The alveolar mucosa is the part of the mucous membrane on the surface of the mouth (oral mucosa) lying between the gums and the lips, cheeks and floor of the mouth. It is "red, smooth and shiny". Its epithelium is thinner than that of the gums, is non-keratinized lining epithelium, and is not connected to underlying tissue by rete pegs. Its connective tissue is loosely ordered, with many blood vessels.
References
Alveolar mucosa Wikipedia(Text) CC BY-SA