home→Diagnostics→ The structure and function of the rectum. Rectum: structure and typical diseases Features of the structure of the rectum

The structure and function of the rectum. Rectum: structure and typical diseases Features of the structure of the rectum

Serving for the formation, accumulation and further removal of feces. The length of the rectum averages 13-16 cm. Its diameter varies throughout, and reaches 16 mm in the widest part.

The rectum is a natural continuation, and originates at the level of the upper edge of the second sacral vertebra. For the most part, it is located in the small pelvis and only a small part (anal canal) belongs to the perineum.

Front rectum Borders with bladder, seminal vesicles, prostate - in men, with the back wall of the cervix and vagina - in women. Behind is the sacrum and coccyx, the space between the intestinal wall and the periosteum is filled with a fat layer. On the sides are the ischiorectal fossae, in which the iliac vessels and ureters pass.

In the sagittal plane, the rectum has an S-shape, and, as it were, repeats the course of the sacrum and coccyx. The upper bend is turned back and corresponds to the concavity of the sacrum, subsequently the direction of the intestine changes to the opposite, and a second bend is formed at the coccyx, facing the convexity forward. Further, the intestine goes back and down, continuing into the anus, and ends with the anus.

Structure

Sections of the rectum

The rectum has 3 sections:

Rectosigmoid (supraampular);
Ampoule - upper ampulla, middle ampulla, lower ampulla;
Anal canal.

Rectosigmoid department- this is a small area in length, which is a transition zone between the sigmoid colon and the ampulla of the rectum. Its length is 2-3 cm, and its diameter is about 4 cm. At this level, the peritoneum covers the intestines from all sides, forming a short triangular one, which then quickly disappears. Muscle fibers, unlike the overlying sections, are distributed evenly around the circumference, and are not collected in ribbons. The direction of the course of the vessels also changes from transverse to longitudinal.

Ampoule- the longest and widest part of the rectum. Its length is 8-10 cm, and the diameter in a healthy person is about 8-16 cm, with a decrease in tone it can reach 40 cm.

In the upper ampullar region, the peritoneum covers the intestine from three sides - in front and from the sides, from top to bottom, the peritoneal cover gradually disappears, passing to the uterus (in women) or bladder (in men), as well as to the side walls of the pelvis. Thus, the lower sections of the rectum are located extraperitoneally, only a small section of the anterior wall of the intestine is covered by the peritoneum.

anal canal- the transition zone between the intestine itself and the anus. The canal is about 2-3 cm long and is surrounded by muscular sphincters. In the normal state, due to the tonic contraction of the internal sphincter, the anal canal is tightly closed.

The structure of the wall of the rectum

Mucous membrane.

The inner lining in the upper sections is represented by a single-layered transitional epithelium, in the lower sections - by stratified squamous. The mucous membrane forms 3-7 transverse folds with a helical course, as well as numerous non-permanent longitudinal folds, which are easily smoothed out. In the anal canal there are 8-10 permanent longitudinal folds - Morgagni's columns, between which recesses are formed - the anal sinuses.

submucosal layer.

The submucosa in the rectum is highly developed, which ensures the mobility of the mucosa and contributes to the formation of folds. Vessels and nerves pass through the submucosal layer.

Muscular sheath.

The muscular layer has 2 layers: circular (inside) and longitudinal (outside).

In the upper part of the anal canal, the circular layer thickens sharply and forms the internal sphincter. Outside of it and somewhat distal is the external sphincter, formed by striated muscle fibers.

The longitudinal muscles are distributed evenly in the walls of the intestine and are intertwined below with the external sphincter and the levator muscle. anus.

Functions

The rectum performs the following functions:

Reservoir and evacuation. The rectum serves as a reservoir for the accumulation of feces. Stretching of the rectal ampulla with feces and gases causes irritation of the interoreceptors located in its wall. From the receptors, impulses travel through sensory nerve fibers to the brain, and then through the motor pathways they are transmitted to the muscles of the pelvic floor, abdominals and smooth muscles of the rectum, causing their contraction. The sphincters, on the contrary, relax, due to which the intestines are released from the contents.
Hold function. In the passive state, the internal sphincter is contracted and the anal canal is closed, so that the contents are kept inside the intestine. After the urge to defecate occurs, the smooth muscles of the intestine contract and the internal sphincter relaxes involuntarily. The external sphincter is arbitrary, that is, its contraction is subject to volitional effort. Thus, a person can independently regulate.
. In the rectum, water, alcohol and some other substances, including medicinal ones, are absorbed. The function of absorption is important in medicine, allowing the use of rectal forms of drugs.

Methods for examining the rectum

Finger research is a mandatory method for examining the rectum, which is performed before any other instrumental method. Before starting a digital examination, palpation of the abdomen is performed, a gynecological examination is performed in women, and the condition of the perianal region is assessed.

To conduct an examination, the patient takes a knee-elbow position, the doctor treats a gloved finger with petroleum jelly and inserts it into the anus. Depending on the purpose of the study and the suspected pathology, the position of the patient may change.

This examination allows you to assess the tone of the sphincter, the condition of the mucous membrane of the rectum, perirectal tissue and lymph nodes located in it. In men, with the help of a digital examination, the condition of the prostate gland can be assessed.

Sigmoidoscopy allows you to visually assess the condition of the mucous membrane of the rectum and partially sigmoid, its color, the severity of the vascular pattern, the presence of various defects and neoplasms, determine the width of the intestinal lumen at its different levels, folding, mobility of the mucous layer, identify the source of bleeding. The examination is carried out using a special device - a sigmoidoscope.

This method resembles sigmoidoscopy, but is more specialized and is used for targeted examination of the anal canal. in the diagnosis of diseases of the rectum and sigmoid divisions bowel anoscopy is uninformative.

A high-tech method using a device based on flexible light fiber, which allows you to explore the entire large intestine.

Due to the high resolution of the equipment, colonoscopy allows you to detect diseases at the earliest stages, perform a multiple one, and remove polyps.

X-ray examination method. To conduct it, a contrast agent is injected into the rectum using an enema, and then x-rays are taken. Indications for this method are neoplasms of the large intestine.

Rectal cancer- a malignant tumor that forms in the mucous membrane of the final section of the large intestine. Often among doctors the term "colorectal cancer" is used, which includes all tumors of the large intestine, including the rectum.

Among all tumors of the gastrointestinal tract, rectal cancer accounts for 45%.
5% of patients oncological diseases suffer from this tumor.

In Russia, the prevalence of rectal cancer is constantly increasing. The highest frequency is noted in St. Petersburg and the Leningrad region, in Pskov. More than 50,000 new cases of this tumor are detected in our country every year. Between the ages of 30 and 50, the incidence of rectal cancer in last years slightly decreased, while in older people it is constantly increasing.

World statistics

Most often, residents of developed industrial countries, large cities get sick. In the first place - the USA, Canada, Japan. In India and China, the prevalence of pathology is on average 15 times lower. Every year in the world, rectal cancer is diagnosed in 600,000 patients.

The death rate from colorectal cancer is on the rise. Every 10 years it increases by 15% - 20%. Often the disease is detected at a later stage, when many methods of treatment are ineffective.

Survival statistics for patients with rectal cancer:

In developed countries, about 60% of patients survive within 5 years from the moment of detection of pathology.

In developing countries, this figure is no more than 40%.

