Final answer:
The oral cavity's mucous membrane mainly consists of the epithelium, which secretes mucus and is composed of non-keratinized, stratified squamous cells, and the lamina propria, the underlying connective tissue.
Step-by-step explanation:
The two main components of the mucous membrane of the oral cavity are the epithelium and the lamina propria. The epithelium layer in direct contact with ingested food is responsible for secreting mucus, which aids in moistening and lubricating food. This layer is predominantly composed of non-keratinized, stratified squamous epithelium. Beneath the epithelium lies the lamina propria, which is a layer of connective tissue that provides structural support. Additionally, a thin layer of smooth muscle known as the muscularis mucosae is occasionally included as part of the mucous membrane, facilitating slight movements and contributing to the tissue's elasticity.