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Tongue
Tongue.agr.jpg
A human tongue
Latin lingua
Gray's subject #242 1125
Vein lingual
Nerve Anterior 2/3: lingual nerve & chorda tympani Posterior 1/3: Glossopharyngeal nerve (IX)
Precursor pharyngeal arches, lateral lingual swelling, tuberculum impar[1]
MeSH Tongue
Dorlands/Elsevier Tongue

The tongue is a muscle on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste, as much of the upper surface of the tongue is covered in papillae and taste buds. A secondary function of the tongue is speech. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move. Lastly, the tongue also serves as a natural means of cleaning ones teeth. [2]

Contents

Description

Structure

Drawing of an anterior view of the tongue and oral cavity, with cheeks removed for clarity.
Lateral view of the tongue, with extrinsic muscles highlighted.

The tongue is made mainly of skeletal muscle. The tongue extends much further than is commonly perceived, past the posterior border of the mouth and into the oropharynx.

The dorsum (upper surface) of the tongue can be divided into two parts:

  • an oral part (anterior two-thirds of the tongue) that lies mostly in the mouth
  • a pharyngeal part (posterior third of the tongue), which faces backward to the oropharynx

The two parts are separated by a V-shaped groove, which marks the terminal sulcus

Other divisions of the tongue are based on the area of the tongue:

normal name anatomical name adjective
tongue tip apex apical
tongue blade lamina laminal
tongue dorsum dorsum (back) dorsal
tongue root radix

wanis

tongue body corpus corporeal

wings in the upper flap

Muscles

The intrinsic muscles lie entirely within the tongue, while the extrinsic muscles attach the tongue to other structures.

The extrinsic muscles reposition the tongue, while the intrinsic muscles alter the shape of the tongue for talking and swallowing.

Papillae and taste buds

The oral part of the tongue is covered with small bumpy projections called papillae. There are four types of papillae:

All papillae except the filiform have taste buds on their surface. The circumvallate are the largest of the papillae. There are 8 to 14 circumvallate papillae arranged in a V-shape in front of the sulcus terminalis, creating a border between the oral and pharyngeal parts of the tongue.

There are no lingual papillae on the underside of the tongue. It is covered with a smooth mucous membrane, with a fold (the lingual frenulum) in the center. If the lingual frenulum is too taut or too far forward, it can impede motion of the tongue, a condition called ankyloglossia.

The upper side of the posterior tongue (pharyngeal part) has no visible taste buds, but it is bumpy because of the lymphatic nodules lying underneath. These follicles are known as the lingual tonsil.

The human tongue can detect five basic taste components: sweet, sour, salty, bitter and umami. The sense of taste is referred to as a gustatory sense. Contrary to the popular myth and generations of schoolbooks, there are no distinct regions for tasting different tastes. This myth arose because Edwin G. Boring replotted data from one of Wundt's students (Hanig) without labeling the axes, leading some to misinterpret the graph as all or nothing response.[3] The common conception of taste has a significant contribution from olfaction.

Innervation

Motor innervation of the tongue is complex and involves several cranial nerves. All the muscles of the tongue are innervated by the hypoglossal nerve (cranial nerve XII) with one exception: the palatoglossal muscle is innervated by the X cranial nerve, the Vagus nerve via the pharyngeal plexus.

Sensory innervation of the tongue is different for taste sensation and general sensation.

Vasculature

The underside of a human tongue

The tongue receives its blood supply primarily from the lingual artery, a branch of the external carotid artery. The floor of the mouth also receives its blood supply from the lingual artery. The triangle formed by the intermediate tendon of the digastric muscle, the posterior border of the mylohyoid muscle, and the hypoglossal nerve is sometimes called Pirogov's, Pirogoff's, or Pirogov-Belclard's triangle.[4][5] In area is the lingual artery, a good place to stop uncontrolled bleeding in the tongue.

There is also secondary blood supply to the tongue from the tonsillar branch of the facial artery and the ascending pharyngeal artery.

