Tongue (anatomy), muscular organ in the mouth, the primary organ of taste and important in the formation of speech and in the chewing and swallowing of food. The tongue, which is covered by a mucous membrane, extends from the hyoid bone at the back of the mouth upward and forward to the lips. Its upper surface, borders, and the forward part of the lower surface are free; elsewhere it is attached to adjacent parts of the mouth. The extrinsic muscles attach the tongue to external points, and the intrinsic muscle fibers, which run vertically, transversely, and longitudinally, allow it great range of movement. The upper surface is covered with small projections called papillae, which give it a rough texture. The color of the tongue, usually pinkish-red but discolored by various diseases, is an indication of health.
The tongue serves as an organ of taste, with taste buds scattered over its surface and concentrated toward the back of the tongue. In chewing, the tongue holds the food against the teeth; in swallowing, it moves the food back into the pharynx, and then into the esophagus when the pressure of the tongue closes the opening of the trachea, or windpipe. It also acts, together with the lips, teeth, and hard palate, to form word sounds.
Observations of cow tongues have recently revealed the presence of natural antibiotics on the tongue. The antibiotics are peptides that can prevent infection of cuts in the mouth by resident bacteria. Similar antibiotics are presumed to be produced by the human tongue as well.
See also Palate.
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"Tongue (anatomy)," Microsoft® Encarta® Online Encyclopedia 2000
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