The most optimistic forecasts for rectal cancer are noted in countries with a high level of medical development: Israel, Germany, the USA.

Anatomy of the rectum

Rectum- This is the end section of the intestine. It ends with an anus, designed to remove feces to the outside. Its length in an adult is from 15 to 20 cm. The main wide part of the rectum - the ampulla - is located in the pelvic cavity and is surrounded by adipose tissue. The final short segment - the anal canal, or anus - is located in the pelvic floor (muscles and soft tissues that limit the pelvis from below) and is surrounded by the sphincter muscle (compressor).

In the mucous membrane of the rectum there are a large number of cells that secrete mucus. It acts as a lubricant during the passage of stool. The mucous membrane is collected in folds, having the form of vertical pillars and a semilunar shape.

In the lower part, the rectum is surrounded on the outside by a hemorrhoidal plexus, consisting of a large number of wide veins.

Causes of colorectal cancer

Factors contributing to the development of malignant tumors of the rectum:

Nutrition Features. Colon cancer is much more common in people who consume large amounts of meat, especially beef and pork. Meat food, getting into the intestines, stimulates the multiplication of bacteria that produce carcinogens. A decrease in plant fiber in the diet also increases the risk of developing pathology.
Hypovitaminosis. Vitamins A, C and E inactivate carcinogens that enter the intestine. With their lack in food, the harmful effects on the wall of the rectum and the entire large intestine are intensified.
Overweight. It has been proven that rectal cancer is most common among obese people.
Sedentary lifestyle. With constant sedentary work, blood stagnation occurs in the veins of the pelvis and hemorrhoids. This leads to dysfunction of the rectal mucosa and increases the likelihood of developing malignant tumors.
Heavy smoking. Statistical studies show that smokers have this type of malignant tumor more often than non-smokers. Apparently, this is due to the effect of nicotine on blood vessels.
Alcohol abuse. Ethyl alcohol has an irritating effect on the intestinal wall, damages the mucous membrane, and promotes the formation of cancer cells.
Occupational hazards. Colon cancer is common among workers exposed to indole, skatole and other harmful substances. Malignant tumors of the large intestine are common among workers in cement factories and sawmills.
Heredity. A person whose relatives suffered from this disease has an increased risk. They are the higher, the closer the degree of relationship.

Precancerous diseases that most often cause malignant tumors of the rectum:

polyps. These are benign formations of the mucous membrane, which are elevations. The risk of malignancy is especially high if the polyp is larger than 1 cm.

Diffuse polyposis- a hereditary family disease in which a large number of polyps form in the rectum and colon.

Papillomavirus infection in the anus papillomaviruses are capable of causing cell mutations leading to the development of malignant tumors.

The degree of risk (%) of developing rectal cancer with polyps of different sizes (source: "Oncology" edited by Academician of the Russian Academy of Medical Sciences V.I. Chissov, Prof. S.L. Daryalova, Moscow, GEOTAR-Media publishing group, 2007 ) :

To date, the mechanism of development of rectal cancer is not well understood.

Symptoms of colorectal cancer

Factors that affect the symptoms of colorectal cancer:

tumor size
duration of the disease
location of the tumor
the nature of the growth of a malignant neoplasm

Symptom	Description
Discharge of blood from the anus.	the most common symptom of rectal cancer, occurs in 70% - 95% of patients most often a small amount of blood is excreted, in the form of streaks in the feces, dark clots blood is excreted either before the stool is passed (usually in drops), or is mixed with it since the blood is released in a small amount, anemia occurs only in the later stages of the disease The reason for the development of the symptom is trauma to the mucous membrane at the location of the tumor during the passage of feces.
Discharge from the rectum of pus and mucus.	late symptom, joins bleeding with a long course of the disease the release of pus is associated with tumor complications: inflammation of the rectal mucosa, the decay of a malignant neoplasm.
Bowel disorders	regular constipation gas and fecal incontinence painful urge to defecate up to 10 - 16 times a day bloating and rumbling of the abdomen - usually in the later stages of the disease These symptoms are caused by a malfunction of the mucous membrane of the rectum and its muscular wall. At first they occur intermittently, then gradually become permanent. Intestinal disorders in rectal cancer are the second most common after bleeding.
Intestinal obstruction	occurs in the later stages of the disease caused by complete occlusion of the rectal lumen by the tumor there is a stool delay of more than 3 - 5 days The patient is experiencing cramping abdominal pain occasional vomiting occurs
Pain in the rectum	if the lower part of the rectum is affected with the capture of the sphincter muscle, then pain occurs in the early stages of the tumor with damage to the upper part of the body pain arise and intensify as the tumor grows into neighboring organs a patient with pain syndrome tries to sit on hard surfaces on only one buttock - doctors call this the “stool symptom”.
Violation of the general condition	general weakness, lethargy, drowsiness fatigue emaciation, sudden weight loss anemia, pale skin At the beginning of the disease, these symptoms are almost invisible. Gradually, they grow and reach apogee, when the tumor is large and is accompanied by multiple metastases.

Diagnosis of rectal cancer

Patient Interview

Points that the doctor should find out during the interview of the patient:

existing complaints and the time of their occurrence;

the nature of nutrition, bad habits;

history: has the patient ever been diagnosed with polyps or other precancerous diseases, has he already been treated for tumors of the rectum or other organs?

family history: have relatives suffered from rectal cancer and other precancerous conditions?

place of work: does the patient have to come into contact with harmful substances?

Finger examination and examination of the rectum in rectal mirrors

Finger examination- the simplest method by which a proctologist (specialist in diseases of the rectum) can identify pathological volumetric formations in the rectum. The doctor asks the patient to stand in a knee-elbow position (on all fours, leaning on the couch with his knees and elbows), puts on latex gloves, lubricates his index finger with petroleum jelly and inserts it into the rectum. The state of its wall and the presence of pathological formations are assessed by touch.

After a digital rectal examination, it is impossible to establish a diagnosis of a malignant tumor. But if any formation is detected, the doctor is obliged to prescribe a further examination to confirm or refute cancer.

A rectal speculum is an instrument that consists of two flaps and two handles. Inspection is also carried out in the knee-elbow position. The doctor inserts a mirror into the anus, while its flaps are in the closed position. By pressing the handles, the proctologist carefully pushes the valves apart, making the intestinal lumen accessible for inspection. After examination with a rectal speculum, it is more likely to assume the presence of rectal cancer, but the final diagnosis must be confirmed by other, more informative, methods.

Instrumental research methods

Research method	Description
Sigmoidoscopy	Endoscopy. Executed using sigmoidoscope- a device consisting of a tube with a lighting device and a device for pumping air. How is the research done? Before conducting sigmoidoscopy, the patient is asked to take one of two positions: knee-elbow: on all fours, leaning elbows and knees on the couch; on the left side with legs bent and pulled up to the stomach: the patient is asked to take a deep breath and then exhale, relaxing the right shoulder and neck, after which the proctoscope is inserted. The doctor inserts a proctoscope into the anus, pumps some air into the rectum to widen its lumen, and examines its mucous membrane. What can be found during recoromanoscopy? polyps and malignant neoplasms on the surface of the mucous membrane; erosion, ulcers and other defects; areas where bleeding is noted; blood, pus in the lumen of the rectum; during sigmoidoscopy, you can take a small piece of the intestinal mucosa for examination under a microscope (biopsy - see below).
Irrigography – radiopaque examination of the rectum and colon	Irrigography- x-rays of the rectum, performed after a contrast agent (suspension of barium sulfate) has been introduced into it. Irrigoscopy- X-ray examination, in which the rectum filled with contrast is examined in real time on the screen. Preparation for the study: at the time of irrigoscopy, the intestines must be completely cleaned; 1 - 2 days before the study, a plentiful drink of water is prescribed; vegetables and fruits, milk, black bread are excluded from the patient's diet; On the eve of doing a cleansing enema. Irrigography: the doctor injects the patient into the rectum with a suspension of barium sulfate using an enema; pictures will be taken in different projections; after emptying the rectum, there is still a little contrast on its walls - you can take additional pictures and examine the relief. What is revealed during irrigography: volumetric formations on the wall of the rectum: the contrast flows around them, the so-called "filling defect" is formed; the size and extent of education; the presence of ulcerative defects on the wall; the nature of tumor growth: outward or inward, into the intestinal wall.
Ultrasound procedure(ultrasound)	What helps to detect ultrasound in rectal cancer: spread of the tumor to neighboring organs; the presence of metastases in adjacent lymph nodes.
CT scan	Most often, computed tomography for rectal cancer is prescribed if, after ultrasound and x-rays, conflicting data are obtained. During computed tomography, images are obtained, which are layered sections of the pelvic region. The rectum and neighboring organs are clearly visible on them.
Additional instrumental research methods for detecting rectal cancer metastases
Survey radiography of the abdominal cavity.	X-rays of the abdomen are taken without the introduction of contrast. The study allows you to assess the condition of the intestine, to identify intestinal obstruction.
Fibrocolonoscopy	An examination in which a long, thin endoscope is inserted through the rectum into the overlying large intestine. Fibrocolonoscopy reveals the spread of a malignant tumor to the wall of the sigmoid and colon, the presence of polyps capable of malignant degeneration.
Radioisotope liver scan	Colon cancer often metastasizes to the liver. If a lesion is suspected, a radioisotope scan is performed. The patient is injected intravenously with isotopes that are captured and accumulated by tumor cells. Then the pictures are taken.
Laparoscopy	An endoscopic examination in which miniature video cameras are inserted into the abdominal cavity through punctures in the abdominal wall. The study is equivalent to surgery and is performed under general anesthesia. Laparoscopy makes it possible for all internal organs to assess their condition and the degree of metastases. The doctor has the opportunity to take material for examination under a microscope (biopsy).
Intravenous urography	X-ray contrast study, in which a solution of a contrast agent is injected intravenously. It is present for some time in the blood, and then excreted through the kidneys, ureters and bladder, staining them. On the pictures you can assess the condition of these organs, the presence of metastases in them.

Laboratory research methods for rectal cancer

tumor markers

Tumor markers are specific substances, the content of which in the blood increases with different types malignant tumors. For the study, blood is taken from a vein for analysis.

Tumor markers specific for colorectal cancer:

SA 19-9- a substance that is secreted by tumor cells of the colon and rectum. Helps to identify not only the tumor itself, but also metastases on early stage.

Cancer embryonic antigen. This substance is produced in the digestive system of embryos and fetuses. In healthy adults, it is practically not detected in the blood. Its level increases with malignant tumors of the intestine.

Determination of tumor markers in the blood is important only as part of a comprehensive examination. By itself, performed in isolation, it does not allow an accurate diagnosis of rectal cancer.

Biopsy

Biopsy- one of the most accurate methods for diagnosing rectal cancer. It allows you to reliably establish the diagnosis and distinguish a malignant tumor from a benign neoplasm. To conduct the study, the doctor takes a small fragment of the tumor during sigmoidoscopy. The procedure is usually completely painless for the patient.

The material obtained during the biopsy may be subject to histological and cytological examination.

Procedures during which material from the rectum and adjacent organs may be taken for biopsy:

sigmoidoscopy;
surgery for rectal cancer;

Histological examination

During histological examination a sample of rectal tissue is viewed under a microscope.
Types of histological examination of rectal tissues:

Urgent. It is performed within 30 - 40 minutes. It is carried out if the result is needed quickly, especially in hospitals. The material is frozen, processed with special dyes, after which it can be studied under a microscope.

Planned. Takes from 5 days. The tissue obtained during recoromanoscopy is treated with a special solution and paraffin, and stained. This is a more complex process than freezing, but it produces more accurate results.

Usually, for greater reliability of the conclusion, the material is examined under a microscope by two or more specialists.

Cytological examination

Cytological examination is the study of the structure of cells, the identification of their malignant degeneration. Unlike histological examination, cytology examines under a microscope not a tissue section, but individual cells.

Materials for cytological research:

a piece of rectal tissue obtained during a biopsy;
pus, mucus from the lumen of the rectum;
imprints of the mucous membrane of the rectum.

Types of colorectal cancer

Classification of malignant tumors of the rectum depending on the cellular structure

The symptoms of colorectal cancer have little to do with histological structure of the tumor(the type of cells that make up its composition and tissue structure). This factor determines the behavior of the tumor, the rate and nature of its growth, affects the specifics of treatment and prognosis.

Types of tumors of the rectum depending on the histological structure:

Adenocarcinoma. The most common type of malignant tumors of the rectum. Revealed in 75% - 80%. It is formed from glandular tissue, most often occurs in people over 50 years of age. When examined under a microscope, it is possible to reveal the degree of differentiation of the tumor tissue. There are highly differentiated, moderately differentiated, poorly differentiated and undifferentiated tumors. The lower the degree of differentiation, the more malignant the tumor, the worse the prognosis for the patient.

Signet cell carcinoma. Occurs in 3% - 4% of cases. It got its name from the characteristic appearance tumor cells under a microscope: in the center of the cell there is a lumen, and on the periphery there is a narrow rim with a cell nucleus - it resembles a ring with a stone. This type of rectal cancer has an unfavorable course, many patients die within the first three years.

Solid rectal cancer. Occurs rarely. It comes from glandular tissue. It consists of poorly differentiated cells, which no longer look like glandular cells and are arranged in the form of layers.

sciros cancer (scir)- also a rare type of malignant tumor of the rectum. It has relatively few cells and a relatively large amount of intercellular substance.

Squamous cell carcinoma. The third most common (after adenocarcinoma and ring cell cancer) malignant tumor of the rectum - is 2% - 5% of the total. This type of tumor is prone to early metastasis. Often its occurrence is associated with human papillomavirus infection. It occurs almost exclusively in the lower part of the rectum, in the region of the anal canal.

Melanoma. A tumor of pigment cells - melanocytes. Located in the anal canal. prone to metastasis.

Classification of rectal cancer depending on the nature of growth

Exophytic cancer. The tumor grows outward, into the lumen of the rectum.

Endophytic cancer. The tumor grows inward, grows into the wall of the rectum.

mixed form. It is characterized by both exophytic and endophytic growth.

Classification of rectal cancer according to the TNM system

This classification is the main one. The stage of the TNM tumor must be indicated in the patient's medical record after diagnosis.

Abbreviation decoding:

T is the size of the tumor (tumor);
N - metastases in nearby lymph nodes (nodus);
M - distant metastases in various organs (metastasis).

Designation	Description
Tx	The size of the tumor is not specified, there are no necessary data.
T0	The tumor was not found.
T is	tumor in situ small sizes, does not grow into the wall of the organ.
T1	Tumor up to 2 cm.
T2	The tumor is 2–5 cm in size.
T3	Tumor larger than 5 cm.
T 4	A tumor of any size that grows into neighboring organs: the bladder, uterus and vagina, the prostate gland, etc.
N x	No data. It is not known if there are metastases in the lymph nodes.
N 0	There are no metastases in the lymph nodes.
N 1	Metastases in the lymph nodes located around the rectum.
N 2	Metastases in the lymph nodes located in the inguinal and iliac region on one side.
N 3	Metastases in the lymph nodes around the rectum and in the groin. Metastases in the lymph nodes of the inguinal region on both sides. Metastases in the lymph nodes of the iliac region on both sides.
Mx	It is not known if there are distant organ metastases. Not enough data.
M0	There are no distant metastases in the organs.
M1	There are distant metastases in organs.

Stages of rectal cancer in accordance with the classificationTNM:

Stage	TNM classification
Stage 0	T is N 0 M 0
Stage I	T 1 N 0 M 0
Stage II	T 2-3 N 0 M 0
Stage IIIA	T 1 N 1 M 0 T 2 N 1 M 0 T 3 N 1 M 0 T 4 N 0 M 0
Stage IIIB	T 4 N 1 M 0 T any N 2-3 M 0
Stage IV	T any N any M 1

The condition of a patient suffering from rectal cancer depends on the presence or absence of metastases.

If the tumor is located within the rectum, then the patient is only concerned about digestive disorders, pain in the intestine, impurities of pus, blood and mucus in the feces.

If the tumor grows into neighboring organs, then there are symptoms characteristic of their defeat. With germination in the uterus and vagina - pain in the lower abdomen, violation of menstruation. With germination in the bladder - pain in the lower abdomen, impaired urination. With the spread of metastases to the liver - jaundice, pain under the ribs.

With multiple metastases, the general state patient: there is weakness, fatigue, exhaustion, anemia, fever.

Treatment of rectal cancer

Surgical treatment of rectal cancer

Surgical treatment is the main treatment for malignant tumors of the rectum. Other methods are used as a complement to it.

Operations on the rectum are among the most traumatic. Today, new techniques have been developed that allow maintaining a normal act of defecation and avoiding common postoperative complications.

Factors influencing the choice of surgical technique:

the size and location of the tumor;
the nature of the cellular structure of a malignant neoplasm;
tumor classification according to the TNM system.

Types of surgical interventions for rectal cancer:

Type of operation	Description
Resection of the rectal sector and anal sphincter (compressor muscle)	The essence of the method: Remove part of the lower rectum and anal sphincter. After that, they are completely restored. Indications: A tumor located in the region of the anal canal and sphincter, occupying less than 1/3 of their circumference, not growing beyond the rectum.
Resection (removal of part) of the rectum	The essence of the method: The surgeon removes part of the rectum, and the remaining, located above, sutured to the anal canal. Indications: A malignant tumor located in the lower part of the rectum, but above the anal canal, at the stage T 1 N 0.
Typical abdominoanal resection.	The essence of the method: The rectum is removed, leaving the anal canal and anal sphincters. sigmoid colon(which is located above the straight line) is lowered down and sutured to the sphincter. Indications: the tumor occupies less than the semicircle of the intestinal wall; the tumor is located 5-6 cm above the level of the anus; the tumor is located within the rectum and does not grow into neighboring organs; tumor stage - T 1-2 N 0.
Abdominal anal resection with removal of the internal sphincter (muscle sphincter)	The essence of the method: The operation is very similar to the previous one. In this case, the surgeon removes the internal sphincter located in the anal canal along with the intestine. A new artificial sphincter is created from the muscle layer of the sigmoid colon lowered down. Indications: To carry out this type of surgical intervention, the following conditions must be met: the tumor is located in the lower part of the ampoule of the rectum; the tumor grows into the muscular layer of the intestine, but does not spread beyond it; tumor stage - T 1-2 N 0.
Abdominal perineal extirpation (removal) of the rectum with bringing down into the wound of the sigmoid or colon.	The essence of the method: The surgeon completely removes the rectum. In its place, the end of the sigmoid colon is lowered down. An artificial muscle cuff is created in the anus, which should play the role of a pulp. Indications: To carry out this type of surgical intervention, the following conditions must be met: a fairly large malignant neoplasm of the lower part of the rectal ampulla; the tumor occupies no more than half of the circumference of the rectum; the tumor does not grow into the surrounding tissues; no metastases in the lymph nodes; tumor stage - T 1-2N0.
Abdominal-perineal extirpation (removal) of the rectum with the formation of an intestinal reservoir	The essence of the method: The surgeon completely removes the rectum and anal canal. The sigmoid colon descends. Operation features: an artificial cuff is formed in the anus, which should perform the functions of a pulp; the bowel is folded in such a way as to form an S- or W-shaped reservoir: this will help the patient better hold the stool. Indications: This type of surgical intervention is carried out at the stage of the tumor T 1-2 N 0, with its large extent.
Typical abdomino-perineal extirpation (removal) of the rectum.	The essence of the method: Completely remove the rectum and anal canal with the sphincter. The free end of the sigmoid colon is brought to the skin on the anterior surface of the abdomen (colostomy). Indications: This surgical intervention is performed at the tumor stage T 3-4 N0-2. the tumor is located in the lower part of the ampoule of the rectum; the tumor grows into fatty tissue that fills the pelvic cavity; metastases to regional lymph nodes are present or absent.
Evisceration of the pelvis	The essence of the method: Removal of all affected organs from the pelvic cavity: rectum, uterus, ovaries and vagina, seminal vesicles, prostate, ureters, Bladder, urethra, lymph nodes and part of fatty tissue. Indications: This surgery is performed when the tumor has spread to the lymph nodes and has spread to neighboring organs. Stage - T 4 N 0-2
Double-barreled colostomy	The essence of the method: The rectum is not removed. A hole is made in the wall of the sigmoid or colon, brought to the skin of the anterior surface of the abdominal wall. Indications: as a palliative (relieving the patient's condition) method in the later stages, when surgical treatment of the disease is no longer possible; as a temporary measure if surgical treatment of the tumor has been delayed. The main purpose of applying a double-barreled colostomy is to ensure the passage of feces in the development of intestinal obstruction.

Radiation therapy for rectal cancer

Indications for radiotherapy for malignant tumors of the rectum:

Preoperative period. Sessions are carried out daily for 5 days. The area where the tumor is located is irradiated directly. Surgical treatment is performed 3-5 days after the end of the course.

Postoperative period. The course of radiation therapy is started 20-30 days after the operation, if metastases in the regional lymph nodes have been confirmed. The tumor area and all lymph nodes of the pelvic region are irradiated. Sessions are held daily 5 days a week.

Late complications of radiotherapy for rectal cancer:

atrophy(reduction in size and dysfunction) internal organs: bladder, uterus, ureters, vagina, prostate, etc.
necrosis(death) of bones.

In order to prevent late complications of radiation therapy, the applied radiation is strictly dosed. After the course, rehabilitation is carried out. When symptoms of a complication appear, special treatment is prescribed.

Chemotherapy for colorectal cancer

Chemotherapy is prescribed as an adjunct to surgery for rectal cancer, in the postoperative period.

A drug	Description	How it is applied	Complications and methods of dealing with them
5-fluorouracil	This substance accumulates in the tumor tissue, blocks the synthesis of DNA and RNA, and inhibits the reproduction of cancer cells.	Solution for intravenous administration. 500 - 600 mg / m 2 of the body surface is prescribed daily for 5 days or every other day. The total dosage for the course is 4-5 days.	The most pronounced negative effect of fluorouracil on the state of the red bone marrow and the digestive system. Symptoms: a decrease in the content of leukocytes (white blood cells) and platelets (platelets) in the blood, suppression of immunity and blood clotting; loss of appetite, vomiting, diarrhea; ulcerative stomatitis; less often - dermatitis (skin lesions), hair loss. With a decrease in the level of leukocytes less than 5 * 10 3 / μl and platelets less than 100 * 10 3 / μl, the drug is canceled.
Ftorafur	Active substance- Tegafur. It accumulates in tumor cells and inhibits the enzymes responsible for the synthesis of DNA and RNA, inhibiting their reproduction.	Administer the drug by mouth or intravenous administration daily at a dosage of 0.8 - 1.0 g / m 2 of body surface per day. The total dose per course is 30 g.	As with fluorouracil
Polychemotherapy is a combination of different drugs.	5-fluorouracil - a substance that suppresses the synthesis of DNA and RNA, the reproduction of cancer cells; adriamycin - an antibiotic active against tumor cells; mitomycin-C is a drug that penetrates tumor cells and inhibits the formation of DNA and RNA in the later stages.	5-fluorouracil - 600 mg / m 2 on the 1st, 8th, 29th and 36th days, orally or intravenously; Adriamycin - 30 mg / m 2 on the 1st and 29th day, orally or intravenously; mitomycin-C 10 mg/m 2 intravenously via drip on the first day. Treatment with this combination begins on the 56th day after surgery.	Adriamycin: inhibition of the activity of the red bone marrow, decreased immunity, anemia, decreased blood clotting; toxic effect on the heart. Mitomycin-C: inhibition of the functions of the red bone marrow, like adriamycin. When expressed side effects, a significant drop in the level of leukocytes and platelets in the blood, drugs are canceled.

How to care for treated patients?

Patients who need special care:

who have recently undergone surgery for rectal cancer;
emaciated, in serious condition;
having a colostomy: the end of the intestine, brought to the skin of the anterior surface of the abdomen.

General principles for the care of bedridden patients:

frequent change of underwear and bed linen;
it is necessary to ensure that crumbs and dirt do not accumulate on the sheet;
prevention of bedsores: the patient must be periodically turned over, his position in bed should be changed, anti-decubitus mattresses can be used;
treatment of bedsores with camphor alcohol;
feeding the patient (if the patient cannot eat on his own, then a special probe is used);
hygiene procedures: daily washing, brushing teeth, periodic washing of the body with a damp sponge;
delivery of the vessel;
for incontinence of feces and urine, special diapers and pads are used.

Colostomy Care

Colostomy patients wear a special colostomy bag. The main care is associated with its periodic replacement. This can be done by the patient or caregiver.

Replacement of the colostomy bag:

carefully remove the used colostomy bag (most often they use adhesive ones - with a special sticker) from top to bottom, throw it away;
wipe the skin around the colostomy dry with a paper or gauze cloth;
wash the colostomy and the skin around it with warm boiled water;
dry the skin thoroughly with napkins;
lubricate the cream with an ointment or paste prescribed by a doctor;
remove the remnants of the cream from the skin with a napkin;
glue a new pouch onto the skin, following the manufacturer's instructions attached to it.

Diet for rectal cancer

Rules of nutrition for rectal cancer:

good nutrition, the inclusion in the diet of a sufficient amount of proteins, fats, carbohydrates, vitamins and minerals;
restriction of fatty meat food;
enrichment of the diet with vegetables and fruits;
full breakfast;
five meals a day in small portions;
thorough chewing of food;
exclusion from the diet of spicy, acidic, extractive foods.

Prognosis for rectal cancer

Factors affecting the prognosis for malignant neoplasms of the rectum:

stage of the disease;
cellular structure of the tumor;
the degree of differentiation of tumor cells (undifferentiated are the least favorable - see above);
the presence of metastases in the lymph nodes;
type of treatment provided.

If an operation was performed to remove the tumor without metastases, then 70% of operated patients survive within 5 years. In the presence of metastases in the lymph nodes of the rectum, inguinal and iliac region, this figure is reduced to 40%.

Dependence of the number of patients who survived for 5 years on the stage of the tumor process:

Stage I - 80%;
Stage II - 75%;
IIIA stage - 50%;
IIIB stage - 40%.

Prevention of rectal cancer

General preventive actions aimed at preventing rectal cancer:

Proper nutrition. Restriction in the diet of meat and fatty foods.

Sufficient physical activity, the fight against overweight.

Timely treatment of diseases of the rectum: anal fissures, hemorrhoids, polyps, etc.

Refusal of bad habits: alcohol, smoking.

Individuals with an unfavorable heredity and over the age of 50 are recommended to undergo an annual screening examination for colorectal cancer. It includes:

analysis of feces for occult blood;

sigmoidoscopy;

ultrasound procedure.

The rectum performs the function of defecation, the final function of the bowel. It is located in the back of the small pelvis and ends in the perineum.

In men, the prostate gland, the posterior surface of the bladder, the seminal vesicles, and the ampullae of the vas deferens are located in front of the rectum. In women, in front of the rectum are the uterus and the posterior fornix of the vagina. Behind the rectum lies next to the coccyx and sacrum.

The upper border of the intestine is located at the level of the upper edge of the third sacral vertebra.

The rectum is the final section. When it is not filled, longitudinal folds form in the mucous membrane. They disappear when the intestine is stretched.

The length of the rectum does not exceed 15 cm. Its upper part is surrounded by three transverse folds. The rectum ends with the anorectal region.

The rectum forms two bends. The sacral bend is curved towards the spine, and the perineal bend towards the abdominal wall. There are two sections of the rectum - pelvic and perineal. The boundary between them is the place of attachment of the muscle that lifts the anus. The pelvic region, located in the cavity of the small pelvis, consists of the supraampullary and ampullar regions. The ampulla is in the form of an ampulla with an extension at the level of the sacrum. The perineal part of the rectum is also called the anal (anal) canal. It opens outward through the anus.

Muscular membrane

The muscular layer of the rectum is formed by the outer longitudinal and inner circular layers. Transverse folds are formed by circular muscles. In the longitudinal layer are the fibers of the muscles that lift the anus. In the anal canal, 8-10 longitudinal folds are formed, the basis of which is smooth muscle and connective tissue.

The outlet section of the rectum is annularly covered by the muscular external sphincter of the anus (arbitrary sphincter). At a distance of 3-4 cm from the anus, a thickening of the circular muscles forms another sphincter (involuntary). At a distance of 10 cm from the anus, the circular muscles form another involuntary sphincter.

Blood supply to the rectum

The rectum is supplied by the superior and inferior rectal arteries. The superior rectal artery is a continuation of the inferior mesenteric artery, and the inferior rectal arteries are branches of the internal caval artery.

Due to this blood supply, the rectum is not involved in the pathological process during the development of ischemic colitis.

The outflow of blood occurs through the corresponding veins. These veins form plexuses in the wall of the rectum. In the submucosa of the anal canal, at the level of the anal valves, there is a cavernous vascular tissue. Recent studies have convincingly proven that it is she who forms hemorrhoids.

