The human gastrointestinal tract, part of which is represented by the large intestine, is distinguished by a variety of departments and features of their functioning. At the same time, it is the digestive system, due to regular contact with various irritants, that is most susceptible to development. various pathologies. However, it is quite difficult to establish what exactly caused the malaise. To identify dysfunction in each section of the intestine, a certain research methodology is used. This significantly reduces the effectiveness of diagnosing digestive disorders. Often, patients also do not pay attention to discomfort v abdominal cavity leading to late detection of bowel disease. To avoid the development of complications, you should seek medical help when the first symptoms of the pathology appear.
The large intestine is a large hollow organ digestive tract. He performs many important functions while constantly in contact with the food masses. As a result, the colon is constantly exposed to various harmful factors that can cause a deterioration in its functioning. Diseases of this department of the digestive system, according to medical statistics, are the most common today.
The large intestine is the last section gastrointestinal tract. The length of this section is from 1.1 to 2-2.7 meters, and the diameter reaches 5-6 cm. It is much wider small intestine, about 2.5 times. The lumen of the large intestine narrows closer to the exit from the rectum, which ends with a sphincter, allowing for normal voluntary defecation.
Features of the structure of the walls of the large intestine
The walls of the large intestine are made up of four layers:
- mucous;
- submucosal;
- muscular;
- seroses.
All these sections of the intestinal wall ensure the normal functioning of the organ and its peristalsis. Normally, the large intestine produces a sufficiently large amount of mucus that promotes the movement of chyme through the digestive tract.
Attention! Chyme is a lump formed by food masses, desquamated epithelial cells, acids and enzymes. Chyme is formed in the stomach, changing its consistency as it moves through the gastrointestinal tract.
Bowel functions
The large intestine ensures the completion of the movement of chyme through the digestive tract. She communicates with external environment, which determines the specifics of its functions:
- excretory. The main function of the large intestine. It is aimed at removing various pathogens and unprocessed substances from the body. This process must occur regularly and not have failures, otherwise, due to the abundance of toxins in the digestive tract, poisoning of the body develops. It is in the large intestine that the stool is finally formed, which is then excreted from the rectum. Excretory function stimulates next move food. After a person eats food, his brain receives a signal that increases intestinal motility and accelerates the movement of chyme towards the anus.
- digestive. Most of nutrients are absorbed in the small intestine, however, some of the components of the chyme enter the body from the large intestine: salts, amino acids, fatty acid, monosaccharides, etc.
- Protective. The large intestine contains about three kilograms of beneficial microflora, which not only ensures normal digestion, but also contributes to the functioning of the immune system. Bacterial imbalance leads to a decrease in protective function organism, increased susceptibility infectious diseases etc.
- Suction. It is in this section of the digestive system that the main part of the liquid is removed from the feces - more than 50%, which prevents dehydration of the body. Due to this, feces acquire a characteristic texture and shape.
The large intestine has general functions, while each of its departments also performs its own tasks, due to the peculiarities of physiology.
Sections of the large intestine
The large intestine has a rather complex structure and consists of several sections:
- the caecum, which has an appendage - the appendix;
- colon: ascending colon, transverse colon, descending colon, sigmoid colon;
- rectum.
Attention! The lumen of all sections of the large intestine contains a large number of various microorganisms. They form the normal intestinal microflora. Bacteria break down various components of chyme and provide the production of vitamins and enzymes. The optimal functioning of all parts of the intestine is the key to proper digestion.
Cecum
The large intestine begins with a blind section, which is localized in the right iliac region. Its shape resembles a bag delimited by two sphincters: the ileocecal valve separates the small intestine, and the Gerlach valve prevents digestion from entering the appendix.
Attention! The appendix is an appendage of the caecum. Its diameter does not exceed 0.6 cm, and the length varies from 2.7 to 12-13 cm.
It is the caecum that is the site of development most various diseases of the large intestine. This is due to both morphological and physiological features of this department. Pain in diseases of the caecum is localized in the right paraumbilical region or above the ilium.
