Oral mucosa

The oral mucosa is the moist (mucous) membrane covering the inside of the mouth (oral cavity), including the gums. It stretches from the lips, where it is continuous with the skin covering the lips, to the pharynx, a part of the throat behind the mouth. The oral mucosa protects the underlying tissue from e.g. infectious agents and it's involved in salivation.

The oral mucosa histologically composes of three main layers:

• The epithelium, comprising the layer nearest the oral cavity.
• The connective tissue layer, forming the tissue beneath the epithelium.
• The muscle tissue, forming the deepest layer.

The epithelium consists of stratified squamous nonkeratinized epithelium, which in turn is divided into these layers:

• The stratum superficiale, the layer nearest the oral cavity
• The stratum spinosum, the thickest layer
• The stratum basale, the most basal layer, which rests on the basal membrane.

The connective tissue layer mainly consists of connective tissue but also contains blood vessels and immune cells. The muscle layer consists of skeletal muscle.

Numerous minor salivary glands are associated with the oral mucosa and the ducts of more distantly located major salivary glands open into the oral cavity through the mucosa.