The anus is the end part of the intestine through which the body ejects feces (that is, the remnants of waste food).
The structure of the human anus
The anus is limited by sphincters, which are formed by muscles. Such muscular rings are necessary to control the opening and closing of the anus. There are two anorectal sphincters in the human body:
- Internal, consisting of thickening of the smooth muscles of the rectum and not subject to consciousness. Its length is from one and a half to three and a half centimeters.
- External, composed of striated muscles and controlled by the mind. Its length varies from two and a half to five centimeters.
The anus ends with the anal edge, which is a sharp transition of the scaly mucous lining of the distal anorectal canal into the skin covering of the perineum. The skin around the anus tends to be more pigmented (i.e. darker in color) and wrinkled due to the presence of the external sphincter.
In childhood, the anus is located more dorsally than in adults, about twenty millimeters from the coccyx. The diameter of the anus is usually three to sixcentimeters, and the length of the channel varies from three to five centimeters. In addition to sphincters, the rectal obturator apparatus includes muscles that lift the anus and muscles of the pelvic diaphragm.
In the structure of the anus, three sections can be distinguished:
- The mucosa in this section is provided with longitudinal folds, between which crypts (anal sinuses) are found, where the openings of the anal glands go.
- Area covered by squamous stratified epithelium.
- This section is covered with stratified keratinized squamous epithelium and is supplied with numerous sebaceous and sweat glands, as well as hair.
The area of the anus and rectum has a developed circulatory network, as well as many nerve endings, which allows you to deliberately delay the act of defecation and is often the cause of neurogenic constipation.
Anus topography
The structures that interact directly with the anal canal are the rectal ampulla and the sigmoid colon. The anal canal is located in the perineum. In front, the rectum is adjacent to the seminal vesicles, ampullae of the vas deferens, the bladder and the prostate gland in men. In women, the vagina and uterus are located in front. The canal ends with an anus. Posteriorly, the external sphincter is attached to the coccyx by means of the analococcygeal ligament.
In the area of the perineum, behind and on the sides of the anus, there are paired ischiorectal fossae, shaped like a prism and filled with fatty tissue, in whichnerves and blood vessels pass through. In the frontal section, the pits have the shape of triangles. The lateral wall of the fossa is formed by the obturator muscle and ischial tuberosity (inner surface), the medial wall is formed by the external sphincter and the muscle that raises the anus. The posterior wall of the fossa is formed by the coccygeal muscle and its posterior bundles, which raises the anus, and the anterior wall is formed by the transverse muscles of the perineum. Adipose tissue, which is located in the cavity of the ischiorectal fossa, performs the function of an elastic elastic pillow.
The structure of the female anus
In the female body, the rectum is adjacent to the vagina in front and is separated from the latter by a thin layer of Denovillier-Salishchev. Due to this structural feature of the anus and rectum in women, both infectious and tumor agents easily penetrate from one cavity to another, which leads to the formation of rectovaginal fistulas as a result of various injuries or perineal ruptures during childbirth.
The structure of the anus in women determines its shape in the form of a flat or slightly protruding formation. This is attributed to the fact that in the process of delivery, the muscles of the perineum relax, and the muscles that lift the anus lose their ability to contract.
Features of the anus in men
The structure of the male anus has some differences. In men (especially muscular men) the anus looks like a funnel. The anterior wall of the anal canal is adjacent to the bulb of the urethra and the apex of the prostateglands. In addition, the internal sphincter of men is thicker than that of women.
Functions of the anus and rectum
The rectum is responsible for removing waste materials from the body. In addition, it absorbs liquid. So, with dehydration and pressing of feces, about four liters of fluid per day returns to the body. Together with the liquid, microelements are reabsorbed. The rectal ampulla is a reservoir for feces, the accumulation of which leads to overstretching of the intestinal walls, the formation of a nerve impulse and, as a result, the urge to defecate (defecation).
And now about the functions of the anus. Being in constant tension, its sphincters control the release of feces (defecation) and the release of gases from the intestines (flatulence).
