Language

The tongue (lingua) is involved in the mechanical processing of food, in the act of swallowing, in taste perception, and in the articulation of speech. The tongue is located in the oral cavity. It is a flattened muscular organ elongated from front to back. The tongue narrows anteriorly, forming the apex of the tongue (apex linguae). The apex passes posteriorly into the wide and thick body of the tongue (corpus linguae), behind which is the root of the tongue (radix linguae). The upper, convex surface is called the back of the tongue (dorsum linguae). The lower surface (facies inferior linguae) is present only in the front part of the tongue. On the sides, the tongue is limited by the right and left rounded edges {margo linguae). The median groove of the tongue (sulcus medianus linguae) runs along the midline from front to back. In the thickness of the tongue, it corresponds to the fibrous plate dividing the tongue into right and left halves. The median sulcus ends in a blind opening (foramen caecum). Forward and to the side of this opening is the terminal sulcus (sulcus terminalis), which has the shape of the letter V. The sulcus separates the body and the root of the tongue. In the area of the root of the tongue is an important immune organ - the lingual tonsil.

The mucous membrane covers the muscles of the tongue from the outside. The surface of the mucous membrane of the back of the tongue is velvety due to the presence of numerous papillae (papillae linguales). Each papilla is an outgrowth of the proper plate of the mucous membrane of the tongue, covered with a multilayered flat epithelium. In the connective tissue base of the papillae there are numerous blood capillaries, in the epithelial cover there are sensitive taste nerve endings.

Filiform and cone-shaped papillae (papillae filiformis et papillae conicae), the most numerous, are diffusely located over the entire back of the tongue, and are about 0.3 mm long. Fungiform papillae (papillae fungi formis) are located mainly on the apex and along the edges of the tongue. Their base is narrowed, and the apex is widened. The length of these papillae is 0.7-1.8 mm, the diameter is 0.4-1.0 mm. In the thickness of the epithelium of the fungiform papillae there are taste buds (3-4 in each papilla), which have taste sensitivity. Grooved papillae (papillae vallatae), or papillae surrounded by a shaft, in the amount of 7-12 are located on the border of the body and root of the tongue, in front of the border groove. The length of the circumvallate papillae is 1-1.5 mm, the diameter is 1-3 mm. The circumvallate papillae have a narrow base and a widened, flattened free part. Around the papilla there is a ring-shaped depression (groove), separating the papilla from the surrounding thickened ridge. Numerous taste buds are located in the epithelium of the lateral surfaces of the circumvallate papilla and the ridge surrounding it.

Foliate papillae (papillae foliatae) are flat plates, 2-5 mm long each, located on the edges of the tongue; they also contain taste buds.

The mucous membrane of the tongue is heterogeneous in different sections. In the area of the back of the tongue, it lacks a submucosa and is immobilely fused with the muscular base of the tongue. The mucous membrane of the root has numerous depressions and elevations, under it lies the lingual tonsil. A well-developed submucosa of the lower surface of the tongue contributes to the formation of folds. Two fringed folds (plicae fimbriatae) are formed at the tip of the tongue. When passing from the lower surface of the tongue to the bottom of the oral cavity along the midline, the mucous membrane forms a sagittally oriented fold - the frenulum of the tongue (frenulum linguae). On the sides of the frenulum along the elevation is the paired sublingual papilla (caruncula sublingualis). On the sublingual papilla, the excretory ducts of the submandibular and sublingual salivary glands of the corresponding side open. Behind the sublingual papilla is located the longitudinal sublingual fold (plica sublingualis), under which lies the salivary gland of the same name.