Root of the mesentery of the transverse colon. Transverse colon: its structure and types of disease. Diseases of the mesenteric process of the small intestine

The small intestine and ileum are combined under one term, since both sections are covered by peritoneum (specific tissue of the abdominal space) and are attached to the abdominal wall from the back using a special fold called the mesentery. Despite the lack of a common border, each section of the intestine has typical features. For example, the mesenteric part is attached to one of the edges of the small intestine, where the mesentery itself is attached. This intestinal extension is characterized by a large diameter, thickened walls, and a large number of choroid plexuses.

Mesenteric part of the small intestine.

What is the mesenteric part of the small intestine?

The mesentery in the intestines is usually understood as a special transverse section of the colon, tightly adjacent to the peritoneum at the back. On the mesenteric process in the intestines they are attached in the retroperitoneal space:

• transverse colon with large intestine - in the upper part of the appendix;
• small intestine - in the middle part;
• the rhizome of the mesentery ends at the sacrum.

The mesenteric parts are protected on each side by the connective tissues of the peritoneum. A large number of nerves, lymphatic vessels, arteries and veins pass through this section, through which the small, ascending, transverse, descending colon and appendix are supplied with nerve impulses and blood.

The main functions of the mesenteric process are blood supply and innervation of most organs in the abdominal space. Therefore, the mesenteric parts are often involved in pathological processes, such as:

• inflammation of the mesenteric process;
• cyst formation;
• intestinal tumorigenesis.

Location of the mesentery

The root of the mesentery of the small intestine is fixed at the posterior peritoneal wall. This section begins to the left of the second lumbar vertebra. The middle part is slightly inclined, progression occurs from top to bottom, from the left side to the right. The final destination is the transition point to the large intestine.

The mesenteric part reaches 200 ml in height. The distance of the top point from the navel is 80-100 mm above the navel. From the groin area, the lower part rises 100 mm. The length of the root is 230 mm.

The intestines with the mesenteric process are the most vulnerable places in the body, since they are practically unprotected from the inside and outside. The mesentery is slightly covered by the intestine, but this does not protect it from various pathologies.

Diseases of the mesenteric process of the small intestine

Under the influence of various factors, pathologies develop that lead to serious consequences affecting the mesenteric intestine.

Thrombosis with embolism are diseases of the digestive system. The formation of an embolus occurs in a vessel of any other organ. Then it is sent to the intestines along with the bloodstream. Since the intestinal vessels are quite thin, the embolus cannot pass further. For this reason, blockage occurs, neoplasms are formed, which lead to necrosis of the intestinal loops. Pathology can be caused by:

• endocarditis, defects, general failure and other heart diseases;
• varicose veins;
• atherosclerosis, phlebitis, aneurysm affecting blood vessels;
• hypertension;
• myocardial infarction;
• operations that increase thrombosis, for example, cesarean section, gastroenterostomy, splenectomy.

The extent and severity of the pathology depend on the location of the blockage and the type of damaged mesenteric vessel. When thrombosis forms in the upper part, the parts of the intestine that are thin are affected. With a timely response in the intestine, rapid normalization of functions is possible. The disease occurs more often in older people. If not treated in a timely manner, death is possible. Symptoms: severe abdominal pain, weakened pulse, weakness, vomiting, bloating, diarrhea with blood in the stool.

It is difficult to diagnose the disease due to the similarity of the clinical picture with other diseases, for example, appendicitis, ulcerative lesions, cholecystitis. If detected, emergency assistance is required with excision of the dead intestinal loop and removal of the blood clot.

The mesenteric rupture is characterized by its scale. The phenomenon is accompanied by damage to the integrity of other abdominal organs, in particular the intestines. In this way, the mesenteric part of the small intestine is injured due to closed or open internal mechanical damage. The pathology is accompanied by vascular defects, severe bleeding, followed by necrosis of the damaged part and nearby tissues. Isolated ruptures are difficult to diagnose. Treatment of the pathology is surgical and consists of ligation of blood vessels and removal of blood from the abdominal cavity. If the body is severely weakened, a blood transfusion is performed.

Cysts in the mesentery arise for various reasons and can have any size. Cysts are:

• mesothelial;
• intestinal;
• lymphatic;
• mixed;
• false.

Some of the neoplasms can be palpated in the umbilical area. When diagnosed by fluoroscopy and pyelography, the entire mesenteric part of the small intestine and the intestine itself are clearly visible, which helps to identify the early stages of the disease. The difficulty of treatment lies in the need to remove the entire mesenteric vessel or part of the intestine when removing the cyst due to the presence of large vascular plexuses in the organ. Complications often occur:

• low intestinal patency, rupture, volvulus;
• suppuration of the cyst with risk of rupture;
• internal bleeding.

The risk of arterial embolism or vein thrombosis during cyst formation is high due to impaired blood circulation in the mesentery. Blood clots form in the vessels. They slow down blood flow throughout the intestines.

Tumor formations in the mesenteric process.

They may be a malignant sarcoma or cancer, a benign fibroma, or a fibrolipoma. Their growth is not limited in size. Tumors can be easily palpated in the middle or right abdomen. There may be no symptoms. As they grow, they appear:

• sharp pain in the abdomen;
• weakness;
• decreased appetite;
• anorexia;
• short-term fever;
• nausea with vomiting.

Tumors are removed with or without part of the intestine, it all depends on its location and size. Mortality is common.

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The structure of the posterior abdominal wall is key to understanding the relationship between the large intestine and the rest of the abdominal organs. The outer boundary of the abdominal cavity is the intra-abdominal fascia, which covers the muscles of the posterior wall (Fig. 1). The large vessels and urinary structures pass between the intra-abdominal fascia and the posterior parietal peritoneum and are surrounded by the fascia intermedius (Gerota). Note the ureters running along the upper psoas muscles near the spine and crossing the bifurcations of the common iliac vessels.

During the formation of the omental bursa and rotation of the middle section of the primary intestine, the duodenum and pancreas lie on the deepest abdominal structures (vessels, ureters) (Fig. 2). As a result of fixation of the rotated colon to the underlying structures, two delta-shaped sections of fused fascia are formed on the right and left sides, and the root of the mesentery of the transverse and colon runs diagonally and crosses the second part of the duodenum and the pancreas (Fig. 3). The root of the mesentery of the sigmoid colon crosses the left iliac vessels and the ureter.

The mesentery of the transverse colon is shortened at the corners, but elongated in the center, which allows the transverse colon to hang down freely when the body is in an upright position (Fig. 4). The hanging distal part of the stomach is placed on this wide surface of the mesentery (Fig. 5). The gastrocolic ligament is formed from the anterior layers of the greater omentum, in which the gastroepiploic vascular arcades pass.

By viewing serial transverse sections of the abdominal cavity, one can better understand the anatomy and relative position of the large intestine (Fig. 6). As can be seen in the figure, the splenic angle is always (albeit to varying degrees) located above the hepatic angle. When introducing ports to mobilize the left intestine, one should take into account the special importance of isolating this particular area. In the figure, the transverse colon is pubescent, and the sigmoid colon is shortened and straightened, but the latter is often excessively elongated. Redundancy of any part of the intestine makes laparoscopic manipulation difficult.

Acute blockage of the vessels of the intestinal mesentery (in medical terminology - acute occlusion of the mesenteric vessels) is an acute disruption of blood flow in the vessels of the mesentery, which leads to a deterioration in the nutrition of the intestinal wall and the development of various pathological processes in it. The mesentery is a thin film of connective tissue that attaches the intestine to the abdominal wall and through which its blood vessels and nerves pass. Therefore, occlusion of the mesenteric vessels is fraught with severe disorders of the small and large intestines along its entire length.

Total information

Acute blockage of mesenteric vessels is considered an emergency pathology in gastroenterology. But in fact, it is dealt with in a surgical hospital, since circulatory disorders in the intestines lead to irreversible changes that require surgical intervention.

The degree of intestinal damage in acute occlusion of mesenteric vessels depends on factors such as:

• type of blockage;
• the level in the blood vessel at which it occurred;
• the presence of additional arterial pathways that can take on the function of a blood supplier in the event of blockage of other branches and compensate for the lack of blood supply (they are called collateral blood flow pathways).

Blockage of mesenteric vessels can be:

• arterial;
• venous;
• mixed (arteriovenous).

In 90% of all clinical cases of occlusion of mesenteric vessels, blockage occurs in the main trunk of one of the largest mesenteric arteries - the superior mesenteric artery - or its large branches. This artery plays a major role in the blood supply to the gastrointestinal tract. The inferior mesenteric artery can also be blocked, but the mentioned collateral branches are well developed, so blockage at any level is not so fraught.

Mesenteric veins are less likely to become clogged. Also, cases of mixed blockage of mesenteric (mesenteric) arteries and veins are not very common. With a mixed type of occlusion, chronic blockage of one vessel occurs first, and then, against its background, acute blockage of another.

note

Most often, this pathology is observed in men. It is mainly diagnosed over the age of 50 years.

Causes

Acute blockage of the vessels of the intestinal mesentery can be caused by:

• thrombus - a compacted blood clot;
• embolus - any biological substrate that is located in the lumen of a vessel, is not associated with it and can easily migrate with the bloodstream.

In most clinical cases, the mesenteric vessels are blocked by a thrombus.