Pathologies of the anus
- Tumours.
- Hemorrhoids.
- Hernias.
- Various mucosal defects (cysts, anal fissures, ulcers).
- Inflammatory processes (abscesses, paraproctitis, proctitis, fistulas).
- Congenital conditions (anus atresia).
Sphincter spasm
In accordance with the structure of the anus, the manifestations of pathologies of this part of the intestine are also characteristic. Among the symptoms, the most common sphincter spasm (external or internal), which is pain and discomfort in the anus.
The causes of this condition are:
- mental problems;
- prolonged constipation;
- chronic inflammation in the area of internal or externalsphincter;
- excessive innervation.
According to the duration, allocate:
- Prolonged spasm, characterized by severe pain, which is not removed by taking ordinary analgesics.
- Transient spasm - sharp short-term acute pain in the anus, radiating to the pelvic joints or coccyx.
Depending on the cause, the spasm can be:
- primary (due to neurological problems);
- secondary (due to problems in the gut itself).
Manifestations of this symptom are:
- appearance of pain due to stress;
- pain during defecation is stopped or with warm water;
- the pain is acute, localized in the anus and radiates to the coccyx, pelvis (perineum) or abdomen.
Diagnosis of pathological processes
- Computed tomography can detect polyps and other pathological formations.
- Biopsy is used to determine the malignancy of tumor processes.
- Anoscopy (rectomanoscopy) is used to assess the condition of the anus mucosa, as well as taking material for a biopsy.
- Anorectal manometry. In accordance with the structure of the anus (see photo above), the muscular apparatus (sphincters) of the anus is diagnosed. Most of the time, the anal muscles are at maximum tension to control defecation and flatulence. Up to eighty-five percent of the basal anal tone is carried out by the internal anal sphincter. With insufficientor lack of coordination between the muscles of the pelvic floor and the sphincters of the anus, dyschezia develops, which is manifested by difficult defecation and constipation.
- Rectal examination. This method allows you to identify hernias, prolapse of the intestines, uterus, hemorrhoids, fistulas, cracks and other pathologies of the anus and rectum.
- Anus ultrasound. Based on this study, it is possible to assume the presence of neoplasms, determine their location and size, detect hemorrhoids, and so on.
Anorectal discomfort
The anatomical structure of the anus is such that the skin in this area is especially sensitive, and pathogenic bacteria can settle in its folds if hygiene is not followed, frequent constipation or diarrhea, resulting in discomfort, irritation, itching, unpleasant odor and pain.
To reduce these manifestations and prevent them, you should:
- Wash the anus and the skin around it with water without soap (the latter can dry out the skin and, as a result, lead to even more discomfort). Preference should be given to spray "Kavilon" or the use of alcohol-free wet wipes (since toilet paper irritates the skin).
- The skin around the anus should be dry.
- It is necessary to create a barrier to moisture penetration. For example, the use of Dimethicone cream is recommended, which creates a protective film on the skin around the anus.
- Using pharmacy powders (such as talc or cornstarch). Applythey should be applied to pre-cleansed and dried skin.
- Using disposable underwear or absorbent pads.
- The use of "breathable" underwear and clothes made of natural materials, free cut, which does not restrict movement.
- In case of fecal incontinence, change underwear immediately.
Treatment
The purpose of this or that therapy depends on the nature of the disease. With spasms of sphincters, first of all, the causes that caused them are eliminated. In addition, laxatives, antibacterials, painkillers and antispasmodics in the form of ointments / suppositories, as well as physiotherapy, electrosleep, applications, massage, microclysters are prescribed. If the conservative treatment is ineffective, surgical operations are performed.
Hemorrhoids are treated with special suppositories and ointments, as well as surgical methods. Congenital pathologies (anus atresia) require immediate surgery. Tumors of the anus are treated with a combination of radiation and chemotherapy, as well as surgical removal of the tumor. Cracks in the anus are perfectly treatable with the use of special baths, diet, healing suppositories and creams, as well as surgery. Hernias and prolapses of the rectum are eliminated by surgical methods.
