Oral cancer

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Anatomy and physiology of the oral cavity

The oral cavity (mouth) includes the lips, cheeks, palate (roof of the mouth), floor of the mouth and the part of the tongue in the mouth (oral tongue). A mucous membrane lines and protects the inside of the mouth. The structures in the oral cavity play an important role in speech, taste and the first steps of digestion.

Note: The lining of the lips and cheeks (buccal mucosa) are not shown.


The oral cavity begins at the border between the skin and the lips (vermillion border). The roof of the mouth is formed by the hard palate. The oral cavity leads into the oropharynx, which includes the soft palate, the back of the tongue and the tonsils. The inner surface of the cheeks forms the sides of the oral cavity. The lowest part of the oral cavity is the floor of the mouth, which is covered by the tongue.

The oral cavity can be divided into specific areas, including:

  • lips
  • labial mucosa (inner lining of the lips)
  • commissure of lips (where the upper and lower lips meet at the corner of the mouth)
  • vestibule (a space bounded by the teeth and gums on the inside and the mucosal surface of the lips and cheeks on the outside)
  • oral tongue (the front two-thirds of the tongue)
  • floor of the mouth
  • buccal mucosa (the inner lining of cheeks)
  • gingiva (gums)
  • retromolar trigone (the area just behind the back molars in the lower jaw)
  • hard palate (the bony part at the front of the roof of the mouth)
  • teeth
  • lower jaw (mandible)
  • upper jaw (maxilla)


The function of the oral cavity and its structures is to begin the process of digestion. The oral cavity receives food, chews and mixes it with saliva and then begins the swallowing process. The taste buds on the tongue provide the different sensations of taste. The oral cavity plays an important role in speech. The mouth is also used for breathing, drinking, facial expressions and social interactions (such as kissing).


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