Colon
The main part of the large intestine is represented by the colon. Its length reaches 1.7 meters, and its diameter is about 5-7 cm. The colon is separated from the blind fragment of the intestine by the Busi valve.
The colon is divided into four sections:
- ascending colon;
- transverse;
- descending;
- sigma.
The ascending section is not involved in the main process of digestion of food, however, it provides absorption of fluid from the chyme. It is in this fragment of the digestive tract that up to 30-50% of water is removed from the feces. ascending colon is a continuation of the blind, while its length varies from 11 to 20 cm. This area is located at the posterior wall of the abdominal cavity on the right. If any pathology affects the ascending intestine, then the pain syndrome is localized in the area from the ilium to the hypochondrium.
The ascending section passes into the transverse, starting in the hypochondrium on the right. The length of this fragment can be from 40 to 50 cm. In the transverse intestine, fluid is also absorbed from the chyme, as well as the production of the enzyme necessary for the formation of fecal masses. In addition, it is in this section that pathogenic microorganisms are inactivated. With the defeat of the transverse section, discomfort occurs in the area 2-4 cm above the navel.
The descending colon has a length of about 20 cm and is located downward from the left hypochondrium. This section of the intestine is involved in the breakdown of fiber and contributes to the further formation of feces. In the left iliac fossa, the descending section passes into the sigmoid. Sigma has a length of up to 55 cm. Due to the peculiarities of the topography, pain in the course of various pathologies of this organ can be localized both in the abdomen on the left, and radiate to the lower back or sacral region.
Rectum
The rectum is the terminal, that is, the final, section of both the large intestine and the entire digestive tract. This part of the digestive tract is distinguished by the specific structure and functioning.
The rectum is located in the pelvic cavity. Its length does not exceed 15-16 cm, and the distal end ends with a sphincter that communicates with the external environment.
Attention! In this section of the intestine, the final formation and accumulation of feces occurs immediately before defecation. Due to the peculiarities of physiology, it is the rectum that is most susceptible to various mechanical damage: scratches, cracks, irritation.
Pain in violation of the rectum is localized in the perineum and anus, can radiate to the pubic area and genitals.
Video - Three tests for bowel disease
Pain syndrome in the lesion of the large intestine
Many different diseases can provoke pain in the large intestine. A number of factors lead to the development of such violations:
- sedentary lifestyle;
- violation eating behavior, including frequent overeating or following a strict diet;
- abuse of spicy, fatty, smoked foods;
- disruption of the digestive system in patients due to advanced or senile age;
- chronic constipation;
- hypotension, accompanied by impaired peristalsis;
- constant use of pharmacological drugs.
These factors can cause disturbances in the work of both the entire digestive tract and the large intestine separately. At the same time, to establish the cause of the appearance pain syndrome usually quite difficult, and almost impossible on your own. In general, dysfunctions of the digestive system can be divided into two main groups:
- inflammatory nature: colitis, diverticulitis, Crohn's disease, etc.;
- non-inflammatory disorders: atonic constipation, tumor processes, endometriosis, etc.
Colon diseases can significantly impair a patient's quality of life. In order to prevent the development of complications, it is necessary to pay attention in a timely manner to the appearance warning signs pathology.
Ulcerative colitis is an inflammatory disease of the large intestine. The disease has a chronic course and is characterized by fairly frequent relapses. To date, it has not been possible to accurately determine the cause of the development of pathology, but it is classified as a disorder of autoimmune origin.
Attention! Colitis occurs most frequently in people of two age groups: patients 25-45 years old and patients over 55-60 years old.
- acute colitis;
- chronic with periodic exacerbations;
- chronic continuous, in which remission is not observed for 6 months or more.
Clinical picture ulcerative colitis in general, it is synonymous with other diseases of the large intestine and is manifested by the following symptoms:
- Intense, long-lasting pain in the abdomen. Their localization largely depends on which part of the colon was affected by the pathological process.
- Diarrhea or constipation. In this case, bloody inclusions may be noted in the feces.