Length

The average length of the tongue from the oropharynx to the tip is 10 cm (4 in).[6]

Use in pharmacy

The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlain by a plexus of veins. This is an ideal location for introducing certain medications to the body. The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. This is the only (apart from I.V. administration) convenient and efficacious route of administration of nitroglycerin to a patient suffering angina pectoris, chest pain. If the tablet is swallowed, the medication is completely neutralized by the detoxification process of the liver.[citation needed]

Secondary uses

A woman licks a man's face.

In addition to eating and human vocalization, the human tongue has many secondary uses. These include certain forms of kissing known as "tongue kissing" or sometimes "french kissing" in which the tongue plays a primary role. Generally, use of the tongue (such as licking), or interaction between tongues, appears to be a common gesture of affection, not just in humans but throughout the animal kingdom, and particularly in mammals.

Because of its use in both the phenomenon of human sexual interactions, the tongue sometimes is associated with a sensual or erotic connotation. In art the human tongue is often depicted as a seductive instrument, similar to the status of the lips.

The tongue is also one of the more common parts of the human anatomy to be subject to piercing and body modification, a phenomenon that is sometimes associated with certain subcultures or demographics. Tongue piercing has appeared historically in many ancient cultures, and is an increasingly popular trend in the West today, particularly in youth culture.

Showing tongue (tongue out) is an international emotional gesture used primarily by children, or by adults behaving (deliberately or not) in a childish manner.

The human tongue also plays a valuable role in other acts, such as for blowing bubbles with bubble gum, whistling, cleaning, and moistening thread or envelope glue.

Non-human tongues

An okapi using its tongue to scratch an itch

Most multi-cellular animals, that is, members of the subkingdom Metazoa, have tongues or similar organs.

In animals such as dogs and cats, the tongue is often used to clean the fur and body. Rough textures of the tongues of these species helps them to use their tongues to remove oils and parasites by licking themselves and each other. Aside from daily uses for eating and drinking, a dog's tongue acts as a heat regulator. As a dog increases its exercise the tongue will increase in size due to greater blood flow. The tongue hangs out of the dog's mouth and the moisture on the tongue will work to cool the bloodflow.[7][8]

Some animals have prehensile tongues. For example, chameleons, frogs, anteaters, and some species of fish use their tongues to catch prey. Many insects have a type of tongue called a proboscis that is used for the same purpose or, in the case of butterflies, to drink nectar.[9] The corresponding organ in ants is called the hypopharynx.[10] Molluscs have a rough tongue called a radula,[11] which they use to grind food.

Fish generally do not have a true tongue, although there are a few exceptions. The "tongue" of lampreys, for instance, is a rasping organ not homologous with the tongue of tetrapods such as humans.[12]

Tongue rolling

Rolled Tongue
Cloverleaf Tongue

Tongue rolling is the act of rolling the tongue axially into a tube shape. The ability to roll the tongue has been generally believed to depend on genetic inheritance. Tongue rolling was believed to be a dominant trait with simple Mendelian inheritance, and is still commonly used as an example in high school and introductory biology courses. It provided a simple experiment to demonstrate inheritance.

There is little laboratory evidence, though, for the common belief that tongue rolling is inheritable and dominant. A 1975 twin study found that identical twins (who share all of their genes) were no more likely than fraternal twins (who share an average of half) to both have the same phenotype for tongue rolling.[13][14]

Some people are able to generate a high pitched sound by blowing air through their rolled tongue.[citation needed]

Cloverleaf tongue is the ability to fold the tongue in a particular configuration with multiple bends. To the extent to which it is genetic, it is probably a dominant trait distinct from tongue rolling.[14]

As food

The tongues of some animals are consumed and sometimes considered delicacies. In Alaska and the United Kingdom, cow tongues are among the more common. Hot tongue sandwiches are frequently found on menus in Kosher delicatessens in America. In the United Kingdom tongue can often be found at the local grocer, where it is often sold in reformed slices of meat after being ground up and set in gelatine. Taco de lengua (lengua being Spanish for tongue) is a taco filled with beef tongue, and is especially popular in Mexican cuisine. Tongue can also be prepared as birria. Pig and beef tongue are consumed in Chinese cuisine. Duck tongues are sometimes employed in Szechuan dishes, while lamb's tongue is occasionally employed in Continental and contemporary American cooking. Fried cod tongue is a relatively common part of fish meals in Norway and Newfoundland. In the Czech Republic & Poland, a pork tongue is considered a delicacy,and there are many ways of preparing it. In Eastern Slavic countries, pork and beef tongues are commonly consumed, boiled and garnished with horseradish or jelled; beef tongues fetch a significantly higher price and are considered more of a delicacy.

