How does the tongue work? – InformedHealth.org

Created: December 19, 2011; Last Update: August 23, 2016; Next update: 2020.

“Having something on the tip of your tongue,” “biting your tongue” or speaking “tongue-in-cheek” – this set of muscles covered with mucous membrane appears in so many idioms for good reason: the tongue is a true all-rounder. It is not only very movable, which allows us to speak, suck or swallow in a coordinated way. It is also a sensory organ responsible for tasting and the most sensitive place for our sense of touch. In addition, the tongue contains many cells of the body’s defense system, and even plays a major role in body language.

What is the tongue?

The tongue is an extremely movable set of muscles, which is well-supplied with blood and has many nerves. The tongue muscles have an oblong shape and are covered with a dense layer of connective tissue. Above this layer, a special kind of mucous membrane makes up the surface of the tongue.

The root of the tongue is firmly anchored to the floor of the mouth. The other parts of the tongue can move freely. A strip of tissue called the lingual frenulum connects the underside of the tongue to the floor of the mouth. When you close your mouth, the tongue almost fills up the entire cavity of your mouth. Various muscles keep the tongue “suspended” in the throat: Muscles and ligaments connect the tongue to the hyoid bone (or lingual bone) in the upper part of the throat and to the voice box. The lingual frenulum connects the tongue to the lower jaw. Some muscles even connect the tongue to the base of the skull.

Structure of the tongue

Back, tip, root – the sections of the tongue

The tongue can be divided into different sections:

• Tip and sides of the tongue: These are parts of the movable section of the tongue. These areas are very movable and can perform complex movements.

• Back of the tongue: The upper surface of the tongue is called the back of the tongue. It has many sensory cells for our senses of taste and touch.

• Root of the tongue: The root of the tongue cannot move freely and is connected to the floor of the mouth. It is also called base of the tongue and cannot be seen from outside the mouth.

Rough or velvety: the surface of the tongue

If you look at your tongue in the mirror, you usually see a slightly white, matt surface. The back of the tongue is curved outwards slightly, and in the middle it falls towards the groove that divides the tongue in half lengthwise.

The rough surface of the tongue is due to a special feature of the mucous membrane: the papillae, which appear as many small bumps on the tongue. They are formed by cells bulging up from underneath. These papillae have different jobs to do:

Mechanical papillae

These papillae anchor the mucous membrane firmly to the tongue. They also sense touch so that we can feel the form and texture of food in our mouth.

Taste papillae

Taste papillae make the surface of the tongue much larger. This allows the greatest number of sensory cells embedded there to have contact with food particles for tasting.

Saliva and food residue can get stuck in the grooves between the papillae, especially on the last third of the tongue. This can favor the development of putrefactive (rot-causing) bacteria. Then a whitish film covers the tongue, which also causes bad breath. These bacteria mainly live on remains of protein-rich food like fish, cheese or milk.

Underneath the tongue: always ready for absorption

If you stick out the tip of your tongue and move it upwards you can see the shiny surface underneath: The most noticeable part of it is the lingual frenulum and a vein on either side of it, which can be seen as bluish strings underneath the mucous membrane. The two salivary glands of the lower jaw (submandibular glands) have their ducts where the tongue meets the floor of the mouth.

The mucous membrane of the tongue can absorb some substances – for example medications that are to act quickly. The tablet, fluid or spray is put underneath the tongue, but is not meant to be swallowed. This is called sublingual administration (from the Latin: lingua, meaning “tongue” or “language”).

One example is nitroglycerin spray used in sudden chest pain caused by reduced blood flow through the coronary arteries. This spray acts very quickly because it directly enters the bloodstream. If it was swallowed it would have to pass the stomach and bowel to reach the liver. There it would be only partly broken down before being made suitable for use by the body.

Unique to the body: three-dimensional muscle fibers

The tongue has a great ability to move in all directions. The reason for this is the way the muscle fibers are arranged, which is unique in our body. They run in all three directions: from front to back, from the sides to the middle and from top to bottom. This allows the tongue to make the following movements:

• Extending and contracting: The tongue is the only muscle in our body that can actively contract and extend. When the vertical and horizontal fibers contract at the same time, the tongue becomes narrower and longer: we can stick our tongue out.

• Raising and lowering

• Bending backwards

• Advancing and retracting

• Rounding or hollowing

• Making grooves

• Changing its position: Additional muscles can change the position of the tongue: They pull into the tongue from the front (from the lower jaw), from below and behind (from the hyoid bone) and from above and behind (from the base of the skull).

The tongue’s jobs

Eating and drinking

Being extremely movable, the tongue’s main job is helping us eat: It enables us to suck, turns solid food into a mash that can be swallowed (bolus) and starts the act of swallowing. The tongue can also differentiate many tastes and flavors, which helps us tell whether the food is good for us.