- Signs of intoxication of the body: nausea, cephalgia, dizziness, drowsiness and lethargy.
Attention! Lack of therapy for colitis can lead to perforation of the intestinal wall and, as a result, massive intestinal bleeding. This condition is life-threatening for the patient.
Colitis therapy should be carried out in a complex manner, taking into account the severity and form of the disease. With a radical lesion of the intestine, the patient is hospitalized.
Therapy for ulcerative colitis
| Name of the drug | Image | pharmachologic effect |
|---|---|---|
 | Anti-inflammatory and antimicrobial agent | |
 | Anti-inflammatory and cytoprotective action | |
 | Anti-inflammatory, immunosuppressive effect | |
 | Immunosuppressive agent |
Crohn's disease
Crohn's disease is also an inflammatory disease. Pathology is manifested by the development of granulomatosis.
Attention! Granulomatosis - the formation of granulomas, that is, nodular neoplasms. Such growths can occur on the skin, mucous membranes, vascular walls, etc.
Unlike nonspecific colitis, Crohn's disease can affect not only the walls of the large intestine, but also the tissues of the small intestine, stomach and esophagus. Depending on the severity of the pathological process, the number of foci of inflammation varies from one to several dozen.
Modern medicine has not yet established the cause of this disease. It has been determined that drugs with antibiotic action have positive effect, therefore, a bacterial origin of the pathology is assumed.
Allocate acute and recurrent forms of the disease. chronic course observed only in patients with impaired immune system or severe dysfunction of the digestive tract.
The disease is manifested by a variety of symptoms:
- intense sharp or cutting pain, localized in the area of inflammation;
- the appearance of rashes on the skin;
- rapid weight loss of the patient;
- bloating;
- violation of the chair;
- pain during bowel movements, the appearance of fistulas around the anus.
Patients with Crohn's disease are advised to follow a diet with high content proteins and the exclusion of milk and dairy products. In addition, a mandatory part of therapy is drug treatment.
Therapy for Crohn's disease
| Name of the drug | Image | pharmachologic effect |
|---|---|---|
 | Anti-inflammatory, antibacterial effect | |
 | Decongestant, antihistamine action– corticosteroid | |
 | Immunosuppressive drug | |
 | Antidiarrheal agent | |
 | Pain relief effect |
diverticular disease
Diverticular disease is manifested by two characteristic conditions:
- diverticulosis - pathological process in which numerous small protrusions form on the walls of the large intestine, which are called diverticula;
- diverticulitis - inflammation of diverticula as a result of infection.
A similar pathology occurs as a result of excessive pressure on the intestinal wall of its contents. Due to the weakness of the intestinal tissues, sagging and protrusions are formed, which may not cause any inconvenience to the patient for a long period of time. Main clinical symptoms develops only in case of infection of the diverticulum.
Attention! The main cause of diverticular disease is constipation. Constipation leads to constant excessive stress on the colon. It was revealed that the vast majority of patients suffering from diverticulosis consume insufficient amounts of vegetable fiber and suffer from regular stool disorders.
Diverticulitis is manifested by the following symptoms:
- intense pain;
- nausea;
- persistent violations of defecation;
- bad breath;
- feces with undigested food.
It is worth noting the specificity of the pain syndrome in diverticulitis:
- pain syndrome is localized in the lower third of the abdomen on the left;
- pain can persist for 4-7 days or more;
- on palpation, the pain increases sharply.
Drug treatment of diverticulitis includes several groups of drugs for a complex effect on the pathological process.
Therapy for diverticular disease
| Name of the drug | Image | pharmachologic effect |
|---|---|---|
 | Antibacterial action | |
 | Prebiotic with laxative effect | |
 | Stimulation of gastrointestinal motility | |
 | Antispasmodic effect | |
 | Analgesic action |
With no effect from conservative therapy the patient needs surgery.
Malignant neoplasms
Neoplasms of the large intestine can be either malignant or benign character. At the same time, the first group of tumors is characterized by slow growth and does not cause a pronounced deterioration in the quality of life of the patient.
Carcinomas develop more aggressively, resulting in a characteristic clinical picture cancer disease:
- bouts of vomiting, admixture of feces in vomit;
- loss of appetite leading to cachexia;
- lethargy, drowsiness, weakness;
- subfebrile fever;
- stool disorders;
- melena - black feces with an admixture of blood;
- cutting and tearing pains in the area of tumor formation.
The thick gastrointestinal tract is an important part of the digestive system. Pain in this section of the gastrointestinal tract may indicate the development of serious pathologies and require urgent consultation with a specialist.
And its meaning. We will also get acquainted with its anatomical structure, analyze in detail the role of the layers of which it consists, and study the processes of blood supply.
General information about the rectum
The rectum is necessary for the body to accumulate feces. It originates in the region of the cape, then descends into the cavity of the small pelvis, located in front of the sacrum. Such a structure forms 2 bends moving from the front to the back and are called the upper and lower. The upper one is convex in the direction of the concavity of the sacrum, and the lower one looks into the coccyx area. Sometimes it is called perineal.
Upper section and end
Features of the structure and functions of the rectum depend primarily on its constituent elements, departments, cells and location. One of these components is the upper part of the organ and its final part.
The upper section is a kind of ampulla, the diameter of which is usually in the range of 8-16 cm, but this number may increase due to, for example, atony. This formation is located in the pelvic cavity and expands at one end.
The end part is represented by a circle directed downward and backward, and its continuation is in the anal canal. After passing, it ends with a hole. The dimensions of the formed circle vary less than that of the upper section, and correspond to 5-9 cm. The size of the intestine ranges from 13 to 16 cm, but about 65-85% of it falls on the pelvis, and the remaining centimeters form the anal section.
The structure of the mucous membrane
The functions of the human rectum are largely determined by its mucous membrane. The mucous membrane forms a numerous number of longitudinal folds, which is possible due to its developed submucosa. These folds can easily be smoothed out due to stretching of the intestinal wall. The anal canal has folds with permanent view; there are eight to ten of them. These formations have special depressions that lie between them, and are called anal sinuses (clinicians), which are clearly expressed in children. It is clinicians who accumulate in themselves a special mucus that facilitates the passage of feces through the anal canal. The anal sinuses are also called anal crypts. They most often serve as an entrance door for microorganisms. The tissue thickness, located between the anus and sinuses, includes a plexus of veins. In addition to longitudinal folds, upper divisions rectum have transverse folds. These formations are very similar to the semilunar folds of the sigmoid colon.
Description of the muscularis
The structure and functions of the rectum also depend and are determined by the muscular membrane, which consists of 2 layers, namely: circular and longitudinal. The circular (inner) layer begins to thicken in the upper part of the perineum. It is in this area that the internal sphincter is formed, which ends at the junction of the skin and the anal canal. The longitudinal layer covers both the anterior and posterior sections of the intestine, equally. In the lower part, the longitudinal fiber begins to intertwine with the muscular one, rising towards the anus, and also often intertwines with the external sphincter.
Thanks to this, we can conclude that the rectum has the features of a conductive department. alimentary canal and similar to the esophagus. There is a similarity between these structures in the process of development: both ends of the primary gut during embryogenesis undergo a breakthrough of the blind end of the tube. In the esophagus, this occurs with the pharyngeal membrane, and in the rectum, with the cloaca. Both canals have musculature consisting of two continuous layers.
topographic information
The functions of the rectum can be described with topographic information. Behind the organ are two sections of the spine, sacral and coccygeal. And in front of the males, the intestine is adjacent to the seminal vesicles and the rectum of women borders in the anterior area on the posterior vaginal wall and uterus. It is separated from these structures by a layer formed by connective tissue.
The proper fascia of the rectum and the anterior surface of the sacral and coccygeal spine do not have fascial bridges between them. This simplifies operations to remove the intestine and its fascia, which has covered the vessels. Doctors do not have any particular problems with this.
Functions of the rectum. Description
One of the functions of the rectum is to retain food residues that have not had time to be absorbed in the cavity small intestine, as well as water. There are a lot of substances in here. organic nature and products that have undergone bacterial decay, and also contain substances that cannot be digested, for example, fiber. There is also bile, bacterial organisms, salts.
In connection with the functions of the rectum, processes such as the breakdown of food that have not been digested in other parts of the food section are observed there. And the formation of feces. In the large intestine, digestive juice is constantly secreted, containing the same set of enzymes as in the small intestine, but with a less pronounced effect. This is where the collection of gases takes place.
The key function of the rectum is the removal of waste products from the life process. Or, in other words, the removal of feces from the body. Mostly this process is regulated by the consciousness and will of a person.
Violation of the function of the rectum, as a rule, is the result of a sedentary lifestyle, poor nutrition, neuro-emotional overload, etc. Most often, such stressful situations lead to constipation. To disruption of the intestines, affecting the process of defecation.
Circulatory processes
The blood supply to the rectum is due to the unpaired upper rectum and two paired rectal. A well-developed network of vessels of the sigmoid colon makes it possible to preserve the unpaired rectal artery, namely its marginal vessels, full blood supply even due to high intersections of the rectal paired arteries and the sigmoid.
The middle paired arteries emerging from the branch sometimes develop differently, and sometimes they are absent. And, nevertheless, in some situations they can play a key role in the process of blood supply.
The inferior arteries, originating from the internal pudendal artery, supply the external sphincter and skin. Plexuses from the veins are located in a wide variety of layers of the intestinal walls. Among them are:
- submucosal plexus - has an annular shape, consists of a submucosa and venous trunks, and is also associated with the other two plexuses;
- subfascial plexus;
- subcutaneous plexus.
Finally
If we talk briefly about the function of the human rectum, we can sum it up as follows. This body is responsible, first of all, for the place of storage of feces and the reservoir for the accumulation of gas. Also here is the breakdown of undigested food and the removal of waste products of the life process.
Rectum, located in the cavity of the small pelvis, at its back wall, formed by the sacrum, coccyx and posterior pelvic floor muscles. It starts from the end of the pelvic part of the sigmoid colon at the level of the III sacral vertebra and ends in the perineum with the anus. Its length is 14-18 cm. The diameter of the rectum varies from 4 cm (beginning from the sigmoid colon) to 7.5 cm in the middle part (ampulla) and again decreases to a gap at the level anus.
Consists of two parts: pelvic and perineal. The first is located above the pelvic diaphragm, in the cavity of the small pelvis, and, in turn, is subdivided into a narrower supraampullary section and a wide ampulla of the rectum, ampulla recti. The second part of the rectum lies under the pelvic diaphragm, in the perineum, and represents the anal (anal) canal, canalis analis.
The pelvic part of the rectum forms a bend in the sagittal plane, open anteriorly, respectively, to the concavity of the sacrum, the sacral bend, flexura sacralis; the upper part of the bend of the intestine follows from front to back and down, the lower part from back to front and down.
In the frontal plane, the pelvic part forms non-permanent bends; the upper part of the bend goes from top to bottom to the left and to the right, the lower part goes in the opposite direction. The second bend in the sagittal plane, but already concave back, is located at the transition of the pelvic part to the perineum; having passed the diaphragm of the pelvis, the rectum sharply turns (almost at a right angle) back, forming a perineal bend, flexura perinealis. At this level, the rectum, as it were, goes around the top of the coccyx. The length of the pelvic part ranges from 10 to 14 cm, the perineal part is about 4 cm.
At the level of the lower edge of the third sacral vertebra, the rectum begins to lose its serous cover: first from the posterior surface, then from the lateral, and finally from the anterior. Thus, the upper, nadampular, section of the pelvic part of the rectum is located intraperitoneally, the upper part of the ampulla is surrounded by a serous membrane on three sides, and the lowest section of the ampulla lies retroperitoneally, since the peritoneum covers only a small area of the anterior wall here.
The line along which the peritoneum leaves the intestinal wall follows obliquely from above, from back to bottom and forward. As the wall of the pelvic region of the rectum loses its peritoneal cover, it is replaced by the visceral fascia of the pelvis, which forms the rectal sheath.
The perineal part of the rectum has the form of a longitudinal slit and opens in the deepening of the intergluteal groove with the anus, anus, almost midway between the coccyx and the root of the scrotum in men or the posterior commissure of the labia majora in women, at the level of the transverse line connecting both ischial tuberosities.
The structure of the wall of the rectum.
The serous membrane (peritoneum), tunica serosa, is part of the wall of the rectum only to a small extent. The extraperitoneal part of the pelvic region of the rectum is surrounded by the visceral fascia of the pelvis; the fascia is not directly adjacent to the muscular layer of the intestinal wall. Between the visceral fascia and the muscle layer lies a layer of fatty tissue, there are nerves that feed the intestines, blood vessels and The lymph nodes. Anterior section fascia of the rectum is a plate that separates the intestine from the organs lying in front: Bladder, prostate, etc. This plate is a derivative of fused serous sheets of the deepest part of the peritoneal pocket of the small pelvis; it goes from the bottom of the recto-uterine recess (or rectovesical recess in men) to the tendon center of the muscles of the perineum and is called the peritoneal-perineal fascia, fascia peritoneoperinealis, or rectovesical septum, septum rectovesicale. Dorsal rectal fascia ends at middle line posterior wall of the rectum.
The muscular membrane, tunica muscularis, of the rectum consists of two layers: the outer longitudinal, stratum longitudinale, less thick, and the inner circular, stratum circulare, thicker. The longitudinal layer is a continuation of the muscle bands of the sigmoid colon, which expand here and cover the intestine in a continuous layer. On the anterior and posterior walls, the longitudinal muscle bundles are more developed. The bundles coming from the anterior sacrococcygeal ligament are woven into the longitudinal muscle layer of the lower part of the ampoule - the rectococcygeal muscle, m. rectococcygeus. Part of the muscle fibers of the longitudinal layer is woven into the muscle that lifts the anus, m. levator ani, and part reaches the skin of the anus.
In men, on the anterior surface of the lower portion of the rectum, part of the longitudinal muscle bundles forms a small recto-urethral muscle, m. rectourethralis. This muscle is attached to the tendinous center of the perineum at the point where the membranous part of the urethra passes through it. In addition, slightly higher in men, there is a rectovesical muscle, which is a muscle bundle that connects the longitudinal muscle bundles of the bladder with the same bundles of the rectum.
The circular muscle layer of the rectum extends to the very anus; here it thickens, forming the internal sphincter of the anus, m. sphincter ani internus. Anterior to the anus, the bundles of its muscles are woven into the pulp of the membranous part of the urethra (in men) and into the muscles of the vagina (in women). Around the anus subcutaneous tissue located external sphincter of the anus, m. sphincter ani externus. This muscle belongs to the group of striated muscles of the perineum. Its outer, more superficial part covers medial section muscles that lift the anus; the deeper part is adjacent to the circular layer of the rectum, which forms the internal pulp here. The levator ani muscle enters the gap between the external and internal sphincters of the rectum. The anterior part of this muscle is the pubococcygeal muscle, m. pubococcygeus, covers the back of the perineal part of the rectum in the form of a loop.
The muscles of the circular layer of the rectum form thickenings at the location of the transverse folds of the mucous membrane (see below). The most pronounced thickening is 6-7 cm above the anus. Here, the transverse folds of the rectum, plicae transversales recti, are clearly distinguished; the middle of them is the most pronounced, in its thickness lies a large number of circular muscle fibers.