Etymology

The word tongue derives from the Old English tunge, which comes from Proto-Germanic *tungōn.[15] It has cognates in other Germanic languages — for example tonge in West Frisian, tong in Dutch/Afrikaans, tunge in Danish/Norwegian and tunga in Icelandic/Faroese/Swedish. The ue ending of the word seems to be a fourteenth century attempt to show "proper pronunciation", but it is "neither etymological nor phonetic".[15] Some used the spelling tunge and tonge as late as the sixteenth century.

It can be used as a metonym for language, as in the phrase mother tongue. Many languages[16] have the same word for "tongue" and "language".

Figures of speech

A common temporary failure in word retrieval from memory is referred to as the tip-of-the-tongue phenomenon. The expression tongue in cheek refers to a statement that is not to be taken entirely seriously; something said or done with subtle ironic humour. "Tongue twisted" is a term used to described being unable to pronounce a word or phrase correctly. A tongue twister is a phrase made specifically to be very difficult to pronounce. "Tongue-tied" means being unable to say what you want to due to confusion or restriction. The phrase "cat got your tongue" refers to when a person is speechless.

See also

Notes

  1. ^ hednk-024Embryology at UNC
  2. ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. 
  3. ^ Bartoshuk, L.M. (1989). Taste: Robust across the Age Span? Annals of the New York Academy of Sciences 561, pp. 65-75.
  4. ^ named after Nikolai Ivanovich Pirogov
  5. ^ [1]
  6. ^ Robin Kerrod (1997). MacMillan's Encyclopedia of Science. 6. Macmillan Publishing Company, Inc.. ISBN 0028645588. 
  7. ^ http://www.doctordog.com/drdognewsletter/tongue.html
  8. ^ http://www.springerlink.com/content/n3u34u4220384846/
  9. ^ http://magazine.audubon.org/backyard/backyard.html
  10. ^ http://jlibsch.web.wesleyan.edu/Ant/Morphology/Head.html
  11. ^ http://www.qi.com/talk/viewtopic.php?t=917&start=9&sid=a89c9e116f8a414bbfe36cbf6413bc90
  12. ^ Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 298-299. ISBN 0-03-910284-X. 
  13. ^ Discovery Online, The Skinny On... Tongue Rolling
  14. ^ a b Omim - Tongue Curling, Folding, Or Rolling
  15. ^ a b Online Etymology Dictionary
  16. ^ Afrikaans (tong), Albanian (gjuha), Catalan (llengua), Portuguese (língua), French (langue), Maltese, (ilsien), Arabic (لسان lisa-n), Romanian (limba), Russian (Язык yazyk), Bulgarian (ezik), Persian (zabaan), Greek (Γλώσσα glossa), Spanish (lengua), Polish ("język"), Slovak, Czech, Slovene, Bosnian, Serbian, Croatian (jezik), Armenian (?????), Finnish (kieli), Estonian (keel),Filipino ("Dila"], Irish (teanga), Italian(lingua), Latin (lingua), Urdu (zabaan), Aramaic (????/???? liša-na-), Hungarian (nyelv), Hebrew (לשון lashon), Turkish (dil), and Danish (tunge)

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

TONGUE (0. Eng. tonge), in anatomy, a movable organ situated in the floor of the mouth, and serving for the sensation of taste besides helping in the mastication of food, in articulate speech, and in feeling the exact position of any structure within the mouth.

The tongue is divided into a main part or body, a base which looks backward toward the pharynx, a dorsum or upper surface, a root by which it is attached to the hyoid bone and floor of the mouth, a tip which is free and an inferior free surface in contact with the front part of the floor of the mouth and with the lower incisor teeth. Owing to the large amount of muscle in its composition the shape of the tongue varies considerably from time to time. The dorsum of the tongue is covered by stratified squamous epithelium, and, when at rest, is convex both anteroposteriorly and transversely; it is thickly studded with papillae, of which four kinds are recognized.