In the mucous membrane there are single lymphoid nodules and sebaceous glands. At the border of the intestinal mucosa and skin there are sweat glands and hair follicles. The mucous membrane of the rectum has a good suction capacity. This quality is used for the introduction of nutrient fluids and medicinal substances through the rectum by means of suppositories, enemas and irrigations.

innervation

From the point of view of the functions performed, the most important part of the smooth muscles of the rectum and anal canal is the internal sphincter. It provides residual pressure in the lumen of the rectum. The motor activity of this sphincter is inhibited and excited by both the sympathetic and parasympathetic nervous systems.

Functions of the rectum

The rectum performs two functions:

anal retention (stool accumulation)
defecation (evacuation of feces).

anal holding

Violation of the function of holding the intestinal contents of the rectum brings the greatest inconvenience to a person and creates problems of both a social and medical nature.

In its natural position, the internal anal sphincter is always contracted.
It relaxes only when the rectum is stretched. Immediately after the rectum is stretched and the internal sphincter is relaxed, the rectosphincteric relaxation reflex occurs.

The retention of intestinal contents is a normal condition and is regulated unconsciously. However, volitional influence on this function is also possible. Holding depends on the interaction of many factors.
Chief among them is the consistency of stool in the rectum and colon. No less important is the coordination of the activity of smooth and transverse circular muscles in the region of the anal canal. Of course, the anatomical integrity of all components of this process is necessary.

The smooth muscles of the anal canal, rectum, and internal anal sphincter respond to local stimuli and to reflexes transmitted by the autonomic nervous system.

The transverse muscles of the voluntary sphincter are controlled by the centers of the spinal cord and brain. This is carried out by centrifugal and centripetal nerve fibers.

So what has the biggest impact on holding function? It was assumed that this role is shared between the internal and external sphincters of the anus. However, the dissection of the internal sphincter only affects gas incontinence. And the dissection of the external sphincter also leads to gas incontinence and the difficulty of retaining a large amount of liquid stool.

It turned out that the holding function is determined mainly by the state of the puborectalis muscle, which maintains the required anorectal angle. When this muscle is damaged, severe fecal incontinence occurs.

defecation

Defecation is a complex process regulated reflexively. It is divided into two interrelated phases:

afferent and
efferent.

In the afferent phase, a urge is formed, and in the efferent phase, fecal masses are ejected.

The urge to defecate occurs when feces enter the rectum from the sigmoid colon. At the same time, they exert pressure on the puborectalis muscle, in which numerous receptors are located. Afferent excitations are transmitted to the cerebral cortex. Here there is an influence on the formation of the urge to defecate, it can be both inhibitory and enhancing the process.

When an urge occurs, stool masses continue to be retained in the rectum due to the internal and external sphincters. Emptying occurs reflexively and is controlled by an impulse from the central nervous system. If, when the urge occurs, the situation is unfavorable for defecation, then a voluntary contraction of the external sphincter causes the pelvic floor to rise, the anorectal angle increases and the feces are forced to rise up.

Regular inhibition of the defecation process when an urge occurs (volitional restraint) can lead to a violation of the regulatory functions of the body, which in turn will lead to constipation.

The influence of the central nervous system on this process has not been fully studied. So uncontrollable fecal incontinence can occur as an idiopathic phenomenon, but can occur with multiple sclerosis and other diseases of the nervous system.

In the elderly, constipation may occur due to weakening of the pelvic floor muscles and the diaphragm.

Strong emotional stress can cause involuntary relaxation of the internal and external sphincters and lead to a violation of the act of defecation, known as "bear disease".

Increased urges can also be caused by the effect of toxic substances on intestinal receptors. With various poisonings, this contributes to the accelerated removal of harmful substances from the body.

Table of contents of the topic "Anatomy of the large intestine":

Rectum. Topography of the rectum. Walls, relation to the peritoneum of the rectum.

Rectum, rectum, serves to accumulate feces. Starting at the level of the cape, it descends into the small pelvis in front of the sacrum, forming two bends in the anteroposterior direction: one, the upper one, facing backwards with a convexity, corresponding to the concavity of the sacrum - flexura sacralis; the second, lower, facing in the region of the coccyx with a bulge forward, - perineal - flexura perinealis.

upper rectum, corresponding flexura sacralis, is placed in the pelvic cavity and is called pars pelvina; towards flexura perinealis it expands to form ampulla - ampulla recti, with a diameter of 8 - 16 cm, but can increase with overflow or atony up to 30 - 40 cm.

The final part of the recti, heading back and down, continues in anal canal, canalis analis, which, having passed through the pelvic floor, ends with the anus, anus (ring - Greek proktos; hence the name of inflammation - proctitis).
The circumference of this section is more stable, it is 5 - 9 cm. The length of the intestine is 13 - 16 cm, of which 10-13 cm falls on the pelvic section, and 2.5 - 3 cm - on the anal. In relation to the peritoneum in the rectum, three parts are distinguished: the upper one, where it is covered by the peritoneum intraperitoneally, with a short mesentery - mesorectum, middle, located mesoperitoneally, and lower - extraperitoneal.

With the development of rectal surgery, it is now more convenient to use its division into five sections: supraampullary (or rectosigmoid), upper ampullar, middle ampullar, lower ampullar and perineal (or canalis analis).

The wall of the rectum consists of mucous and muscular membranes and located between them muscular plate of the mucous membrane, lamina muscularis mucosae, and submucosa, tela submucosa.

mucous membrane, tunica mucosa, due to the developed layer of the submucosa, it is collected in numerous longitudinal folds, which are easily smoothed out when the intestinal walls are stretched. AT canalis analis longitudinal folds in the amount of 8 - 10 remain constant in the form of the so-called columnae anales. The recesses between them are called anal sinuses, sinus anales, which are especially pronounced in children. Mucus accumulating in the anal sinuses facilitates the passage of feces through the narrow canalis analis.

The anal sinuses, or anal crypts as clinicians call them, are the most common portal of entry for pathogens.

In the thickness of the tissues between the sinuses and the anus is the venous plexus; its painful, profusely bleeding enlargement is called a hemorrhoid.

In addition to longitudinal folds, in the upper parts of the rectum there are transverse folds of the mucous membrane, plicae transversdles recti, similar to the semilunar folds of the sigmoid colon. However, they differ from the latter in a small number (3 - 7) and a helical course, which contributes to the forward movement of feces. submucosa, tela submucosa, strongly developed, which predisposes to the prolapse of the mucous membrane out through the anus.

Muscular membrane, tunica muscularis, consists of two layers: internal - circular and external - longitudinal. The inner one thickens in the upper part of the perineal region up to 5–6 mm and forms an internal sphincter here, i.e. sphincter ani internus, 2–3 cm high, ending at the junction of the anal canal with the skin. (Directly under the skin lies a ring of striated voluntary muscle fibers - m. sphincter ani externus, which is part of the muscles of the perineum).
The longitudinal muscle layer is not grouped into the teniae, as in the colon, but is distributed evenly on the anterior and posterior walls of the intestine. Below, the longitudinal fibers are intertwined with the fibers of the muscle that lifts the anus, m. levator ani (perineal muscle), and partly with the external sphincter.

