Anatomical structure of the human anus

The anus is the final part of the intestine through which the body ejects stool (that is, the remains of the used food).

The structure of the human anus

The anal opening is limited to sphincters, which are formed by muscles. Such muscle rings are necessary to control the opening and closing of the anus. In the human body there are two anorectal sphincters:

• Internal, consisting of thickenings of 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, consisting of striated muscles and controlled by consciousness. 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 of the perineum. The skin in the anus is usually more pigmented (i.e., darker in color) and wrinkled due to the presence of an external sphincter.

In childhood, the anus is more dorsally than in adults, about twenty millimeters from the coccyx. The diameter of the anus is usually three to six centimeters, and the length of the canal varies from three to five centimeters. In addition to sphincters, the composition of the rectum obturator includes muscles that lift the anus and the muscles of the pelvic diaphragm.

In the structure of the anus, three departments can be distinguished:

1. Mucous in this department is equipped with longitudinal folds, between which are found crypts (anal sinuses), where the holes of the anal glands come out.
2. Zone covered with a flat multilayer epithelium.
3. This department is covered with multilayer cornified flat epithelium and is provided with numerous sebaceous and sweat glands, as well as hair.

The anal and rectum region has a developed blood network, as well as a variety of nerve endings, which allows you to deliberately delay the act of bowel movement and is often the cause of neurogenic constipation.

Anus Topography

The structures that directly interact 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 attached to the seminal vesicles, ampullas of the vas deferens, bladder and prostate gland in men. In women, the vagina and uterus are located in front. The canal ends in the anus. Behind, the external sphincter is attached to the coccyx by means of an anus-coccyx ligament.

In the perineal region, posterior and lateral sides of the anus are paired sciatic and rectum fossa, shaped like prisms and filled with fatty tissue, in which the nerves and blood vessels pass. In the frontal incision the pits are triangular in shape. The lateral wall of the fossa is formed by the occlusal muscle and the ischial tuberosity (inner surface), the medial - by the external sphincter and muscle, which raises the anus. The posterior wall of the fossa is formed by the coccygeal muscle and its posterior tufts, which raises the anus, and the anterior one - the transverse muscles of the perineum. Fatty tissue, which is located in the cavity of the sciatic and rectum ceca, functions as an elastic elastic cushion.

The structure of the female anus

In the female body, the rectum is in front of the vagina and is separated from the latter by a thin layer of Denovil-Salishchev. Due to this peculiarity of the structure 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 rectal-vaginal fistulas as a result of various injuries or perineal ruptures during childbirth.

The structure of the anus in women causes its shape in the form of a flat or slightly protruding formation. Associate this with the fact that in the process of delivery, the muscles of the perineum relax, and the muscles that lift the anus, lose the ability to contract.

Features of the anus in men

The structure of the male anus has some differences. In men (especially muscular), the anus looks like a funnel. The anterior wall of the anal canal is attached to the bulb of the urethra and the apex of the prostate gland. In addition, the inner sphincter of men is thicker than that of women.

Functions of the anus and rectum

The rectum is responsible for removing the waste material from the body. In addition, it absorbs liquid. So, when dehydrating and pressing the feces back to the body about four liters of fluid per day. Together with the liquid, microelements are absorbed back. The rectal ampulla is a reservoir for feces, the accumulation of which leads to overgrowth of the intestinal walls, the formation of a nerve impulse and, as a consequence, the urge to defecate (defecate).

And now about the functions of the anus. Being in constant tension, his sphincters control the release of stool (defecation) and the escape of gases from the intestine (flutulenia).

Pathology of the anus

• Tumors.
• Hemorrhoids.
• Hernias.
• Various defects of the mucosa (cysts, anal fissures, ulcers).
• Inflammatory processes (abscesses, paraproctitis, proctitis, fistula).
• Congenital conditions (atresia of the anus).

Spasm of sphincters

In accordance with the structure of the anus, the manifestations of the pathology of this part of the intestine are also characteristic. Among the symptoms, the most common spasm of the sphincter (external or internal), which is pain and discomfort in the anus.

The reasons for the appearance of such a state are:

• Mental problems;
• Prolonged constipation;
• Chronic inflammation in the region of the internal or external sphincter;
• Excess innervation.

Accordingly, the duration is:

• A prolonged spasm characterized by severe pain, which is not removed by the use of ordinary analgesics.
• Short-term spasm is a sharp short-term acute pain in the anus giving into the pelvic joints or coccyx.

Depending on the cause, spasm can be:

• Primary (due to neurological problems);
• Secondary (due to problems in the intestine itself).

Manifestations of this symptom are:

• The appearance of pain due to stress;
• Painful sensations are overcome at defecation or with the help of warm water;
• Pain acute, localized in the anus and gives to the coccyx, pelvis (perineum) or abdomen.

Diagnosis of pathological processes

• Computer 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 mucosa of the anus, as well as taking material for biopsy.
• Anorectal manometry. In accordance with the structure of the anus (photo above), the muscular apparatus (sphincter) of the anus is diagnosed. Most of the time, the anal muscles are as tight as possible to control the defecation and flutulenium. Up to eighty-five percent of basal anal tone is performed by an internal anal sphincter. With insufficient or lack of coordination between the muscles of the pelvic floor and the sphincters of the anus, dysceia develops, which is manifested by difficulty in stool and constipation.
• Rectal examination. This method allows you to identify hernias, prolapse of the intestine, uterus, hemorrhoids, fistula, cracks and other pathologies of the anus and rectum.
• Ultrasound of the anus. Based on this study, we can assume the presence of neoplasms, determine their location and size, detect hemorrhoids, and so on.

Discomfort in the anorectal area

The anatomical structure of the anus is such that the skin in this area is particularly sensitive, and in its folds, if hygiene is not observed, frequent constipation or diarrhea, pathogenic bacteria can settle, resulting in discomfort, irritation, itching, unpleasant odor and pain.

To reduce these manifestations and prevent them should be:

• Wash the anus and skin around it with water without soap (the latter can dry the skin and, as a result, lead to even greater discomfort). It is necessary to give preference to the spray "Kavilon" or to use alcohol-free wet wipes (since toilet paper irritates the skin).
• The skin in the anus should be dry.
• It is necessary to create a barrier to moisture penetration. For example, the use of cream "Dimethicone", which creates a protective film on the skin around the anus, is recommended.
• Use of chemist's powders (for example, talc or corn starch). Apply them to the pre-cleaned and dried skin.
• Use disposable underwear or moisture absorbing pads.
• Using "breathable" underwear and clothes from natural materials of a free cut that does not constrain movements.
• In the case of incontinence, immediately replace the underwear.

Treatment

The purpose of this or that therapy depends on the nature of the disease. With spasms sphincters first of all, eliminate the reasons that they were called. In addition, laxative, antibacterial, analgesic and antispasmodic agents in the form of ointments / suppositories are prescribed, as well as physiotherapy, electrosleep, applications, massage, microclysters. If the conservative treatment is ineffective, surgery is performed.

Treatment of hemorrhoids is performed with the help of special candles and ointments, as well as surgical methods. Congenital pathologies (atresia of the anus) need immediate surgery. Tumors of the anus are treated with a combination of radiation and chemotherapy, as well as surgical removal of the neoplasm. Cracks in the anus area are excellent for treatment with special baths, diet, healing candles and creams, and also surgically. Hernias and prolapses of the rectum are eliminated by surgical methods.