Table of Contents |
The cheeks, tongue, and palate frame the mouth, which is also called the oral cavity (or buccal cavity).
At the entrance to the mouth are the lips, or labia (singular = labium). Their outer covering is skin, which transitions to a mucous membrane in the mouth proper.
The lips cover the orbicularis oris muscle, which regulates what comes in and goes out of the mouth. The labial frenulum is a midline fold of mucous membrane that attaches the inner surface of each lip to the gum. The cheeks make up the oral cavity’s sidewalls. While their outer covering is skin, their inner covering is mucous membrane. This membrane is made up of non-keratinized, stratified squamous epithelium. Between the skin and mucous membranes are connective tissue and buccinator muscles.
The pocket-like part of the mouth that is framed on the inside by the gums and teeth, and on the outside by the cheeks and lips is called the oral vestibule. Moving farther into the mouth, the opening between the oral cavity and throat (oropharynx) is called the fauces (like the kitchen "faucet"). The main open area of the mouth, or oral cavity proper, runs from the gums and teeth to the fauces.
When you are chewing, you do not find it difficult to breathe simultaneously. The next time you have food in your mouth, notice how the arched shape of the roof of your mouth allows you to handle both digestion and respiration at the same time. This arch is called the palate. The anterior region of the palate serves as a wall (or septum) between the oral and nasal cavities as well as a rigid shelf against which the tongue can push food. It is created by the maxillary and palatine bones of the skull and, given its bony structure, is known as the hard palate. If you run your tongue along the roof of your mouth, you’ll notice that the hard palate ends in the posterior oral cavity, and the tissue becomes fleshier. This part of the palate, known as the soft palate, is composed mainly of skeletal muscle. You can therefore manipulate, subconsciously, the soft palate—for instance, to yawn, swallow, or sing.
A fleshy bead of tissue called the uvula drops down from the center of the posterior edge of the soft palate. Although some have suggested that the uvula is a vestigial organ (an unused organ that is functionless), it serves an important purpose. When you swallow, the soft palate and uvula move upward, helping to keep foods and liquid from entering the nasal cavity. Unfortunately, it can also contribute to the sound produced by snoring. Two muscular folds extend downward from the soft palate, on either side of the uvula. Toward the front, the palatoglossal arch lies next to the base of the tongue; behind it, the palatopharyngeal arch forms the superior and lateral margins of the fauces.
Between these two arches are the palatine tonsils, which are clusters of lymphoid tissue that protect the pharynx. The lingual tonsils are located at the base of the tongue.
The digestive functions of the mouth are summarized in the table below, and you will learn more about some of these structures throughout the rest of this lesson.
| Structure | Action | Outcome |
|---|---|---|
| Lips and cheeks | Confine food between teeth |
|
| Salivary glands | Secrete saliva |
|
| Tongue’s extrinsic muscles | Move tongue sideways, and in and out |
|
| Tongue’s intrinsic muscles | Change tongue shape |
|
| Taste buds | Sense food in mouth and sense taste |
|
| Lingual glands | Secrete lingual lipase |
|
| Teeth | Shred and crush food |
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Source: THIS TUTORIAL HAS BEEN ADAPTED FROM (1) "ANATOMY AND PHYSIOLOGY 2E" ACCESS FOR FREE AT OPENSTAX.ORG/DETAILS/BOOKS/ANATOMY-AND-PHYSIOLOGY-2E. (2) "MICROBIOLOGY" ACCESS FOR FREE AT OPENSTAX.ORG/DETAILS/BOOKS/MICROBIOLOGY. LICENSING (1 & 2): CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL
