The oral cavity is the most proximal portion of the aerodigestive tract, and is continuous posteriorly with the oropharynx.
The oral cavity includes the lips anteriorly. For purposes of staging oral carcinoma according to the 8th edition of the AJCC TNM staging system, the oral cavity starts at the portion of the lip that contacts the opposed lip (wet mucosa) and excludes the dry vermilion lip.
The oral cavity is divided into a number of subsites both anatomically and for the purposes of cancer staging:
- mucosal lip
- buccal mucosa
- upper alveolar ridge (mucosa overlying alveolar process of maxilla)
- lower alveolar ridge (mucosa overlying alveolar process of mandible)
- retromolar gingiva (retromolar trigone)
- floor of mouth
- anterior two-thirds of the tongue (oral tongue; posterior third is part of the oropharynx)
- hard palate