| oral ulcer | A loss of mucous substance of the mouth showing local excavation of the surface, resulting from the sloughing of inflammatory necrotic tissue. It is the result of a variety of causes, e.g., denture irritation, aphthous stomatitis (stomatitis, aphthous), noma, necrotizing gingivitis (gingivitis, necrotizing, ulcerative), toothbrushing, and various irritants. (12 Dec 1998) |
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| oral vestibule | That part of the mouth bounded anteriorly and laterally by the lips and the cheeks, posteriorly and medially by the teeth and/or gums, and above and below by the reflections of the mucosa from the lips and cheeks to the gums. Synonym: vestibulum oris, buccal cavity, vestibule of mouth. (05 Mar 2000) |
| tuberculosis, oral | Tuberculosis of the mouth, tongue, and salivary glands. (12 Dec 1998) |
| florid oral papillomatosis | Diffuse involvement of the lips and oral mucosa with benign squamous papillomas; microscopically, it resembles verrucous carcinoma, but is not invasive or localised to a specific area of the oral mucosa. (05 Mar 2000) |
| leukoedema, oral | A disorder of the buccal mucosa resembling early leukoplakia, characterised by the presence of filmy opalescence of the mucosa in the early stages to a whitish gray cast with a coarsely wrinkled surface in the later stages, associated with intracellular oedema of the spinous or malpighian layer. (12 Dec 1998) |
| leukoplakia, oral | A white patch seen on the oral mucosa. It is considered a premalignant condition and is often tobacco-induced. When evidence of epstein-barr virus is present, the condition is called hairy leukoplakia (leukoplakia, hairy). (12 Dec 1998) |
| lichen planus, oral | Oral lesions accompanying cutaneous lichen planus or often occurring alone. The buccal mucosa, lips, gingivae, floor of the mouth, and palate are usually affected (in a descending order of frequency). Typically, oral lesions consist of radiating white or gray, velvety, threadlike lines, arranged in a reticular pattern, at the intersection of which there may be minute, white, elevated dots or streaks (wickham's striae). (12 Dec 1998) |
| live oral poliovirus vaccine | Inactivated poliovirus vaccine (IPV), an aqueous suspension of inactivated strains of poliomyelitis virus (types 1, 2, and 3) used by injection; has largely been replaced by the oral vaccine. See: Salk vaccine. (05 Mar 2000) |
| Amberg's lateral sinus line | A line dividing the angle formed by the anterior edge of the mastoid process and the temporal line. (05 Mar 2000) |
| aneurysm of sinus of Valsalva | A congenital thin-walled tubular out pouching usually in the right or non-coronary sinus with an entirely intracardiac course that may rupture into the right or rarely the left heart chambers to form an aortocardiac fistula. (05 Mar 2000) |
| aortic sinus | The space between the superior aspect of each cusp of the aortic valve and the dilated portion of the wall of the ascending aorta, immediately above each cusp. Synonym: sinus aortae, Petit's sinus, Valsalva's sinus. Arlt's sinus, an inconstant depression on the lower portion of the internal surface of the lacrimal sac. Barber's pilonidal sinus, pilonidal sinus occurring in barbers, usually in the web between the fingers, due to the burying of exogenous hairs by the alternate loosening and tightening of tissues of the hand by the manipulation of scissors. (05 Mar 2000) |
| aortic sinus aneurysm | Abnormal dilation of one or more of the three aortic sinuses situated behind the three aortic valve cusps. (05 Mar 2000) |
| apertura sinus frontalis | One of a pair of openings in the floor of the frontal sinuses in the nasal part of the frontal bone, through which the frontal sinuses communicate with the ethmoidal infundibulum via the frontonasal duct. Synonym: apertura sinus frontalis. (05 Mar 2000) |
| apertura sinus sphenoidalis | One of the pair of openings in the body of the sphenoid bone through which the sphenoid sinuses communicate with the sphenoethmoidal recess of the nasal cavity. Synonym: apertura sinus sphenoidalis, sphenoidal sinus aperture. (05 Mar 2000) |
| arrhythmia, sinus | Irregularity of the heart rate related to functioning of the sinoatrial node. (12 Dec 1998) |