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TONGUE (O. Eng. lunge)
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See also:TONGUE (O. Eng. See also:lunge) , in See also:anatomy, a movable See also:organ situated in the See also:floor of the mouth, and serving for the sensation of See also:taste besides helping in the mastication of See also:food, in articulate speech, and in feeling the exact position of any structure within the mouth. The tongue is divided into a See also:main See also:part or See also:body, a See also:base whichTONGUE looks backward toward the pharynx, a dorsum or upper See also:surface, a See also:root by which it is attached to the hyoid See also:bone and floor of the mouth, a tip which is See also:free and an inferior free surface in contact with the front part of the floor of the mouth and with the See also:lower incisor See also:teeth. Owing to the large amount of muscle in its See also:composition the shape of the tongue varies considerably from See also:time to time. The dorsum of the tongue is covered by stratified squamous epithelium, and, when at See also:rest. is See also:convex both anteroposteriorly and transversely; it is thickly studded with papillae, of which four kinds are recognized. Filiform papillae are See also:minute conical projections covering the whole of the dorsum, by which See also:term the true upper surface is meant, as well as the tip and See also:borders of the tongue. They are very numerous and contain a See also:short core of subepithelial mucous membrane covered by a thick coating of See also:epithelial cells, which coating may See also:divide at its tip into a number of See also:thread-like processes. Fungiform papillae are less numerous than the last, and somewhat resemble " See also:button mushrooms "; they generally contain See also:special taste buds. Circumvallate papillae are usually from seven to ten in number and are arranged in the See also:form of a V, the See also:apex of which points down the See also:throat. They See also:lie quite at the back of the upper surface of the tongue and each consists of a little See also:flat central See also:mound surrounded by a deep See also:moat, the See also:outer See also:wall of which is slightly raised above the surface, and it is to this that the papillae owe their name. Both sides of the moat have taste buds embedded in them, while into the bottom small serous glands open. Foliate papillae are only vestigial in See also:man and consist of a See also:series of See also:vertical ridges occupying a small See also:oval See also:area on each See also:side of the tongue near its base and just in front of the See also:attachment of the anterior pillars of the See also:fauces. (See PHARYNX.) The posterior surface or base of the tongue forms part of the anterior wall of the pharynx and has a quite different See also:appearance to that of the dorsum. On it are found numerous circular or oval elevations of the mucous membrane caused by lymphoid See also:tissue (lymphoid follicles), on the See also:summit of the most of which is a mucous See also:crypt or depression. The See also:division between the See also:superior or oral surface of the tongue and the posterior or pharyngeal is sharply marked by a V-shaped shallow groove called the sulcus terminalis which lies just behind and parallel to the V-shaped See also:row of circumvallate papillae. At the apex of this V is a small See also:blind See also:pit, the foramen caecum. - At the lower part of the pharyngeal surface three folds of mucous membrane, called glosso-epiglottic folds, run backward; the See also:middle one passes to the centre of the front of the epiglottis, while the two lateral ones, in See also:modern anatomy often called pharyngo-epiglottic folds, pass backward and outward to the fossa of the tonsil. On the inferior free surface of the tongue, that is to say, the surface which is seen when the mouth is looked into and the tongue turned up, there is a median See also:fold of mucous membrane called the fraenum linguae, which is attached below to the floor of the mouth. On each side of this the See also:blue outlines of the ranine See also:veins are seen, while See also:close to these a little fold on each side, known as a plica fimbriata, is often found. It must not, however, be confused with the plica sublingualis described in the See also:article MOUTH AND SALIVARY GLANDS. The substance of the tongue is composed almost entirely of striped muscle See also:fibres which run in different directions. Some of these bundles, such as the superficial, deep, transverse and oblique linguales are confined to the tongue and are spoken of as See also:intrinsic muscles. Other muscles, such as the hyo-glossus, stylo-glossus, &c. come from elsewhere and are extrinsic; these are noticed under the See also:head of See also:MUSCULAR See also:SYSTEM. The See also:arteries of the tongue are derived from the lingual, a See also:branch of the See also:external See also:carotid (see ARTERIES), while the veins from the tongue return the See also:blood, by one or more veins on each side, into the See also:internal jugular vein (see VEINS). The nerves to the tongue are the (1) lingual or gustatory, a branch of the fifth (see NERVES: See also:Cranial) which supplies the anterior two-thirds with See also:ordinary sensation and also, by means of the chorda tymphani which is See also:bound up with it, with taste sensation; (2) the glossopharyngeal which supplies the circumvallate papillae and posterior third of the tongue with taste and. ordinary sensation; (3) a few twigs of the superior laryngeal branch of the vagus to the pharyngeal surface of the tongue; and (¢) the hypoglossal which. is the motor See also:nerve to the muscles. See also:Embryology. The mucous membrane covering the second and third visceral See also:arches fuses to form the furcula (see See also:RESPIRATORY SYSTEM). Just in front of this a rounded See also:eminence appears at an See also:early date in the ventral wall of the pharynx to form the tuberculum impar which is separated from the furcula by the depression known as the sinus arcuatus. This tuberculum impar gradually grows to form the central part of the tongue in front of the foramen ccum, while the anterior part of the organ is derived from two lateral swellings which appear in the floor of the mouth and surround the tuberculum impar antero-laterally. The posterior third, or pharyngeal part, is See also:developed from the anterior part of the furcula During See also:infancy it is sometimes noticed that the little See also:band of membrane (fraenum) which binds the under part of the tongue to the middle See also:line of the floor of the mouth is unusually short. The See also:condition will probably right itself as the front part of the tongue takes on its natural growth. In some See also:children the tongue is so large that it hangs out of the mouth, scratching itself upon the teeth. This condition is likely to be associated with weak See also:intellect. Acute inflammation of the tongue may be caused by the sting of a See also:wasp or by the entrance of septic germs through a See also:wound, and the trouble may end in an See also:abscess. Chronic inflammation of the tongue may be caused by syphilis, by the irritation of decayed teeth or of a badly-fitting See also:plate of artificial teeth, or by excessive smoking. The condition is one of danger in that it may See also:lead eventually to the tongue becoming the seat of See also:cancer. The treatment demands the removal of every source of irritation. The teeth must be made See also:sound and smooth and must be kept so. Smoking must be absolutely and entirely given up, and See also:salt, See also:mustard, pickles, See also:spirits, aerated See also:waters, and everything else which is likely to be a cause of irritation must be avoided. Cancer of the tongue is the result of chronic irritation which produces an excessive growth of the scaly covering of the tongue and causes an invasion of the deeper parts of the tongue by the scales. It is more often found in men than See also:women and is usually associated with a hard swelling at one side of the tongue—perhaps near a jagged tooth or at the spot where the end of the See also:pipe-See also:stem approaches the tongue. The nerves of the tongue being caught and compressed in the growth, See also:pain is See also:constant and severe, and the movements during mastication cause See also:great See also:distress. The swelling gradually in-creases in See also:size and, spreading to the floor of the mouth, hinders the free movements of the tongue. In due (From See also:Ambrose See also:Birmingham in See also:Cunningham's See also:Text See also:Book of Anatomy.) course it breaks down in the middle See also:Horizontal See also:Section through Mouth and Pharynx at the Level of the Tonsils. and a hard-walled See also:ulcer appears. All this time the small scales of the cancer Teleostei, teeth are developed on the tongue. In the See also:Amphibia are finding their way along the See also:lymph-channels and causing a the tailed forms (Urodela) usually have See also:tongues like fishes, though in secondary enlargement in the glands just below the See also:jaw and along the genus Spelerpes the organ is very free and can be protruded for the side of the See also:neck. Enlargement of the cervical glands is a very a great distance. In the See also:majority of the Anura the tongue is usually serious complication of cancer of the tongue. attached close to the front of the floor of the mouth so that it can The only treatment for cancer of the tongue which is at See also:present be flapped forward with great rapidity. There are, however, two known in See also:surgery is the early removal by operation. It not seldom closely allied families of frogs (Xenopodidae and Pipidae) which happens that because there is a certain amount of doubt as to the form the See also:order of Aglossa, because in them the tongue is suppressed. exact nature of the growth in the early See also:weeks delay in operating In the See also:reptiles the tongue is generally very movable, though is reasonably permitted, but during this time there is the See also:risk of this is not the See also:case in the Crocodilia and many of the Chelonia. The the cells of the disease finding their way to the lymphatic system. forked tongues of See also:snakes and many lizards and the highly specialized Still, inasmuch as there may be great difficulty in determining the telescopic tongue of the See also:chameleon are See also:familiar See also:objects. diagnosis from See also:tertiary syphilitic disease, a course of treatment by In birds the tongue is usually covered with horny epithelium iodide of See also:potassium may well be recommended. Syphilis is often and is poorly supplied with muscles. When it is very protrusible, the precursor of lingual cancer, and it is impossible to say exactly as in the See also:woodpecker, the See also:movement is due to the hyoid, with the when the syphilitic See also:lesion becomes See also:malignant. In the case of a base of the tongue attached, moving forward. cancerous See also:tumour of the tongue being so deeply or so widely attached In the See also:Mammalia the tongue is always movable by means of well- that its removal cannot be recommended, See also:relief may be afforded by developed extrinsic and intrinsic muscles, while papillae and glands the extraction of most, or all of the teeth, by limiting the food to the are numerous. The filiform papillae reach their maximum in the most See also:simple and unirritating kinds, and possibly by dividing the feline See also:family of the See also:Carnivora where they convert the tongue into great sensory nerves of the tongue. a rasp by which bones can be licked clean of all flesh attached to Cancer of the tongue is now operated on in advanced cases such as in them. former years would not have been dealt with by a See also:radical operation. Foliate papillae are best seen in the rodents, and when they are An incision is made beneath the jaw and through the floor of the in the middle line, that is to say from the third visceral See also:arch. The sinus arcuatus becomes gradually shallower as these two parts of the tongue grow together and eventually is indicated by the sulcus terminalis; in the See also:mid line, however, the See also:isthmus of the See also:thyroid grows down from it, forming the thyro-glossal duct the remains of which are seen in the foramen caecum (see DUCTLESS GLANDS). It will be seen that the tongue is developed in connexion with the first, second and third visceral arches, and it is therefore to be expected that the fifth, seventh and ninth nerves which See also:supply those arches would help to supply it, but the vagus from the See also:fourth arch reaches it in addition, while the fact that most of the muscular substance of the tongue is supplied by the hypoglossal nerve is explained on the theory that some of the cervical skeletal musculature has grown cephalad into the tongue and has carried its nerve with it. well developed the circumvallate papillae are few, often only one on each side. In the lemurs an under tongue or sub lingua is found, which is probably represented by the piicae fimbriatae under the human tongue, and by some morphologists is regarded as the homologue of the whole tongue of the lower vertebrates, the greater part of the mammalian tongue being then looked upon as a new formation. For further details and literature see R. Wiedersheim's See also:Comparative Anatomy of Vertebrates, translated by W. N. See also:Parker (See also:London, 1907) ; C. See also:Gegenbaur, Vergleich. Anat. der Wirbelthiere (See also:Leipzig, 1901); A. See also:Oppel, Lehrb. vergleich. mikroskop. Anat. der Wirbelthiere, Tell 3 (See also:Jena, 1900) ; Parker and Haswell, Text Book of See also:Zoology (London, 1897). (F. G. P.) Surgery of the Tongue. Comparative Anatomy. The tongue is present in fishes but it is an immovable swelling in the floor of the mouth and is practically devoid of muscles. In the See also:hag (Myxine) among the See also:Cyclostomata, and See also:pike (Esox) among the Internal jugular vein Hypoglossal nerve See also:Spinal See also:accessory nerve Internal carotid artery Digastric muscle Pneumogastric nerve l I I I I Sympathetic Ascending pharyngeal artery Odontoid See also:process ,y;l,tis_ a `<y *! See also:Post pharyngeal lymphatic gland Superior constrictor muscle Posterior See also:palatine arch Tonsil Pharyngo.epiglottic fold Stylohyoid Glosso• pharyngeal nerve Parotid gland Temporo• maxillary vein External carotid artery Styloglossus Ascending palatine artery Internal pterygoid Epiglottis Frenulum epiglottidis Masseter Pharyngeal portion of tongue Fungiform papilla Buccinator Anterior palatine arch Circumvallate papilla Raphe of tongue Conical papillae mouth, by which the tongue is See also:drawn out and rendered easily accessible, the arteries being leisurely secured as the tissues are cut across. The upper part of the gullet is plugged by a sponge so that no blood can enter the lungs, and urlimpeded respiration is provided for by the preliminary introduction of a See also:tube into the See also:windpipe. Through the incision which is made below the jaw the infected lymphatic glands are removed. To Dr Kocher of Berne the profession and the public are indebted for this important advance in the treatment of this disease. (E. Additional information and CommentsThere are no comments yet for this article.
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