wide, attached to the bottom of a circular depression of the mucous membrane the margin of the depression is elevated to form a wall (vallum), and between this and the papilla is a circular sulcus termed the fossa. They are situated on the surface of the tongue immediately in front of the foramen cecum and sulcus terminalis, forming a row on either side the two rows run backward and medially, and meet in the midline.Įach papillae consists of a projection of mucous membrane from 1 to 2 mm. The circumvallate papillae (or vallate papillae) are dome-shaped structures on the human tongue that vary in number from 8 to 12. Lingual tonsils are found immediately behind the foliate papillae and, when hyperplastic, cause a prominence of the papillae.Ĭircumvallate papilla in vertical section, showing arrangement of the taste-buds and nerves Serous glands drain into the folds and clean the taste buds. Taste buds, the receptors of the gustatory sense, are scattered over the mucous membrane of their surface. Because their location is a high risk site for oral cancer, and their tendency to occasionally swell, they may be mistaken as tumors or inflammatory disease. Sometimes they appear small and inconspicuous, and at other times they are prominent. They are usually bilaterally symmetrical. They are covered with epithelium, lack keratin and so are softer, and bear many taste buds. The foliate papillae appear as a series of red colored, leaf–like ridges of mucosa. They are located on the sides at the back of the tongue, just in front of the palatoglossal arch of the fauces, There are four or five vertical folds, and their size and shape is variable. Magnified diagram of a vertical section through some foliate papillae in a rabbit.įoliate papillae are short vertical folds and are present on each side of the tongue. The larger and longer papillae of this group are sometimes termed papillae conicae. They also contain a number of elastic fibers, which render them firmer and more elastic than the other types of papillae. This epithelium has undergone a peculiar modification as the cells have become cone–like and elongated into dense, overlapping, brush-like threads. These papillae have a whitish tint, owing to the thickness and density of their epithelium. Heavy keratinization of filiform papillae, occurring for instance in cats, gives the tongue a roughness that is characteristic of these animals. Histologically, they are made up of irregular connective tissue cores with a keratin–containing epithelium which has fine secondary threads. At the tip of the tongue, these rows become more transverse. They appear as very small, conical or cylindrical surface projections, and are arranged in rows which lie parallel to the sulcus terminalis. They cover most of the front two-thirds of the tongue's surface. Unlike the other kinds of papillae, filiform papillae do not contain taste buds. They are responsible for giving the tongue its texture and are responsible for the sensation of touch. They are fine, small, cone-shaped papillae found on the anterior surface of the tongue. Filiform papillae are the most numerous of the lingual papillae.
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