From the above description it can be seen that the final segment of the intestine - the rectum - acquires the features of the conductor section of the digestive tube, like its initial part - the esophagus. In both these segments of the alimentary canal, the mucous membrane has longitudinal folds, the muscles are located in two continuous layers (the inner one is circular, narrowing and the outer one is longitudinal, expanding), and towards the opening that opens outward, the myocytes are supplemented with striated arbitrary fibers.
There is also a similarity in development: at both ends of the primary intestine, in the process of embryogenesis, the blind ends of the tube break through - the pharyngeal membrane during the formation of the esophagus and the cloacal - during the formation of the rectum. Thus, the similarity of development and function (conduction of contents) of the esophagus and rectum determines the well-known similarity of their structure.

In these similarities with the esophagus, the final part of the rectum differs from the rest of it, which develops from the endoderm and contains smooth muscles.

Topography of the rectum

Behind the rectum are the sacrum and coccyx, and in front of men, it adjoins with its section, devoid of peritoneum, to the seminal vesicles and vas deferens, as well as to the area of the bladder lying between them that is not covered by it, and even lower - to the prostate gland.
In women, the rectum in front borders on the uterus and the posterior wall of the vagina throughout its entire length, separated from it by a layer connective tissue, septum rectovaginale. Between the own fascia of the rectum and the anterior surface of the sacrum and coccyx there are no strong fascial bridges, which facilitates the separation and removal of the intestine during operations along with its fascia, covering the blood and lymphatic vessels.

Instructional video on the anatomy of the rectum

Anatomy of the rectum on the preparation of a corpse from Associate Professor T.P. Khairullina understands

Intestinal dysfunction, ), various inflammatory processes (, ), which contribute to prolonged irritation of the mucous membrane, lead to the appearance of papilla crypts at the bases, which are sometimes significantly enlarged. Hypertrophied papillae are mistaken for, while they are just a simple elevation of the normal mucosa.

The blood supply to the rectum is carried out by the upper, middle and lower hemorrhoidal arteries. Of these, the first artery is unpaired, and the remaining two are paired, approaching the intestine from the sides. The veins of the rectum run along with the arteries. The outflow of venous blood is carried out in two directions - through the portal system and through the vena cava system. In the wall of the lower intestine there are dense venous plexuses - submucosal and associated subfascial and subcutaneous, located in the region of the sphincter and anal canal.

Before turning to the physiology of the rectum, let us dwell briefly on the mechanism of formation of feces. It is known that an average of 4 liters of food slurry (chyme) passes from the small intestines to the large intestines in a person per day. In the large intestine (in the right section - in the caecum and ascending colon), due to tonic contractions, peristaltic and antiperistaltic movements, thickening, mixing of intestinal contents and the formation of feces occur. Of 4 liters of chyme in the colon, only 140-200 g of formed feces remain, which usually consists of the remains of digested food (fiber fibers, muscle and tendon fibers, grains covered with fiber, etc.), waste products of the intestine (mucus, exfoliated mucosal cells, cholic acid, etc.), as well as from living and dead bacteria.

The left half of the colon performs an evacuation function, which is facilitated by the so-called large and small movements. Small movements - continuously occurring small contractions that mix the contents of the intestine, large - intense rapid contractions of entire departments, helping to move the intestinal contents. They happen 3-4 times a day.

Food is evacuated from the stomach in an average of 2-2.5 hours. After 6 hours, the liquid intestinal contents, having traveled 5-6 m small intestine, moves to the large intestine, through which it passes for 12-18 hours. As already mentioned, approximately 4 liters of semi-liquid chyme passes from the small intestine to the large intestine per day. Over 3.7 liters of fluid during this time is absorbed just in the large intestine. Together with the liquid, toxic substances enter the bloodstream - the decay products of food and intestinal fermentation.

Venous blood saturated with these products flows through the portal vein system to where they are retained, neutralized and ejected from. Thus, the large intestine also has an absorptive function.

Bowel emptying - the act of defecation - occurs as a result of a complex interaction of a number of physiological mechanisms. With peristaltic movements, feces gradually move into. Accumulation and retention of feces occurs mainly due to contractions of the circular muscle layer of the intestine.

When lowering the stool into the ampulla of the rectum, new mechanisms come into play - reflex tonic contractions of the striated muscles of the external sphincter of the anus. The act of defecation consists of the following stages: filling the ampoule with feces, evacuation peristalsis of the rectum and sigma with reflex relaxation of the sphincters, simultaneous activation of the auxiliary muscle group (abdominal pressure and others). The rectum after a bowel movement remains empty for a long time.

It should be noted that the actions of the auxiliary muscle group, different in intensity, are aimed at accelerating and intensifying the evacuation of feces, especially in cases of its hard consistency or any pathological conditions(constipation, atony,).

The anus and rectum have a rich receptive field, here, when irritated, impulses arise that are transmitted to the stomach and affect its work, on, as well as bile secretion.

The emptying of the intestine is due to the influence not only of unconditioned (stretching of the ampoule), but also with the action of conditioned stimuli that create the usual rhythm of defecation at certain times of the day. The act of defecation is influenced by the cerebral cortex, which is confirmed by the following fact: a sudden mental or physical irritation can completely remove the already familiar stool and delay bowel movements for a long time.

As you can see, the main physiological function of the rectum - the act of defecation - is a complex process in which many mechanisms are involved. Any violation of them leads to a breakdown of this function.

The rectum (rectum) is the final section of the intestine.

Anatomy
The rectum begins at the level of the II-III sacral vertebrae and descends in front of the sacrum, having an S-shape with an extension in the middle part (printing Fig. 1). The upper bend of the rectum - sacral (flexura sacralis) - corresponds to the concavity of the sacrum, the lower - perineal (flexura perinealis) - is turned back. According to the bends, transverse folds (plicae transversales recti) are formed on the inner surface of the intestine - more often two on the left, one on the right.

In the middle part, the rectum expands, forming an ampulla (ampulla recti). The final section of the rectum - the anal canal (canalis analis) - is directed back and down and ends with the anus (anus). The length of the intestine is 13-16 cm, of which 10-13 cm fall on the pelvic region, and 2.5-3 cm on the perineum. The circumference of the ampullar part of the intestine is 8-16 cm (with overflow or atony - 30-40 cm).

Clinicians distinguish 5 parts of the rectum: supraampullary (or recto-sigmoid), upper ampullar, middle ampullar, lower ampullar and perineal.

The walls of the rectum consist of 3 layers: mucous, submucosal and muscular. The upper section of the rectum is covered in front and laterally by a serous membrane, which in the uppermost part of the intestine surrounds it and behind, passing into a short mesentery (mesorectum). The mucous membrane has a large number of longitudinal folds that easily expand.

Vessels and nerves of the rectum.
Rice. 1. Blood and lymphatic vessels of the rectum (frontal cut of the male pelvis; the peritoneum is partially removed, the mucous membrane of the rectum in its lower section is removed).
Rice. 2. Blood vessels and nerves of the rectum (sagittal section of the male pelvis).
1 - nodi lymphatici mesenterici inf.; 2-a. et v. rectales sup.; 3 - colon sigraoldeum; 4 - plexus venosus rectalis; 5-a. et v. rectales raedil sin.; 6 - plica transversa; 7 - nodus lymphaticus iliacus int.; 8-ra. levator ani; 9 - tunica muscularis (stratum circulare); 10 - muscle bundles in the region of columnae anales; 11 - m. sphincter ani ext.; 12 - m. sphincter ani int.; 13 - anus; 14-a. et v. rectales inf.; 15 - zona haemorrhoidalis (venous plexus); 16-a. et v. rectales medii dext.; 17 - tunica mucosa recti; 18 - rectum; 19-a. iliaca int.; 20-v. iliaca int.; 21 - nodus lymphaticus sacralis; 22-a. sacralis med.; 23 - plexus rectalis sup.; 24 - plexus sacralis; 25 - plexus rectalis med.; 26 - columnae anales; 27 - prostate; 28 - vesica urinaria; 29 - plexus hypogastricus int.; 30 - mesorectum.

