The mouth, the oral cavity is topographically divided into the so-called mouth of the mouth and the mouth itself (Fig.). The term "mouth" also refers to the oral opening, enclosed by the lips of the mouth. The borders of the vestibule of the mouth are in the front of the lips and cheeks, and behind the alveolar processes of the jaws and teeth. The oral cavity from above is bounded by the arch of the hard palate; the basis of the bottom of the oral cavity is the maxillary-hypoglossal muscle with the chin-tongue, chin-hypoglossal, hypoglossal-tongue muscles located above it. The posterior border of the oral cavity is represented by a soft palate, with the contraction of the muscles of which a throat opening forms, bounded also by the root of the tongue and the anterior palatopharyngeal arches. When swallowing, the soft palate separates the oral cavity and the oral part of the pharynx from the nasal.
Fig. 1-3. Oral cavity. Fig. 1. Sagittal section. Fig. 2. Front view (corners of the mouth cropped). Fig. 3. frontal section:
1 - palatum durum (hard palate );
2 - dentes (teeth);
3 - labium sup. (upper lip);
4 - rima oris;
5 - labium inf. (underlip);
6 - vestibulum oris (threshold of the mouth);
7 - mandibula;
8 - m. mylohyoideus;
9 - m. genlohyoideus;
10 - gl. sublingualis;
11 - m. genloglossus;
12 - os hyoideum;
13 - isthmus faucium (pharynx);
14 - lingua (tongue);
15 - palatum molle (soft palate);
16 - cavum oris proprium;
17 - frenulum labii sup .;
18 - gingival (gum);
19 - arcus palatoglossus (palatine arch);
20 - tonsilla palatine (palatine tonsil);
21 - uvula (tongue);
22 - frenulum labii inf .;
23 - arcus palatopharyngeus (palatine pharyngeal arch);
24 - plicae palatinae transversae;
25 - venter ant. m. digastrici;
26 - m. buccinator;
27 - corpus adiposum buccae.
The oral cavity is lined with mucous membrane, in the thickness of which is a large number of small salivary glands . The oral mucosa is covered with stratified squamous epithelium, which is located on the connective tissue basis. This layer without a sharp border goes into the submucosal layer. In the gum, tongue, lateral parts of the hard palate and palatal suture area, the submucosal layer is absent. Blood supply, lymphatic drainage and innervation of the oral cavity walls are closely connected with the vascular and nervous systems of the jaws (see). In the oral cavity open ducts of the salivary glands.
It is necessary to point out changes in the structure of the oral mucosa with age: epithelium thinning occurs, signs of degeneration appear, the integrity of the basement membrane is disturbed, connective tissue becomes denser. Marked lengthening of the venous part of the capillaries, reducing their number, slowing blood flow. In the cells of the integumentary epithelium with age increases the tendency to keratinization. All these changes have a significant impact on the occurrence and development of the pathological process, and they must be taken into account when examining or treating a patient.
The oral cavity is the initial part of the digestive tract. Here food is subjected to mechanical and partially chemical processing (see Chewing). The mucosa contains a number of receptors , due to which taste, tactile and pain sensitivity are determined. Pain and temperature sensitivity of the oral mucosa is reduced compared with the skin and varies in different areas.
The mouth contains a diverse microbial flora: in addition to permanent, adapted microbes, microorganisms brought from outside can be present here for a long time. In this regard, there is a constant and random microflora of the oral cavity, and the permanent microflora serves as a biological barrier for microbes that enter the oral cavity from the outside.
With a decrease in the body's resistance, the pathogenic properties of some microbes, usually vegetating in the oral cavity, may appear. Prolonged use of antibiotics can also break the biological barrier and promote the emergence of “medicinal” lesions of the mucous membrane. The causative agents of mucous membrane diseases are most often Candida fungi, enterococci and gram-negative bacteria. Fungal lesions of the mucous membrane are common in aspergillosis, sporotrichosis , etc., as well as in actinomycosis and blastomycosis.
Among the diseases of the mucous membrane most often observed gingivitis (see) and stomatitis (see). Stomatitis can occur with beriberi, blood diseases, after taking certain medications (bismuth, mercury , lead ). In some infectious diseases (measles, scarlet fever ) specific lesions of the oral mucosa develop. Diseases of the oral cavity also include diseases of the teeth, jaws, tongue, lips, salivary glands (see Sialadenitis , Sialolithiasis ).
The so-called precancerous diseases deserve special attention: hyperkeratosis (see), leukoplakia (see), papilloma (see).
Among the mechanical damage to the mucous membrane should be borne in mind ulcers resulting from prolonged trauma to the teeth and dentures (decubital ulcers).
The benign tumors observed in the oral cavity include cyst (see), epulis (see), fibroma (see), lipomas, angiomas. Malignant tumors - cancer and sarcoma - are less common, they often occur in the tongue and palate. Sometimes tumors emanating from the jaw bones, protrude into the vestibule or oral cavity.
See also Teeth, Sky, Tongue.