The mucous membrane, tunica mucosa, of the rectum is covered with epithelium, contains intestinal glands (crypts), glandulae intestinales (criptae), but is devoid of villi; in the submucosa, tela submucosa, there are single lymphatic follicles. Throughout the pelvic region of the rectum, the mucous membrane forms three, sometimes more, transverse folds, plicae transversales recti, covering half the circumference of the intestine. Of these three folds, the upper one is located at a level of up to 10 cm from the anus. In addition to transverse folds, the mucous membrane has a large number of irregular folds running in different directions. The mucous membrane of the lower part of the rectum (anal, anal, canal) forms up to 10 longitudinal folds - anal (anal) columns, columnae anales, the width and height of which increase downwards. The upper ends of the anal columns correspond to the rectal-anal line, linea anorectalis. Distal to the anal columns is a slightly swollen annular area with a smooth surface of the mucous membrane - the intermediate zone. The protruding intermediate zone, as it were, closes the recesses between the pillars from below, turning them into pockets - the anal (anal) sinuses, sinus anales. At the bottom of these sinuses are the anal glands. The transverse folds of the intermediate zone, closing the sinuses from below, as if connecting the anal columns, are called anal (anal) valves, valvulae anales. The totality of the anal flaps forms a cushion of the mucous membrane - the anal (anal) crest, pecten analis. The submucosa of the anal column zone and the intermediate zone is a loose fiber in which the rectal venous plexus lies. In the intermediate zone, this plexus forms a continuous ring; in the submucosa of the region of the anal columns, except venous plexuses, lie bundles of longitudinal muscle points.
Approximately the same for women and men. But since the intestines are located somewhere in the same area as the genitals, there are some peculiarities and differences.
This article discusses the structure of the organ in men and women, its functions and possible diseases.
More about the rectum
This organ descends to the small pelvis, forming bends. One of them bulges forward, and the other bulges back, repeating the curve of the sacrum.
The length of the intestine is from 10 to 15 cm. The organ consists of muscle tissue, mucous membrane and submucosa, is located in the connective tissue membrane - in the male body it also covers the prostate gland, and in the female body it envelops the cervix.
The mucous membrane is covered epithelial tissue, which contains a large number of Lieberkühn crypts (glands).
In turn, these glands are made up of cells that produce mucus, which explains why mucus is secreted from the intestines in various diseases.
Just above the anus are Morgagni's rectal columns, formed by a fold of mucous tissue. They resemble columns, their number varies from 6 to 14.
Between the columns are niches, which are called pockets. They often retain the remains of feces, which can provoke inflammation.
Intestinal diseases and disorders motor function irritate the intestinal mucosa, due to which papillae may appear on it, the size of which depends on how strongly the mucosa is irritated. Sometimes irritation is mistaken for a polyp.
Blood in the rectum comes from several hemorrhoidal arteries - from the lower, middle and upper. The first two are paired, but the top one is not.
Blood through the veins moves through the caval and portal, in the lower part of the rectum there are many large venous plexuses.
In women, the structure of the intestine is different from the male body. This is influenced by the characteristics of the female reproductive system.
In women, the rectum is adjacent to the vagina in front - between the organs, of course, there is a separating layer, but it is very thin.
If inflammation occurs in one of these organs, then it is likely that it will spread to a neighboring organ.
Because of this internal structure in women, fistulas often form, which affect both the intestine and the organs of the reproductive system.
This disease is a consequence of problematic childbirth or any injuries.
The rectum is the last part of the intestine that ends with the sphincter. Surprisingly, the anus in men and women has a different structure.
The sphincter or anus is a depression that goes into the rectum. Depending on the structure of the body, it may be located deep enough or not very deep.
In men, for example, the sphincter may be funnel-shaped, while in women it is flatter and protrudes slightly forward.
Such a structure of the sphincter may be in women from the fact that its muscles are stretched too much.
How does defecation happen?
The rectum is a part of the large intestine, which also includes the sigmoid, ascending, descending and transverse. It is necessary to understand how everything works as a whole in order to consider the rectum separately.
In men and women, about 4 liters of digested food (chyme) that comes from the stomach comes from the small intestine to the large intestine per day.
The large intestine mixes this gruel, as a result of which feces are formed in a person.
