Tongue a human tongue Latin



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Tongue

Tongue



A human tongue

Latin

lingua

Gray's

subject #242 1125

Vein

lingual

Nerve

lingual nerve

Dorlands/Elsevier

l_11/{{{DorlandsSuf}}}

The tongue is the large bundle of skeletal muscles on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste. Much of the surface of the tongue is covered in taste buds. The tongue, with its wide variety of possible movements, assists in forming the sounds of speech. It is sensitive and kept moist by saliva, and is richly supplied with nerves and blood vessels to help it move.[1]

Etymology


The word tongue can be used as a metonymy for language, as in the phrase mother tongue. In fact, Albanian (gjuha), Catalan (llengua), Portuguese (língua), French (langue), Maltese, (ilsien), Arabic (لسان lisān), Romanian (limba), Russian (язык yazyk), Bulgarian (ezik), Persian (zabaan), Greek (γλώσσα), Spanish (lengua), Polish, Slovak, Czech, Slovene, Bosnian, Serbian, Croatian (jezik), Armenian (լեզու), Finnish (kieli), Estonian (keel), Irish, Italian (lingua), Latin (lingua), Urdu (zabaan), Aramaic (ܠܫܢܐ/לשנא lišānā), Hungarian (nyelv), Hebrew (לָשׁוֹן lashon), Turkish (dil), and Danish (tunge), 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.

Anatomy

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 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 muscles 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 name

anatomical name

adjective

tongue tip

apex

apical

tongue blade

lamina

laminal

tongue dorsum

dorsum (back)

dorsal

tongue root

radix

radical

tongue body

corpus

corporeal

Muscles of the tongue


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

3/4 view of a 6.5 cm human tongue.

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

Extrinsic muscles


Extrinsic muscles of the tongue by definition originate from structures outside the tongue and insert into the tongue. The four paired extrinsic muscles protrude, retract, depress, and elevate the tongue:

Muscle

From

Nerve

Function

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.

Intrinsic muscles


Coronal section of tongue, showing intrinsic muscles

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.[2]


  • The superior longitudinal muscle runs along the superior surface of the tongue under the mucous membrane, and elevates, assists in retraction of, or deviates the tip of the tongue. It originates near the epiglottis, the hyoid bone, from the median fibrous septum.

  • The inferior longitudinal muscle lines the sides of the tongue, and is joined to the styloglossus muscle.

  • The verticalis muscle is located in the middle of the tongue, and joins the superior and inferior longitudinal muscles.

  • The transversus muscle divides the tongue at the middle, and is attached to the mucous membranes that run along the sides.

The tongue is often cited as the "strongest muscle in the body," a claim that does not correspond to any conventional definition of strength.

Papillae and taste buds


See also: Taste bud

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



  • filiform (thread-shape)

  • fungiform (mushroom-shape)

  • circumvallate (ringed-circle)

  • foliate (leaf-shape)

All papillae except the filiform have taste buds on their surface.

Close-up view of a tongue with visible fungiform papillae (large bumps) scattered among filiform papillae (small bumps).

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 Tongue-tie (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 savory. 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 of the tongue


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 pharyngeal branch of vagus nerve (cranial nerve X).

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

  • For the anterior two-thirds of the tongue, general sensations and taste sensations are carried via different nerves.

    • Somatic sensations travel from the tongue via the lingual nerve, a major branch of the mandibular nerve (itself a branch of the trigeminal nerve). This nerve also carries general sensation from areas of the oral mucosa and gingiva of the lower teeth.

    • Taste sensation is carried to the facial nerve via the chorda tympani. The chorda tympani also carries parasympathetic fibers from the facial nerve to the submandibular ganglion.

  • The posterior one-third of the tounge has a more simple innervation, as both taste and general sensations are carried by the glossopharyngeal nerve.

Vasculature of the tongue


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.



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


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