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 penisdorsum (upper surface) of the tongue can be divided into two parts:
The two parts are separated by a V-shaped groove, which marks the sulcus terminalis (or terminal sulcus).
Since the tongue contains no bony supports for the muscles, the tongue is an example of a muscular hydrostat, similar in concept to an octopus arm. Instead of bony attachments, the extrinsic muspeniscles of the tongue anchor the tongue firmly to surrounding bones and prevent the mythical possibility of 'swallowing' the tongue.
Other divisions of the tongue, are based on the area of the tongue:
|normal napenisme||anatomical name||adjective|
|tongue blade||lamina||lapenisminal penis|
|tongue dorsum||dorsum (back)||dorsal|
The extrinsic muscles reposition the tongue, while the intrinsic muscles alter the shape of the tongue for talking and swallowing.
|Genioglossus muscle||mandible||hypoglossal nerve||protrudes the tongue as well as depressing its center.|
|Hyoglossus muscle||hyoid bone||hypoglossal nerve||depresses the tongue.|
|Styloglossus muscle||styloid process||hypoglossal nerve||elevates and retracts the tongue.|
|Palatoglossus muscle||palatine aponeurosis||pharyngeal branch of vagus nerve||depresses the soft palate, moves the palatoglossal fold towards the midline, and elevates the back of the tongue.|
Four paired intrinsic muscles of the tongue originate and insert within the tongue, running along its length. These muscles alter the shape of the tongue by: lengthening and shortening it, curling and uncurling its apex and edges, and flattening and rounding its surface.
The tongue is often cited as the "strongest muscle in the body," a claim that does not correspond to any conventional definition of strength.
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. The common conception of taste has a significant contribution from olfaction.
Sensory innervation of the tongue is different for taste sensation and general sensation.
The tongue also has a distinct use in both male and female forms of oral sex, and is typically used to a great extent in foreplay and traditional sexual intercourse as well. 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 and whistling.
Injury to the tongue is often very painful. The muscle is vulnerable to various cancers.
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 cool down further cooling down the bloodflow.
Some animals have prehensile tongues. For example, chameleons, frogs, salamanders 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. The corresponding organ in ants is called the hypopharynx. Molluscs have a rough tongue called a radula, which they use to grind food.
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.
Some people are able to generate a high pitched sound by blowing air through their rolled tongue.
Tongues are also used in sausage making. Historically, buffalo tongue was once considered an especially exquisite dish, and is one of the reasons for the American Bison being hunted by humans to the point of near extinction.