Filiform papillae are minute conical projections covering the whole of the dorsum, by which term the true upper surface is meant, as well as the tip and borders of the tongue. They are very numerous and contain a short core of subeoithelial mucous membrane covered by a thick coating of epithelial cells, which coating may divide at its tip into a number of thread-like processes.

Fungiform papillae are less numerous than the last, and somewhat resemble "button mushrooms"; they generally contain special taste buds.

Circumvallate papillae are usually from seven to ten in number and are arranged in the form of a V, the apex of which points down the throat. They lie quite at the back of the upper surface of the tongue and each consists of a little flat central mound surrounded by a deep moat, the outer 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 man and consist of a series of vertical ridges occupying a small oval area on each side of the tongue near its base and just in front of the attachment of the anterior pillars of the 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 appearance to that of the dorsum. On it are found numerous circular or oval elevations of the mucous membrane caused by lymphoid tissue (lymphoid follicles), on the summit of the most of which is a mucous crypt or depression. The division between the 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 row of circumvallate papillae. At the apex of this V is a small blind pit, the foran:en caecum. At the lower part of the pharyngeal surface three folds of mucous membrane, called glosso-epiglottis folds, run backward; the middle one passes to the centre of the front of the epiglottis, while the two lateral ones, in 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 fold of mucous membrane called the fraenum linguae, which is attached below to the floor of the mouth. On each side of this the blue outlines of the ranine veins are seen, while 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 article Mouth And Salivary Glands.

The substance of the tongue is composed almost entirely of striped muscle 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 intrinsic muscles. Other muscles, such as the hyo-glossus, stylo-glossus, &c. come from elsewhere and are extrinsic; these are noticed under the head of Muscular System. The arteries of the tongue are derived from the lingual, a branch of the external carotid (see Arteries), while the veins from the tongue return the blood, by one or more veins on each side, into the internal jugular vein (see Veins).

The nerves to the tongue are the (I) lingual or gustatory, a branch of the fifth (see Nerves: Cranial) which supplies the anterior twothirds with ordinary sensation and also, by means of the chorda tymphani which is 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 sensaticn; (3) a few twigs of the superior laryngeal branch of the vagus to the pharyngeal surface of the tongue; and (4) the hypoglossal which is the motor nerve to the muscles.

Embryology. The mucous membrane covering the second and third visceral arches fuses to form the furcula (see Respiratory System). Just in front of this a rounded eminence appears at an 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 c ae cum, 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 developed from the anterior part of the furcula in the middle line, that is to say from the third visceral 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 mid line, however, the isthmus of the 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 supply those arches would help to supply it, but the vagus from the 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.

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 hag (Myxine) among the Cyclostomata, and pike (Esox) among the Internal jugular vein Hypoglossal nerve Spinal accessory nerve Internal carotid artery Digastric muscle Styioltyoid Glosso pharyngeal nerve Parotid gland '"'-', Temporo"'+ maxillary vein External carotid-¦.r artery t Styloglossus`-- ?-.

Ascending palatine artery Internal pterygoid Epiglottis Frenulum epiglottidis M asseter Pharyngeal portion of tongue 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 Comparative Anatomy of Vertebrates, translated by W. N. Parker (London, 1907); C. Gegenbaur, Vergleich. Anat. der Wirbelthiere (Leipzig, 1901); A. Oppel, Lehrb. vergleich. mikroskop. Anat. der Wirbelthiere, Teil 3 (Jena, 1900); Parker and Haswell, Text Book of Zoology (London, 1897). (F. G. P.) Surgery of the Tongue. During infancy it is sometimes noticed that the little band of membrane (fraenum) which binds the under part of the tongue to the middle line of the floor of the mouth is unusually short. The condition will probably right itself as the front part of the tongue takes on its natural growth. In some 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 intellect.

Acute inflammation of the tongue may be caused by the sting of a wasp or by the entrance of septic germs through a wound, and the trouble may end in an abscess.

