oral cavity
Meaning of oral cavity: A precisely bounded space rather than a loose word for mouth, which is why the border with the throat matters so much.
Definition of oral cavity
The oral cavity is the mouth and everything inside it: the lips, the lining of the cheeks, the gums, the front two thirds of the tongue, the floor of the mouth beneath the tongue, the hard palate forming the roof, and the small area behind the wisdom teeth. It ends where the throat begins, at the arch at the back of the mouth.
What is included and what is not?
| Part | Inside the oral cavity |
|---|---|
| Lips and inner cheek lining | Yes |
| Front two thirds of the tongue | Yes |
| Hard palate | Yes |
| Floor of the mouth and the gums | Yes |
| Back third of the tongue, soft palate, tonsils | No, these belong to the oropharynx |
The dividing line runs along the arch formed by the soft palate above and the junction between the front and back portions of the tongue below. It looks arbitrary but is not: the two regions form from different tissue in the embryo, drain to different lymph nodes, and behave differently when disease strikes.
What does it do?
The mouth begins digestion. Teeth break food up, the tongue moves it around and gathers it into a ball, and saliva wets it while enzymes in the saliva start on starch. Saliva also buffers acid, carries antibodies and rinses the surfaces continuously, which is why a dry mouth leads so quickly to decay and infection. The cavity shapes sound for speech, since consonants are formed by tongue, teeth and lips. It also serves as a backup airway when the nose is blocked.
Why does the boundary matter clinically?
Cancers of the two regions are different diseases with different causes. Oral cavity cancer is linked mainly to tobacco and alcohol and is usually managed with surgery first. Cancer of the oropharynx just behind it is frequently driven by human papillomavirus, responds differently to treatment and carries a better outlook when the virus is involved. Staging systems treat the two separately for this reason, so recording exactly where a tumor sits changes what happens next.
What is the lining made of?
Most of the cavity is covered by a layer of flat cells, thicker where chewing wears it as on the gums and hard palate, thinner and more flexible on the cheeks and floor of the mouth. That lining renews rapidly, so it heals fast but is also hit hard by chemotherapy and radiation, producing painful sores. Dentists and an oral surgeon examine it routinely, since a white or red patch that does not settle can be the first visible sign of a serious problem.
Also known as
Used in a sentence
Examination of the oral cavity showed an ulcer on the lateral border of the tongue.
Good to know
The oral cavity ends at the arch at the back of the mouth, and cancers arising just beyond it in the oropharynx have different causes and a different outlook, so the exact site recorded in a report matters.
Word origin
Where “oral cavity” comes from
Oral comes from the Latin os, meaning mouth, and cavity from cavus, meaning hollow.