Tonsils: Structure, Function & Diseases

The tonsils – in technical jargon tonsils – are probably known to everyone. After all, tonsillitis (inflammation of the tonsils) is one of the 20 most common reasons to seek the advice of a doctor. But what these small organs are actually good for, know only the fewest.

What are tonsils?

Anatomy of the pharynx and pharyngeal tonsils. Click to enlarge. Humans by no means have only two tonsils – in fact, a full four types of tonsils exist in the human anatomy:

Pharyngeal tonsil (tonsilla pharyngica), Palatine tonsil (tonsilla palatina), Lingual tonsil (tonsilla lingualis) and Tubal tonsil (tonsilla tubaria). When people speak of tonsils in general, they usually refer to the palatine tonsils (tonsilla palatina). All of these tonsils are part of what is known as Waldeyer’s pharyngeal ring, a system of lymphoid tissue that is entrusted with immune defense tasks.

Anatomy and structure

The various tonsils are located in the oral cavity, nasal cavity, and pharynx. Here, the palatine tonsils are easily visible when swollen and the mouth is open, as they are located directly between the palatine arches. The pharyngeal tonsils, on the other hand, are located at the roof of the pharynx, with a connection to the respiratory tract, the lingual tonsils are located at the base of the tongue, and finally the tubal tonsils are located near the eustachian tube of the inner ear. All tonsils have the structure in common, namely they are a collection of lymph follicles, which are found below the mucosa. The surface is covered with deep indentations. These indentations are called crypts and they are there to increase the surface area of the tonsils. Thus, the surface area of the palatine tonsils when spread out is an incredible 300cm². In the immediate vicinity of the tonsils are usually glands that provide for their flushing and prevent accumulations of various kinds in the crypts.

Function and tasks

Schematic diagram showing the anatomy of the pharynx with enlarged tonsils (adenoid hyperplasia). Click to enlarge. The tonsils are important for the immune system and have a kind of surveillance function at relevant entrances to the body. Thus, they sit right where breath or food enters the body and support the immune defense by analyzing invading structures and detecting bacteria. In this way, other active structures of the immune defense can be prepared to ward off the danger. The nasal airways pass through the pharyngeal tonsil at the roof of the throat, ingested food must pass through the lingual tonsil and the palatine tonsil, and breath coming in through the mouth also falls into the examination area of the palatine tonsil. It is interesting to note that the tonsils are relatively large in children, but lose tissue as they age.

Diseases and complaints

Probably the most common problem that occurs with the tonsils is inflammation of the palatine tonsils (tonsillitis). This can occur both acutely and chronically or recurrently and is triggered either by bacteria or viruses. In this case, there is a clear reddening and swelling of the palatine tonsils, sometimes also with whitish-yellowish fibrin coatings. Inflammation of the palatine tonsils can also occur unilaterally. Depending on the course, trigger and severity, tonsillitis is treated in different ways. In the case of chronic, severe tonsillitis, removal of the palatine tonsils is sometimes advisable. Also as a result of Pfeiffer’s glandular fever, a severe infection with the Epstein-Barr virus and extremely protracted course, the tonsils become inflamed and are completely covered with fibrin coating. In this case, only the pain can be treated with painkillers. Tonsil stones are another extremely unpleasant problem that can occur with the tonsils. These form due to accumulation of food debris, rejected cells and bacteria in the crypts of the palatine and pharyngeal tonsils and can be a cause of severe bad breath. To prevent tonsil stones, the tonsil region can be carefully cleaned with an oral douche. In the case of the pharyngeal tonsil, enlargement leads to ear infections and hearing loss. The proliferation of the tissue is popularly known as a polyp and can be removed by a surgeon. The tubal tonsil can also swell and thus obstruct the pressure equalization of the inner ear. Thus, the symptoms of swollen tubal tonsil are a feeling of pressure on the respective ear and possibly even hearing loss.Because the crypts of the lingual tonsil open into the salivary glands, it is so well flushed that enlargement or inflammation is extremely unlikely.