This happens due to the fact that the body performs wave-like contractions, due to which the chyme thickens. In the end, out of 4 liters of digested food, about 200 g of feces remain.
Usually stool consist not only of chyme residues, but also of mucus, cholesterol, bacteria, cholic acid, etc.
The body absorbs food, and all the toxic and harmful substances of the chyme penetrate into the blood, which enters the liver. In the liver, "harmful" blood lingers, and then is thrown out with bile.
After all this, a bowel movement occurs, which is provided by the actions of some of the mechanisms of the intestine.
With the help of peristalsis, feces enter the sigmoid colon, where they accumulate and are temporarily retained.
Stopping the further movement of feces in this part of the intestine occurs due to contractions of the muscles that are in the intestine.
Pushing out the contents of the intestine helps not only its own muscle layer, but also the abdominal muscles.
Additional help from another muscle group helps to push feces into the anal canal with constipation and various spasms. After a bowel movement, the organ is free for some time and does not fill up.
This part of the intestine has a strong influence on the work of the stomach. If there are any problems, then this affects the digestive process, the release of saliva and bile.
The brain also affects defecation: if a person is worried or tired, then this delays bowel movement.
Possible diseases
Since the structure of the intestine in the female and male body is different, there are also a lot of diseases that can be in this organ.
One of the most common diseases of the rectum is proctitis. In other words, inflammation of the mucosa.
This disease may be caused overuse spicy foods and spices, as well as constipation, during which stagnation of feces is observed.
Faeces can remain in the "pockets" between Morgagni's columns, gradually poisoning the body, which can also lead to congestive proctitis.
Inflammation of the rectal mucosa can begin after unsuccessful therapy with laser beams.
For example, if a person has a tumor in the pelvic region, then as a result radiotherapy may well develop proctitis.
Inflammation of the mucosa can also occur from hypothermia, hemorrhoids, cystitis, prostatitis, etc.
Proctitis is chronic and acute. The first type of pathology proceeds almost imperceptibly, accompanied by slight itching and burning in the anus.
Acute proctitis comes on suddenly and is characterized by high temperature, heaviness in the intestines, chills, burning in the intestines.
This type of proctitis occurs infrequently, with timely treatment perhaps enough fast recovery sick.
But the prognosis for chronic proctitis is more disappointing, because with this type of disease, exacerbations periodically occur.
Rectal prolapse is a pathology in which the wall of the organ falls out through the sphincter.
Most often this is observed in women who have undergone difficult childbirth, because after them the muscles of the anus can be significantly stretched and injured in a woman, tears are possible.
However, prolapse of the intestine also occurs in men. Usually this can happen due to changes in the muscles of the anus during aging, from previous operations on the intestines. Constipation can lead to pathology if a person regularly pushes for a long time in the toilet.
Usually the disease begins with constipation and other difficulties in defecation in childhood, but the first signs of the disease in adulthood are also possible.
With this pathology, a person begins itching in the anus, incontinence of feces, blood and mucus are released.
Diagnosis of rectal prolapse is by palpation. Also, the doctor may ask the patient to push - then part of the intestine becomes visible. If polyps are suspected, a colonoscopy may be performed.
For adults in such cases, only surgical intervention. During the operation, the ligaments of the intestine are strengthened for the patient.
If a person also complains of incontinence, then the muscles of the anus are additionally strengthened.
The operation, although rather big, can be carried out by almost everyone - even the elderly.
Quite often, prolapse of the intestine occurs along with the prolapse of the uterus in women. If a woman of advanced age or is not going to have children, then the uterus is cut out.
If bowel prolapse occurs young man without other health problems, they may prescribe conservative treatment which includes special physical exercise, strengthening the muscles of the anus, and a diet rich in essential vitamins.
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 is the uterus and posterior fornix 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. upper part 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 is towards 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. Physical activity 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 normal state and controlled 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 feces in a straight line 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.
transverse muscles arbitrary sphincter controlled by centers in 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 difficult process, adjustable reflex. 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 an 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 an accelerated withdrawal harmful substances from the body.
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