Chronic inflammation of the tongue may be caused by syphilis, by the irritation of decayed teeth or of a badly-fitting plate of artificial teeth, or by excessive smoking. The condition is one of danger in that it may lead eventually to the tongue becoming the seat of cancer. The treatment demands the removal of every source of irritation. The teeth must be made sound and smooth and must be kept so. Smoking must be absolutely and entirely given up, and salt, mustard, pickles, spirits, aerated 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 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 pipe-stem approaches the tongue. The nerves of the tongue being caught and compressed in the growth, pain is constant and severe, and the movements during mastication cause great distress. The swelling gradually increases in size and, spreading to the floor of the mouth, hinders the free movements of the tongue. In due course it breaks down in the middle and a hard-walled ulcer appears. All this time the small scales of the cancer are finding their way along the lymph-channels and causing a secondary enlargement in the glands just below the jaw and along the side of the neck. Enlargement of the cervical glands is a very serious complication of cancer of the tongue.

The only treatment for cancer of the tongue which is at present known in surgery is the early removal by operation. It not seldom happens that because there is a certain amount of doubt as to the exact nature of the growth in the early weeks delay in operating is reasonably permitted, but during this time there is the risk of the cells of the disease finding their way to the lymphatic system. Still, inasmuch as there may be great difficulty in determining the diagnosis from tertiary syphilitic disease, a course of treatment by iodide of potassium may well be recommended. Syphilis is often the precursor of lingual cancer, and it is impossible to say exactly when the syphilitic lesion becomes malignant. In the case of a cancerous tumour of the tongue being so deeply or so widely attached that its removal cannot be recommended, relief may be afforded by the extraction of most, or all of the teeth, by limiting the food to the most simple and unirritating kinds, and possibly by dividing the great sensory nerves of the tongue.

Missing image
Tongue-1.jpg

Cancer of the tongue is now operated on in advanced cases such as in former years would not have been dealt with by a radical operation. An incision is made beneath the jaw and through the floor of the Pneumogastric nerve .I (Sympathetic I: Ascending pharyngeal artery ?, ` I Odontoid process Fungiform papilla Buccinator Fungiform papilla Superior constrictor muscle Posterior palatine ?` ??Va?

? ? ?

(From Ambrose Birmingham in Cunningham's Text Book of Anatomy.) Horizontal Section through Mouth and Pharynx at the Level of the Tonsils.

Teleostei, teeth are developed on the tongue. In the Amphibia the tailed forms (Urodela) usually have tongues like fishes, though in the genus Spelerpes the organ is very free and can be protruded for a great distance. In the majority of the Anura the tongue is usually attached close to the front of the floor of the mouth so that it can be flapped forward with great rapidity. There are, however, two closely allied families of frogs (Xenopodidae and Pipidae) which form the order of Aglossa, because in them the tongue is suppressed.

In the reptiles the tongue is generally very movable, though this is not the case in the Crocodilia and many of the Chelonia. The forked tongues of snakes and many lizards and the highly specialized telescopic tongue of the chameleon are familiar objects.

In birds the tongue is usually covered with horny epithelium and is poorly supplied with muscles. When it is very protrusible, as in the woodpecker, the movement is due to the hyoid, with the base of the tongue attached, moving forward.

In the Mammalia the tongue is always movable by means of welldeveloped extrinsic and intrinsic muscles, while papillae and glands are numerous. The filiform papillae reach their maximum in the feline family of the Carnivora where they convert the tongue into a rasp by which bones can be licked clean of all flesh attached to them.

Foliate papillae are best seen in the rodents, and when they are la Raphe of tongue Post-pharyngeal lymphatic gland Pharyngo epiglottic fold Anterior palatine arch Circumvallate papilla: Conical papillae mouth, by which the tongue is 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 unimpeded respiration is provided for by the preliminary introduction of a tube into the 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. 0*.)


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Simple English

The tongue is the fleshy muscle inside the mouth. A tongue lets us taste because the top of the tongue is made mostly of taste buds. It is very flexible, so it also helps us eat and talk.

Tongue rolling

File:Rolled tongue
A child rolling their tongue.

Some people can roll their tongue into a tube. The reason why some people are able to and some are not is because of genetic inheritance, meaning that it is based on whether their parents are able to do it. Many schools use tongue rolling as an example of a genetic trait.

People who can roll their tongue can sometimes make a high pitched sound by blowing through their rolled tongue.

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