Sucking

The tongue is vitally important, particularly for babies when breastfeeding. It works like a piston, with the cavity of the mouth being the cylinder: When then tongue moves backward in the closed mouth it produces low pressure, which sucks in fluid for drinking.

Chewing, grinding, pressing, salivating

When we chew, the tongue and the cheeks work together to constantly move the food between the teeth so that it can be chewed. The tongue presses the crushed food against the palate and moves this bolus, which is then ready to be swallowed, to the throat. The movements of the tongue also massage small glands directly underneath it and squeeze out saliva. This starts pre-digestion of the food, and the bolus can glide down the esophagus more easily.

Swallowing

The tongue presses the bolus into the throat, which starts the process of swallowing.

Tasting

The tongue’s mucous membrane contains many taste receptors to test the things we eat and drink. They are found in the taste buds where they are arranged like orange sections around a fluid-filled funnel. This is where the chemical substances responsible for taste are washed up and recognized by the sensory cells. The sense of taste used to be vital to our survival because it was the only way to test food and tell the difference between good and poisonous or bad food. Many taste stimuli also trigger increased production of saliva and stomach acid to start digestion.

Touching

The tip of the tongue is the part of the body that is most sensitive to touch. This fine sensitivity to touch has two main tasks: On the one hand, it tests the mechanical characteristics of the food. This high level of sensitivity is the reason why small stones, bone splinters or fish bones feel much larger than they really are. This magnifying effect of the tongue protects us. On the other hand, the tongue searches the entire mouth for remaining rests of food after the first bite.

Speaking

Humans also use the tongue’s movability for speaking. Only when tongue, lips and teeth work together do sounds from the throat turn into understandable letters and words. The tongue is extremely agile and quick: It can produce more than 90 words per minute, using more than 20 different movements. The tongue is essential for pronouncing the consonants “t,” “d,” “l” or the rolling “r.” When pronouncing the letter “k” the tongue is slightly narrowed at the back. And when we say “s,” the tip of the tongue moves backwards. If the tip of the tongue remains between the teeth, we hear a typical lisp.

The fact that the tongue is essential for speaking can also be seen in the ability of parrots to imitate human language: Although they only have a very simple organ of speech with fewer muscle groups than humans, they have an extraordinarily thick tongue. This helps them to produce the sounds of human language. They can touch the tip of their tongue to certain points of articulation in their mouth to imitate human words in a deceptively similar way.

Defending

All the defense cells of the tongue are collectively called the lingual tonsil (tonsilla lingualis). It is found in the back of the mouth at the base of the tongue and is part of the lymphatic tonsillar ring. Together with the palatine tonsils and the adenoids, the lingual tonsil is responsible for defending the body against germs that can come in through the mouth.

Sources

• Menche N. (ed.) Biologie Anatomie Physiologie. Munich: Urban & Fischer/ Elsevier; 2012.

• Pschyrembel W. Klinisches Wörterbuch. Berlin: De Gruyter; 2014.

• Schmidt R, Lang F, Heckmann M. Physiologie des Menschen: mit Pathophysiologie. Heidelberg: Springer; 2011.

• IQWiG health information is written with the aim of helping
  people understand the advantages and disadvantages of the main treatment options and health
  care services.

  Because IQWiG is a German institute, some of the information provided here is specific to the
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  case can be determined by talking to a doctor. We do not offer individual consultations.

  Our information is based on the results of good-quality studies. It is written by a
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  our methods.

Beckman Oral Motor – Impairments: Toung Patterns

Normal Tongue Patterns

Tongue movements are an integral part of the eating process. The following six normal patterns (suckling, simple tongue protrusion, sucking, munching, tongue tip elevation and lateral tongue movements) are presented in order from primitive to more mature patterns.

Suckling

The primary movement in suckling is extension – retraction. The tongue does not extend beyond the lips. Lateral movement is not observed. The tongue may show a semi-bowl shape (cupping). The tongue remains flat and thin. The movement is accomplished with normal tonal changes with rhythmical cycles of extension – retraction. Jaw opening and closing occur in conjunction with tongue movement. This is a normal but primitive pattern.

Simple tongue protrusion

This is a primitive, normal movement associated with the suckling pattern. The tongue extends between the teeth or gums. The tongue remains flat and thin with no abnormal tonal changes. (In the normal population, this may be called tongue thrust, especially by speech pathologists.)

Sucking

The tongue is flat and thin, movement is up and down and is contained within the mouth. The tongue tip elevates to the anterior hard palate. The movement is rhythmical, up-down cycles, with normal tonal changes. This is the primary pattern for adults. The normal rhythm for nutritive sucking is one cycle per second; non-nutritive suck is faster or slower than that rate. A suck occurs with two kinds of pressure: positive pressure and negative pressure. Positive pressure occurs when the jaw elevates, the tongue elevates to the hard palate, and the lips seal. Negative pressure occurs when the jaw drops, the tongue moves away from the hard palate, the posterior cheeks contract, the soft palate elevates, and the lips remained sealed. More coordination is needed for the negative phase of suck.

