trench mouth, common term for Vincent's infection, an ulcerative membranous infection of the gums and mouth, by noncontagious infection, associated with a fusiform bacillus and a spirochete. Poor oral hygiene, nutritional deficiencies, insufficient rest, heavy smoking, and debilitating diseases are predisposing factors to the disease. Epidemics often occur in crowded unsanitary environments, and in former years among soldiers in the field, hence the name "trench mouth." In addition to ulcerations on the gums and mouth, which are painful and bleed freely, there are usually foul breath, increased salivation, and difficulty in swallowing and talking. The acute phase of the disease yields to antibiotic treatment and oxygenating mouth rinses, but attention must also be paid to the underlying dental and medical factors.

mouth organ: see harmonica 1.

mouth, entrance to the digestive and respiratory tracts. The mouth, or oral cavity, is ordinarily a simple opening in lower animals; in vertebrates it is a more complex structure. In humans, the mouth is defined in front and at the sides by the lips, jawbone, teeth, and gums; in the rear it merges with the throat. The roof of the mouth is composed of the hard and soft palates and the floor of the mouth is formed by the tongue, a muscular structure that contains the organs of taste (taste buds). The lips, palates, tongue, and teeth are the major components in speech formation, using the "raw sound" formed in the larynx. The process of digestion begins in the mouth; the chewing and grinding action of the teeth reduces the food to a readily digestible substance. The enzymatic process of converting starch to sugar is initiated by salivary amylase (ptyalin) excreted by the three salivary glands located at the angle of the jawbone and under the tongue. Saliva produced in these glands moistens food, preparing it for processing in the digestive system.

hoof-and-mouth disease: see foot-and-mouth disease.

foot-and-mouth disease, highly contagious disease almost exclusive to cattle, sheep, swine, goats, and other cloven-hoofed animals. It is caused by a virus that was identified in 1897. Among its symptoms are fever, loss of appetite and weight, and blisters on the mucous membranes, especially those of the mouth, feet, and udder. Discharge from the blisters is heavily infected with the virus, as are saliva, milk, urine, and other secretions. Thus the disease is readily spread by contact; by contaminated food, water, soil, or other materials; or through the air. Humans, who seldom contract the disease, may be carriers, as may rats, dogs, birds, wild animals, and frozen meats.

Quarantine, slaughter and complete disposal of infected animals, and disinfection of contaminated material, are prescribed to limit contagion. There is no effective treatment. With vaccines, introduced in 1938, and sanitary controls, foot-and-mouth disease has been excluded or eliminated from North and Central America, Australia and New Zealand, Japan, and Ireland; and occurrences have become infrequent in Great Britain and continental Europe. The disease persists through much of Asia, Africa, and South America.

or oral cavity or buccal cavity

Orifice through which food and air enter the body. It opens to the outside at the lips and empties into the throat at the rear and is bounded by the lips, cheeks, hard and soft palates, and glottis. Its chief structures are the teeth (see tooth), tongue, and palate. It is the site of chewing and speech formation. The mouth is lined by mucous membranes containing small glands that, along with the salivary glands, keep it moist and clear of food and other debris.

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or hoof-and-mouth disease

Highly contagious viral disease of cloven-footed mammals (including cattle), spread by ingestion and inhalation. The afflicted animal develops fever and painful blisters on the tongue, lips, other tissues of the mouth, muzzle or snout, teats, and feet. FMD is endemic in many places. Because of its rapid spread and impact on animal productivity, it is considered the most economically devastating livestock disease in the world. It is not a human health hazard. No effective treatment exists; vaccines control epidemics but have not eliminated them. Since the virus can persist, quarantine, slaughter, cremation or burial of carcasses, and decontamination must be rigorous. Strict surveillance has kept North America largely FMD-free since 1929. In early 2001 a major outbreak occurred in the United Kingdom, followed shortly by outbreaks in The Netherlands and France.

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