Innervation
The innervation (supply of nerves) of the tongue is quite complicated because it consists of three different parts, namely a motor, a sensitive and a sensory (responsible for taste) part. The motor innervation of the tongue muscles takes place via the 12th cranial nerve, the hypoglossal nerve. Sensory and sensory innervation differ depending on the location on the tongue:
- The posterior third (up to the sulcus terminalis) is sensitively supplied by the 9th cranial nerve, the nervus glossopharyngeus,
- Whereas the front two thirds are supplied by the lingual nerve, which is a branch of the 5th cranial nerve (trigeminal nerve).
- The sensory innervation is also ensured by the nervus glossopharyngeus in the posterior third,
- In the anterior two-thirds, the chorda tympani (a branch of the 7th cranial nerve, the facial nerve) is responsible for sensory innervation, which is attached to the lingual nerve.
Tongue mucosa
On the upper side of the mucosa, which covers the tongue all around, a multi-layered, unkeratinized squamous epithelium is found, in which four different types of papillae can be found, which can be divided into two groups:
- On the one hand there are the mechanical papillae (Papillae filiformes). These are thread-like and are mainly responsible for the specific surface condition of the tongue. They give the tongue its tactile sensation.
- On the other hand, there are the gustatory papillae (Papillae gustatoriae), which are divided into three subgroups according to their shape: the fungal papillae (Papillae fungiformes), the leaf papillae (Papillae foliatae) and the wallpapillae (Papillae vallatae). All three types are connected to the taste buds and contain taste buds, small organs that represent the nerve endings and enable us to taste. In addition, the tongue also contains a few small salivary glands, which are more commonly found in the area of the root of the tongue.
Functions of the tongue
The tongue fulfills a number of important functions in humans. On the one hand, it is the first point of contact during food intake. It moves the food in the mouth, distributes it in such a way that it can reach the teeth, crushes and crushes it partially and mixes it with the saliva, which already initiates the digestion of certain food components.
Finally, it pushes the chyme into the throat, which plays a decisive role in the swallowing process. Also for speaking, the tongue is absolutely necessary, since it is involved in the articulation of the so-called tongue-lutes. The palate or soft palate does not play the last role in this process.
In addition, the tongue is the organ that makes tasting possible. On it lie a multitude of taste buds that enable us to distinguish between sweet, sour, salty, bitter and umami (tasty, fleshy) tastes. The buds for the quality “sweet” are more in the front part of the tongue, followed by salty, sour and then salty again.
The sensation “bitter” is perceived mainly in the rear part of the tongue. In principle, however, contrary to the long-held opinion, any quality of taste can be perceived with any part of the tongue. Changes in the tongue can often be an indication of illness, which is why an examination of the tongue is an essential part of a general physical examination.
This examination involves looking at the surface of the tongue (often using a tongue spatula to assess the entire surface back to the root of the tongue), particularly to check for any The tongue itself can be the site of disease. For example, there is fungal infection of the tongue with candida, aphthae, abscesses and even tumors that affect only the tongue. On the other hand, it can also be affected by an underlying disease.
Here only some frequently observed examples shall be mentioned: The varnished tongue is an unusually smooth and sometimes slightly darker tongue, which indicates the presence of liver cirrhosis or a certain form of anaemia, pernicious anaemia. A raspberry tongue, which is conspicuous by its strong reddish color and berry-like surface, is found in some febrile infections, but especially in scarlet fever. The blue coloration of the tongue indicates a central lack of oxygen.
An increased whitish coating on the tongue often also indicates an infection or simply that no food has been consumed for a long time, which is why the coating can accumulate more easily.
Aphtae are erosions of mucous membranes that can occur on the tongue. This also includes small, painful wounds on the tongue, which can be covered with a white-yellowish coating, the so-called fibrin.
In the area surrounding the aphtae, additional inflammatory reactions take place, which contribute to the fact that patients suffering from aphtae have strong pain. Patients are severely restricted in their quality of life, because not only eating but also speaking and swallowing are extremely painful.Infants and toddlers may stop eating and drinking if they have aphthae on their tongue. The patient’s pain does not depend on the size of the aphtae, but on the localization.
Lesions of the tongue are particularly painful because the tongue is supplied with many nerves and is exposed to strong mechanical stress. In addition, the pain is aggravated when acidic foods and drinks are consumed, which additionally irritate the inflammatory vesicles. The causes for the development of aphthae are not conclusively clarified.
Besides infectious causes, autoimmune processes are also held responsible for the development of aphthae. Often viral infections, such as an infection with the herpes virus, are responsible for the development of aphthae. Aphthae on the tongue can also be caused by digestive problems or immunodeficiency.
Besides these factors, food is also held responsible for the development of aphthae. In addition to acidic foods, nuts or tomatoes should also play a role. Furthermore, it is assumed that deficiencies of vitamin B12, iron or folic acid can lead to the development of aphthae.
A drug therapy is usually not necessary, since the aphthae heal on their own after some time. Since there are also no direct remedies against aphthae, painkillers are mainly used to relieve the pain. If bacteria are suspected to be the cause of aphthae, antibiotics are prescribed. To disinfect the oral cavity, solutions of hydrogen peroxide or simple household remedies such as camomile and sage tea can be used to rinse the mouth.
