part of develops from head mouth adult mouth oral vestibule stoma mouth cavity oral region trophic apparatus cavum oris cavitas oris rima oris vestibulum oris cavital oralis regio oralis The proximal portion of the digestive tract, containing the oral cavity and bounded by the oral opening. In vertebrates, this extends to the pharynx and includes gums, lips, tongue and parts of the palate. Typically also includes the teeth, except where these occur elsewhere (e.g. pharyngeal jaws) or protrude from the mouth (tusks). vestibule of mouth stomatodaeum subdivision of digestive tract future mouth