes a shared passage rather than supplying a permanently sealed partition.

The sublingual gland is a major salivary gland beneath the oral lining beside the tongue. Numerous small ducts open into the floor of the mouth. Its location distinguishes it from the deeper and more posterior submandibular gland.

The submandibular gland is a major salivary gland associated with the region beneath the mandible and the floor of the mouth. Its duct passes forward to open near the tongue. A ductal blockage therefore affects a defined drainage route rather than all oral secretions equally.

Vomiting is the coordinated expulsion of upper digestive contents through the mouth. Neural control recruits digestive, respiratory and abdominal mechanisms. It is distinct from the sensation of nausea and from retching, which can occur without expulsion.