Mouths

The mouth, or oral cavity, is the entry point to the digestive system in humans and many animals, and it also plays a key role in speech and respiration. It includes the lips, cheeks, palate, tongue, floor of the mouth, gums, and teeth, all lined by mucous membranes. The anterior opening is bounded by the lips and teeth; the roof is formed by the hard and soft palates; the floor by the tongue and mucosa. The oropharyngeal isthmus connects the mouth to the throat.

Teeth are mineralized structures specialized for cutting, tearing, and grinding. In humans there are incisors, canines, premolars, and molars. Teeth develop in two sets: deciduous teeth erupt in early childhood and are later replaced by permanent teeth. The tongue is a muscular organ that manipulates food, aids swallowing, and houses taste buds. The palate separates the oral cavity from the nasal passages and contributes to speech.

Salivary glands—primarily the parotid, submandibular, and sublingual—produce saliva that lubricates, buffers, and begins digestion through enzymes such as amylase. Saliva also helps protect against microorganisms. The mouth’s mucosa is lined by stratified squamous epithelium designed to withstand abrasion, and it hosts a diverse microbiome.

Physiology involves mastication (chewing) to mechanically break down food, mixing with saliva to form a bolus, and swallowing (deglutition) to move the bolus into the esophagus. The mouth contributes to taste perception and speech and, in many animals, to vocalization and respiration.

Common conditions include dental caries, periodontal disease, mucosal lesions, and oropharyngeal cancers. Oral health depends on hygiene, diet, fluoride exposure, and access to care.