Tongue tip elevation

This pattern emerges during suck. The anterior one-third of tongue raises upward to contact the upper teeth or alveolar ridge (gums behind upper teeth). It indicates separation of tongue and jaw movement. This movement continues to develop so that the tongue tip can reach the upper lip, even when the jaw is depressed.

Munching

The primary movement of the tongue is up and down with flattening and spreading. Lateral tongue movements are not observed during this pattern. Tongue movements are accompanied by up and down movement of the jaw for chewing and biting. This is a normal tongue pattern observed in early chewing. Food is positioned on the body of the tongue and raised upward to the palate to break up the food prior to swallowing. Soft, lumpy foods, ground meats, and foods that dissolve in saliva (such as crackers), are tolerated with this chewing pattern. All of these patterns are normal, but do not involve any lateral tongue movement. The person cannot move food between molars for chewing. Since this is needed for chewing more viscous foods, s/he fails to move along the continuum of greater variety and separation of tongue, lip, and jaw patterns. The person is limited to a diet which does not require chewing and grinding, such as a pureed diet.

The final tongue movements to consider are:

Lateral tongue movements

The tongue moves to either side, horizontally, to shift food from the center of the mouth to the side. Initially, the tongue may barely shift toward the gum. As skill develops, the tongue will contact the gum or molars. With more control, the tongue will move over the gums or molars. With continued development, the tongue will extend into either cheek. As skills develop, the tongue can move food from one side across the midline to the other side. As movements become more defined, lateral and tongue tip elevations are combined to allow sweeping/cleaning movements of lips, palate, and inside the cheeks. This allows particles of food to be gathered and positioned on the tongue prior to swallowing.

Tongue tremor

Rapid, small movements of the tongue during purposeful activity, such as sucking. A mildly abnormal pattern indicating fatigue. May be observe in nursing infants during sucking.

Exaggerated tongue protrusion

The tongue shows extension (forward movement) beyond the border of the lips which is non-forceful. The movement is a rhythmical extension-retraction pattern. It is similar to a suckle pattern, but is mildly abnormal.

Tongue thrust

The tongue is thickened and bunched. The movement is an outward extension beyond the border of the lips. The movement is forceful, and is associated with an abnormal increase in muscle tone. This may occur as part of a total extension pattern of the body, or with hyperextension of the head and neck. The tongue thrust may make it difficult to insert a utensil into the mouth or may cause food to be ejected during feeding. During drinking, the tongue may thrust into the cup or may protrude in a very tight, bunched fashion beneath the cup.

Tongue retraction

In this abnormal movement, the tongue appears thickened and bunched. The movement is retraction, a strong, pulling back of the tongue into the posterior portion of the oral cavity, associated with abnormal increased muscle tone. The tip of the tongue is not forward and even with the lower lip. It is pulled back toward the middle of the hard palate and may be held firmly against the hard or soft palate. Hard approximation of the tongue with the palate may make insertion of utensils extremely difficult and may make it nearly impossible for any food to be placed on top of the tongue for swallowing. Gagging may be increased for the person with this pattern. Severe tongue retraction can partially block the laryngeal airway contributing to added respiratory problems during feeding. Tongue retraction may be associated with other patterns of retraction or extension in the body (i.e., shoulder retraction or neck extension) or it may be an abnormal pattern used as compensation by a person with poor swallowing patterns. When a person has swallowing difficulties, food which moves rapidly or is very thin may be uncontrollable and life threatening when the tongue is more forward. In such cases, the tongue retracts, resulting in reduction of the size of the pharyngeal opening. This pattern is associated with abnormal increased muscle tone.

Asymmetrical tongue placement or movement

The tongue deviates to one side or the other and may show atrophy on the affected side. It may be accomplished by or associated with abnormal tone in the facial musculature. All movements of the tongue are affected. The tongue deviates, or is pushed toward the weak side. If lateral tongue movement is consistently observed only to one side, it may not be active lateral movement, but rather may be asymmetrical movement toward the weak side.

A Hypotonic tongue

A hypotoic tongue may appear thickened and shows little or no active movement. Fasciculations, small, uncoordinated movements over the body of the tongue, may be observed when the tongue is at rest. These movements may increase during eating, drinking, swallowing and vocalizations.

Dystonic tongue movement

This is a rhythmical, nonfunctional movement of the tongue associated with Parkinson’s or Parkinson’s like symptoms. The ability to interrupt the movement is related to the severity of the disease. With less severe involvement, the pattern can be interrupted during functional activities such as eating or speech, and will not be observed during sleep.

