The entire surface of the oral mucosa is covered by squamous stratified epithelium. The variety of functions that the oral mucosa develops mainly includes protecting the underlying tissues from mechanical, chemical, and biological stimuli, secretion of essential substances, and a sensory function, which allows the perception of temperature, touch, pain, and taste. The oral mucosa can be classified into lining mucosa, masticatory mucosa, and specialized mucosa, with distinctive histological, clinical, and functional features. The latter is absent in some oral cavity regions, where the lamina propria is directly bound to the bone or muscle. Beneath is an underlying connective tissue, known as lamina propria, and a dense irregular connective tissue, the submucosa, which is found at the deepest level. Histologically, the oral mucosa is formed by three layers, a surface squamous stratified epithelium, known as the oral epithelium, whose thickness and degree of keratinization depend on the location and functional requirements.

This is a wet soft tissue membrane that extends from the junction between the vermilion border of the lips and labial mucosa anteriorly to the palatopharyngeal folds posteriorly. The mucous membrane that lines the structures within the oral cavity limits is known as oral mucosa.

Skin attached under tongue