In the anal canal there are 8-10 permanent longitudinal folds - columns (columnae anales) with depressions between them - anal sinuses (sinus anales), which end in semilunar folds - flaps (valvulae anales). The slightly protruding zigzag line from the anal flaps is called the anorectal, dentate, or pectinate, and is the boundary between the glandular epithelium of the ampulla and the squamous epithelium of the anal canal of the rectum. The annular space between the anal sinuses and the anus is called the hemorrhoidal zone (zona hemorrhoidalis).

The submucosal layer consists of loose connective tissue, which contributes to easy displacement and stretching of the mucous membrane. The muscular wall has two layers: inner - circular and outer - longitudinal. The first thickens in the upper part of the perineal region up to 5-6 mm, forming an internal sphincter (m. sphincter ani int.). In the region of the perineal part of the intestine, the longitudinal muscle fibers are intertwined with the fibers of the muscle that lifts the anus (m. Levator ani), and partially with the external sphincter. The outer pulp (m. sphincter ani ext.), unlike the inner one, consists of arbitrary muscles covering the perineal region and closing the rectum. It has a height of about 2 cm and a thickness of up to 8 mm.

The pelvic diaphragm is formed by the muscles that lift the anus, and the coccygeal muscle (m. coccygeus), as well as the fascia covering them. The paired muscles that lift the anus consist mainly of the iliococcygeal (m. iliococcygeus), pubococcygeal (m. pubococcygeus) and pubic-rectal (m. puborectalis) muscles and form a kind of funnel, lowered into the small pelvis. Its edges are attached to the upper sections of the inner walls of the small pelvis, and at the bottom, in the center of the funnel, the rectum is inserted, as it were, connected with the fibers of the muscle that lifts the anus. The latter divides the cavity of the small pelvis into two sections: upper-internal (pelvic-rectal) and lower-outer (sciatic-rectal). The upper inner surface of the muscle that raises the anus is covered with the fascia of the pelvic diaphragm (fascia diaphragmatis pelvis sup.), which connects to the own fascia of the rectum.

The peritoneal cover extends only to the upper anterior part of the rectum, descending in front to the Douglas space and rising from the sides to the level of the III sacral vertebra, where both serous sheets are connected to the initial part of the mesentery.

Attached to the edges of this downwardly elongated oval of the peritoneal cover is the proper fascia of the rectum, denser behind and relatively less pronounced from the sides, and in front turning into a dense prostate-peritoneal aponeurosis (in men) or rectovaginal aponeurosis (in women). This aponeurosis is easily divided into two plates, of which one dresses the prostate gland with seminal vesicles, and the other - the anterior wall of the rectum; this facilitates the separation of these organs during surgery. Extrafascial removal of the rectum together with the efferent lymphatic vessels without disturbing their integrity is considered the most important condition for a radical operation.

blood supply rectum (printing table, Fig. 1 and 2) is carried out through an unpaired upper rectal (a. rectalis sup.) and through two paired - middle and lower - rectal arteries (aa. rectales med. et inf.). The superior rectal artery is the terminal and largest branch of the inferior mesenteric artery. A good vascular network of the sigmoid colon allows you to maintain its full blood supply, provided that the marginal vessel is left intact even after a high intersection of the upper rectal and one to three lower sigmoid arteries. The safety of crossing the artery above the "critical point of Zudek" can only be ensured while maintaining the integrity of the marginal vessel. The blood supply to the entire rectum to the anal part is carried out mainly due to the superior rectal artery, which is divided into two, and sometimes more branches at the level of the III-IV sacral vertebrae.

The middle rectal arteries, coming from the branches of the internal iliac artery, are not always equally developed and are often completely absent. However, in some cases they play an important role in the blood supply to the rectum.

The inferior rectal arteries, originating from the internal pudendal arteries, feed mainly on the external sphincter and the skin of the anal region. There are good anastomoses between the ramifications of the systems of the upper, middle and lower rectal arteries, and the intersection of the superior rectal artery at different levels while maintaining the integrity of the middle and lower rectal arteries and their numerous nameless branches in the anterior and lateral sections of the rectum, it does not deprive the lower segment of the intestine of nutrition.

Venous plexuses of the rectum (plexus venosi rectales) are located in different layers of the intestinal wall; There are submucosal, subfascial and subcutaneous plexuses. The submucosal, or internal, plexus is located in the form of a ring of dilated venous trunks and cavities in the submucosa. It is associated with the subfascial and subcutaneous plexuses. Venous blood flows into the portal vein system through the superior rectal vein (v. rectalis sup.) and into the inferior vena cava system through the middle and inferior rectal veins (vv. rectales med. et inf.). There are many anastomoses between these systems. The absence of valves in the superior rectal vein, as well as in the entire portal system, plays an important role in the development of venous congestion and dilatation of the veins of the distal segment of the rectum.

lymphatic system . The lymphatic vessels of the rectum are important because tumors and infection can spread through them.

In the mucous membrane of the rectum there is a single-layer network of lymphatic capillaries connected to a similar network of the submucosal layer, where a plexus of lymphatic vessels of I, II and III orders is also formed. In the muscular membrane of the rectum, a network of lymphatic capillaries is formed, made up of capillaries of the circular and longitudinal layers of the rectum. In the serous membrane of the rectum there are superficial (small-looped) and deep (wide-looped) networks of lymphatic capillaries and lymphatic vessels.

The efferent lymphatic vessels generally follow the course of the blood vessels. There are three groups of extramural lymphatic vessels: upper, middle and lower. The upper lymphatic vessels, collecting lymph from the walls of the rectum, are directed along the branches of the superior rectal artery and flow into the so-called Gerota's lymph nodes. The middle rectal lymphatic vessels run from the lateral walls of the intestine under the fascia covering the levator ani muscle towards lymph nodes located on the walls of the pelvis. The lower rectal lymphatic vessels originate in the skin of the anus and are associated with the lymphatic vessels of the anal mucosa and ampulla. They go in the thickness of the subcutaneous fatty tissue to the inguinal lymph nodes.

Lymph outflow, and consequently, the transfer of tumor cells can go in many directions (see below).

The innervation of the recto-sigmoid and ampullar parts of the rectum is carried out mainly by the sympathetic and parasympathetic systems, the perineal - mainly by the branches of the spinal nerves (tsvetn. Fig. 2). This explains the relatively low sensitivity of the rectal ampulla to pain and the high pain sensitivity of the anal canal. The internal sphincter is innervated by sympathetic fibers, while the external sphincter is innervated by branches of the pudendal nerves (nn. pudendi) that accompany the lower rectal arteries. The levator ani muscle is innervated by branches coming mainly from the III and IV sacral nerves, and sometimes from the rectum. This is important in resection of the lower sacral vertebrae for access to the rectum, as it indicates the need to cross the sacrum below the third sacral foramen in order to avoid serious dysfunction not only of the levator ani and the external sphincter, but also of other pelvic organs.