The oral cavity can be subdivided broadly into three areas consisting of the vestibule, oral cavity proper, and oropharynx.
The vestibule: it is the space that is present between the lips or cheeks laterally and the dentition medially.
Oral cavity proper: It lies inside the dental arches and is bounded
posteriorly by the anterior pillar of the fauces, or palatoglossal arch.
Oropharynx: It lies posterior to the palatoglossal arch, and includes the posterior one-third of the tongue, palatine tonsils, soft palate, and visible posterior wall.
Major areas of oral cavity: oral cavity proper, oropharynx, and vestibule. The vestibule is referred to as “buccal” posteriorly and “labial” anteriorly where it contacts the cheek and lip, respectively.