Anus, intestinal outlet As a continence organ, the anus assumes an important function in mammals. Only through smooth communication between the brain and the various muscles of the anus can defecation be controlled in a targeted manner. However, this communication can be disturbed, especially in older people or small children.

Furthermore, diseases of the anal canal often lead to the fact that the stool can no longer be held deliberately. For the persons affected, this condition results in an enormous amount of suffering, which can severely restrict their everyday life. For this reason, people who notice problems with bowel movement should consult a specialist at an early stage. After extensive diagnostics, the doctor can initiate appropriate treatment.


The anus is basically a simple opening of the intestinal canal. Through the anus, undigested food components can leave the gastrointestinal tract. Due to the fact that the anus is a continuation of the colon, it can be assumed that the anatomical structure of both structures is similar.

The end section of the gastrointestinal tract has two important muscles that are arranged in a ring around the anus. Both muscles are controlled by different parts of the nervous system. While the inner ring muscle of the anus (Musculus sphincter ani internus) is supplied by involuntary nerve fibres, the outer sphincter muscle (Musculus sphincter ani externus) is connected to involuntary nerves.

Because of this innervation, the inner sphincter cannot be controlled by the patient’s own will. The external sphincter of the anus, on the other hand, can be opened or closed in a controlled manner. The actual task of these two muscles is the regulation of bowel movement.

Together with the so-called Musculus levator ani, the inner and outer muscle of the anus form the closing apparatus of the rectum. In addition, the sphincter muscles model the end section of the gastrointestinal tract and thus form the anal canal. This canal can assume a length of approximately two to four centimetres in adults.

Common diseases of the anus

The anus itself represents one of the most sensitive structures of the gastrointestinal tract. For this reason, a variety of diseases can lead to irregularities in the emptying of the bowels. Among the most important diseases of the anus are

  • Mariscs
  • Hemorrhoids
  • Anal fissure
  • Anal Carcinoma
  • Perianal thrombosis
  • Perianal abscess
  • Perianal Fistula

Mariscs are flaccid skin folds that are located in the area of the anus.

In most cases, patients who have mariscs do not experience any discomfort. For this reason, the presence of these anal skin folds is considered rather unproblematic. Complaints usually only occur if anal hygiene is neglected.

The reason for this is the fact that bacterial pathogens and fungi settle and multiply particularly quickly in the skin folds and can thus cause infections. The affected patients then typically experience severe itching and pain in the anal region. Clinically, the anus of the affected person is reddened and swollen.

While asymptomatic mariscs do not require treatment, anal skin folds that cause itching and/or burning should be treated surgically as a matter of urgency. During the surgical procedure, the marisks can be gently removed with an electric knife and the patient can be left free of symptoms. However, as most patients have a predisposition to the formation of mariscs, a new skin fold may appear after a short time.

For this very reason, optimal anal hygiene should be a priority with mariscs. Haemorrhoids are arterio-venous vascular cushions (i.e. vascular cushions that have both arteries and veins) that protrude from the intestinal canal in the area of the anus. In general, it can be assumed that about 80 percent of the adult population has such vascular cushions.

In most cases, the development of a haemorrhoid is based on stool regulation problems. Above all, excessive pressing during bowel movement is considered a risk factor for the occurrence of haemorrhoids on the anus. The increase in pressure in the abdominal cavity during pregnancy can also promote the development of haemorrhoids.

In addition, weak connective tissue and increased pressure within the anal sphincter muscles can promote the development of haemorrhoids. People who have bulging anal vascular cushions usually suffer from severe itching and pain during bowel movements. In addition, occasional bleeding and the feeling of incomplete defecation are among the most common symptoms of haemorrhoids.

The treatment of haemorrhoids depends mainly on the degree of severity determined during a digital rectal examination. In addition, the symptoms perceived by the affected patient are also of decisive importance. Haemorrhoids that have not yet emerged from the anus (grade I) are usually treated conservatively, i.e. through targeted stool regulation and consultation.

In the case of advanced haemorrhoids that clearly protrude from the anus, more extensive therapy may be necessary. Especially the so-called sclerotherapy is one of the most frequently performed treatment measures. In this procedure, small parts of the haemorrhoids are fixed and then treated with a substance that provokes inflammatory reactions (e.g. polidocanol).

In this way, the vascular cushions close up and the hemorrhoid shrinks. Various creams and ointments that have to be applied to the anus can help against the symptoms caused by the vascular cushions. An anal carcinoma is a rather rare but very malignant tumour of the anus.

Histologically speaking, the anal carcinoma belongs to the so-called squamous cell carcinomas. A rapid metastasis via the lymphatic system is typical for this type of cancer. Affected patients usually notice pain during bowel movements and a pronounced foreign body sensation in the anus at an early stage.

In addition, severe itching, irregularities in the stool and bleeding are among the most common symptoms of anal carcinoma. The treatment of this cancer depends above all on the exact location of the tumour. The complete removal of the altered tissue is considered the goal of any therapeutic strategy.

In the case of small carcinomas, surgical removal of the tumour in healthy individuals can be aimed for. Larger anal carcinomas, on the other hand, usually require a combination of chemo- and radiotherapy. Surgical treatment can only be initiated once the altered tissue on the anus has shrunk.