| Lingual papillae | |
|---|---|
 Anatomic landmarks of the tongue. Filiform papillae cover most of the dorsal surface of the anterior 2/3 of the tongue, with fungiform interspaced. Just in front of the sulcus terminalis lies a V-shaped line of circumvallate papillae, and on the posterior aspects of the lateral margins of the tongue lie the foliate papillae. | |
 Semidiagrammatic view of a portion of the mucous membrane of the tongue. Two fungiform papillae are shown. On some of the filiform papillae the epithelial prolongations stand erect, in one they are spread out, and in three they are folded in. | |
| Details | |
| Part of | Tongue |
| Identifiers | |
| Latin | papillae linguales |
| NeuroLex ID | birnlex_4102 |
| TA98 | A05.1.04.013 |
| TA2 | 2837 |
| TH | H3.04.01.0.03006 |
| FMA | 54819 |
| Anatomical terminology | |
Lingual papillae (sg.:papilla, from Latin lingua 'tongue' and papilla 'nipple, teat') are small structures on the upper surface of thetongue that give it its characteristic rough texture. The four types of papillae on the human tongue have different structures and are accordingly classified as circumvallate (or vallate), fungiform, filiform, and foliate. All except the filiform papillae are associated withtaste buds.[1]
In living subjects, lingual papillae are more readily seen when the tongue is dry.[2] There are four types of papillae present on the tongue in humans:
Filiform papillae (from Latin filum 'thread' and fōrmis 'having the form of') are the most numerous of the lingual papillae.[1] They are fine, small, cone-shaped papillae found on the anterior surface of the tongue.[3] They are responsible for giving the tongue its texture and are responsible for the sensation of touch. Unlike the other kinds of papillae, filiform papillae do not contain taste buds.[1] They cover most of the front two-thirds of the tongue's surface.[2]
They appear as very small, conical or cylindrical surface projections,[2] and are arranged in rows which lie parallel to thesulcus terminalis. At the tip of the tongue, these rows become more transverse.[2]
Histologically, they are made up of irregularconnective tissue cores with a keratin–containingepithelium which has fine secondary threads.[2] Heavy keratinization of filiform papillae, occurring for instance in cats, gives the tongue a roughness that is characteristic of these animals.
These papillae have a whitish tint, owing to the thickness and density of their epithelium. This epithelium has undergone a peculiar modification as the cells have become cone–like and elongated into dense, overlapping, brush-like threads. They also contain a number of elastic fibers, which render them firmer and more elastic than the other types of papillae. The larger and longer papillae of this group are sometimes termed papillae conicae.
Thefungiform papillae (from Latin fungī 'mushroom' and fōrmis 'having the form of') are club shaped projections on thetongue, generally red in color. They are found on the tip of the tongue, scattered amongst thefiliform papillae but are mostly present on the tip and sides of the tongue. They havetaste buds on their upper surface which can distinguish the five tastes:sweet,sour,bitter,salty, andumami. They have a core ofconnective tissue. The fungiform papillae are innervated by theseventh cranial nerve, more specifically via thesubmandibular ganglion,chorda tympani, andgeniculate ganglion ascending to thesolitary nucleus in thebrainstem.
Foliate papillae (from Latin foliātus 'leafy') are short vertical folds and are present on each side of the tongue.[2] They are located on the sides at the back of the tongue, just in front of thepalatoglossal arch of thefauces.[4][2] There are four or five vertical folds,[2] and their size and shape is variable.[4] The foliate papillae appear as a series of red colored, leaf–like ridges ofmucosa.[2] They are covered withepithelium, lackkeratin and so are softer, and bear many taste buds.[2] They are usually bilaterally symmetrical. Sometimes they appear small and inconspicuous, and at other times they are prominent. Because their location is a high risk site fororal cancer, and their tendency to occasionally swell, they may be mistaken astumors orinflammatory disease. Taste buds, thereceptors of thegustatory sense, are scattered over the mucous membrane of their surface. Serous glands drain into the folds and clean the taste buds.Lingual tonsils are found immediately behind the foliate papillae and, whenhyperplastic, cause a prominence of the papillae.
Thecircumvallate papillae (orvallate papillae, from Latin vallum 'wall') are dome-shaped structures on the human tongue that vary in number from 8 to 12.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.Each papillae consists of a projection of mucous membrane from 1 to 2 mm. 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.The papilla is shaped like a truncated cone, the smaller end being directed downward and attached to the tongue, the broader part or base projecting a little above the surface of the tongue and being studded with numerous small secondary papillae and covered by stratifiedsquamous epithelium.Ducts of lingualsalivary glands, known asVon Ebner's glands empty aserous secretion into the base of the circular depression, which acts like amoat. The function of the secretion is presumed to flush materials from the base of circular depression to ensure that taste buds can respond to changing stimuli rapidly.[5] The circumvallate papillae get special afferent taste innervation from cranial nerve IX, the glossopharyngeal nerve, even though they are anterior to the sulcus terminalis. The rest of the anterior two-thirds of the tongue gets taste innervation from the chorda tympani of cranial nerve VII, distributed with the lingual nerve of cranial nerve V.
Lingual papillae, particularly filiform papillae, are thought to increase the surface area of the tongue and to increase the area of contact and friction between the tongue and food.[2] This may increase the tongue's ability to manipulate a bolus of food, and also to position food between the teeth duringmastication (chewing) andswallowing.
In some diseases, there can be depapillation of the tongue, where the lingual papillae are lost, leaving a smooth, red and possibly sore area. Examples of depapillating oral conditions includegeographic tongue,median rhomboid glossitis and other types ofglossitis. The term glossitis, particularlyatrophic glossitis is often used synonymously with depapillation. Where the entire dorsal surface of the tongue has lost its papillae, this is sometimes termed "bald tongue".[4]Nutritional deficiencies of iron,folic acid, andB vitamins may cause depapillation of the tongue.[4]
Papillitis refers to inflammation of the papillae, and sometimes the termhypertrophy is used interchangeably.[citation needed]
Infoliate papillitis the foliate papillae appear swollen. This may occur due to mechanical irritation, or as a reaction to anupper respiratory tract infection.[4] Other sources state that foliate papilitis refers to inflammation of thelingual tonsil, which islymphoid tissue.[6]
Seven types of papillae are described in domestic mammals, with their presence and distribution being species-specific:[7]-Mechanical papillae: filiform, conical, lentiform, marginal;-Taste papillae: fungiform, circumvallate, foliate
Foliate papillae are fairly rudimentary structures in humans,[1] representing evolutionary vestiges of similar structures in many other mammals.[2]
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