Tongue fasciculations

An abnormal pattern of nonrhythmical, unorganized contraction of individual muscle fibers across the surface of the tongue. May be observed when the tongue is at rest, or following direct stimulation to the tongue. May also be observed during generalized hypertonicity or hypotonicity affecting the whole body. Ankyloglossia – A structural impairment consisting of a shortened lingual frenulum. Body of the tongue is thinned, with the lateral borders elevated. A heart shaped indention may be noted at the front edge of the tongue. Function is limited if the tongue tip can lift less than 1/4″ above the lower incisors. Pseudo Ankyloglossia – A functional impairment in which the body of the tongue is thickened and retracted. The lingual frenulum appears as a prominent white fiber at the center of the tongue tip. The end of the tongue is blunt and thick.

Understanding tongue movement in infants

2 min.

Sept. 2021

This resource is for healthcare professionals

Researchers have used video recording for the first time to see differences in tongue movements between breastfed infants and adults when swallowing.

The tongue is an active muscle and a miracle of coordination. When we drink, the tongue prepares for swallowing by collecting liquid in the mouth, taking the shape of a bowl. It then quickly pushes the liquid back where it is swallowed, while still allowing us to continue breathing.

When we eat, the tongue works by holding the food in the mouth, moving it with saliva and turning it into a lump, which is then pushed back for swallowing. Both adults and infants use a peristaltic type of movement when swallowing.

Language training before birth

Teaching our tongue to do all this work begins in the womb. Before birth, the tongue begins to work by swallowing the amniotic fluid. After the birth of a child, the tongue plays a key role – it helps to squeeze milk out of the mother’s breasts, working in conjunction with the jaws and lips.

When the baby is suckled to the mother’s breast, the nipple and areola are retracted into the mouth so that the nipple reaches the junction of the hard and soft palate. After the baby has sucked well, the tongue begins to work, rhythmically squeezing the nipple with peristaltic movements that squeeze the milk from the mammary gland into the back of the throat, where it is swallowed. Babies naturally coordinate sucking, swallowing, and breathing.

Bottle feeding

This process changes slightly when a baby is bottle fed. The stiffness of the artificial material does not allow the nipple to stretch and take the shape of the baby’s mouth. Peristaltic movements of the tongue are difficult and milk can flow almost without effort on the part of the child.

Parents should remember that during breastfeeding, babies make an effort to get milk. When bottle-feeding, milk often flows very easily and babies can drink the same amount of milk much faster (compared to breastfeeding). This may seem like a good way to save time, but as with many other things in life, slower is often better. If you choose a bottle that works more like a breast, with a slower flow, it allows the baby to stop and pause, the baby enjoys comfortable feeding, and the corresponding satiety signals are developed more slowly.

Research task

Usually everything goes smoothly. But from time to time, babies have difficulty swallowing. This may be due to various problems and they are not always easy to learn and understand.

At the beginning of the atomic era, diagnostics were carried out with the help of X-ray cinematography (filming of X-ray images). For the first time in history, people could see the amazing internal processes in the mouth and observe how the tongue helps to swallow. When concerns arose about the effects of radiation on technicians and patients, the practice was discontinued. Currently, video recording using ultrasound and MRI is often used. However, even with the use of less invasive methods or technologies, scientists still have to find ways to study babies while breastfeeding that do not affect their actions.

Tongue Movement Study

The 2020 study “Quantifying Tongue Movement During Feeding in Infants and Swallowing in Adults” shows patterns. The scientists used ultrasound video to study tongue movements.

“We observed the most organized and rhythmic tongue movements in exclusively breastfed infants, less mobility in those who had conditions that interfere with normal feeding, such as tongue tie, and more “disorganized” movements with bottle feeding than breastfeeding,” the researchers report. “This highlights the key role of tongue movements in breast or bottle sucking.”

Disorganized movements with bottle feeding than with breastfeeding,” researchers report. “This highlights the key role of tongue movements in breast or bottle sucking.” They could also observe differences in tongue mobility before and after treatment in infants with tongue and lip frenulum. And for the first time, pictures of a baby with torticollis during breastfeeding and bottle feeding were obtained. The results showed “slightly less rhythmic sucking than usual during breastfeeding and irregular sucking during bottle feeding.”

Although this study was limited, the use of ultrasound video was effective in obtaining objective information about tongue movements. As more scientists use this technique, we’ll get more information about how language works and we’ll be able to get more accurate information about natural feeding and how to deal with it.

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References

Genna CW, Saperstein Y, Siegel SA, Laine AF, Elad D. Quantitative imaging of tongue kinematics during infant feeding and adult swallowing reveals highly conserved patterns. Physiol Rep. 2021;9:e14685. doi.org/10.14814/phy2.14685

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