Pathology rarely occurs due to the formation of a blood clot directly in the mesenteric vessels. For the most part, it is preceded by diseases of the cardiovascular system, as a result of which blood clots form, which then migrate into the mesenteric vessels, although there may be non-vascular causes of occlusion of the mesenteric arteries and veins. Most often this occurs with diseases and conditions such as:

The following can act as an embolus:

Development of the disease

Having entered the mesenteric vessel with the blood flow, the thrombus or embolus blocks its lumen.

Often the formation of a blood clot, which subsequently leads to blockage of the vessel, is preceded by the so-called Vikhrov triad:

• changes in the walls of the vessel;
• increased blood clotting;
• local (local) slowing of blood flow.

In some cases, even a small thrombus or embolus, which migrates freely in the vascular system with the blood flow, can at any time clog a vessel by unfolding in it.

Acute blockage of the mesenteric vessels of the intestine is manifested by a sharp disturbance in blood flow. It develops in the vascular areas above and below the blocked area. In response to irritation of the inner lining of the vessel, into which the edges of the thrombus or embolus “rest”, the vessel reacts with a spasm, which further aggravates the obstruction of blood in this part of the vascular system. Another aggravating factor is additional thrombus formation at the site of blockage. As a result of all these pathological processes, the supply of oxygen and nutrients to the intestinal tissues stops, an acute disturbance of its nutrition and ischemia (oxygen starvation) of the intestinal wall develops.

If no measures are taken to restore blood flow or if the thrombus (embolus) does not spontaneously slip out of the bottleneck of the vessel, destructive (destructive) changes in the intestinal tissues that are supplied with blood thanks to this vessel will very soon develop. Such changes are irreversible.

The most severe consequences of acute blockage of the mesenteric vessels are anemic (due to impaired blood flow) and hemorrhagic (due to minor hemorrhages) necrosis of the intestinal wall. Therefore, occlusion of mesenteric vessels is characterized by an extremely severe course and a high mortality rate.

Acute blockage of the mesenteric vessels of the intestine can occur in three forms - with compensation, subcompensation and decompensation of mesenteric blood flow. The difference between them is as follows:

• at compensation the intestinal wall suffers from short-term starvation, but then is anatomically and functionally restored completely. This may occur spontaneously or due to conservative therapy;
• at subcompensations mesenteric blood flow is robbed, intestinal tissues are partially supplied with blood and do not receive enough nutrients, which leads to the development of a number of intestinal diseases, but often non-critical and treatable. With subcompensation of mesenteric blood flow, gastroenteritis (oxygen starvation of the intestine, leading to deterioration of its functions), (inflammatory damage to the small intestine), (inflammation of the mucous membrane of the large intestine), including ulcerative diseases, and some other diseases may occur;
• during decompensation, mesenteric blood flow practically stops, which leads to necrosis of the intestinal wall, infection, development of diffuse purulent and the occurrence of a severe septic condition with a threat of death.

Symptoms

Acute blockage of the mesenteric vessels may not appear immediately - it may be preceded by so-called precursors of the disease (a similar principle is when precursors appear during a pre-infarction state, if blood flow in the vessels of the heart is disrupted). This depends on the degree of blood supply disruption. These precursor symptoms are called abdominal toad - these are:

• seizures
• persistent;
• pretty quick weight loss.

Characteristics of pain in abdominal angina:

Such signs should cause medical concern, since there is a risk of acute occlusion of the mesenteric vessels of the intestine.

But in most cases, blockage of the mesenteric vessels begins suddenly, without warning. Its clinical manifestations depend on the stage of the disease. There are three successively developing stages of occlusion of the mesenteric vessels of the intestine:

• ischemia;
• heart attack;

The ischemia stage develops in the first 6-12 hours from the moment of blockage. Its clinical manifestations are as follows:

• unbearable abdominal pain in the form of severe contractions . The patient cannot sit still, tries to alleviate his condition and for this purpose takes a forced position - curls up into a ball and brings his legs to his stomach;
• severe nausea with almost immediate vomiting. First, bile and streaks of blood (hereinafter referred to as blood clots) can be detected in the vomit. As the disease progresses, the vomit has a fecal odor;
• frequent loose stools in which . Such stool is also called ischemic (due to oxygen starvation) bowel movement.

The infarction stage develops within a period of 12-18 hours from the moment of blockage. Its clinical manifestations are as follows:

• pain felt at rest subsides to some extent, but pain increases when palpating the abdomen;
• the patient's general condition worsens;
• manifestations of diarrhea are reduced, stool is partially normalized.

The stage of peritonitis occurs 18-36 hours after the blockage. Its clinical manifestations are as follows:

Diagnostics

Symptoms of acute blockage of mesenteric vessels are quite pronounced; monitoring changes in complaints is especially helpful in diagnosis. Also important are details of the anamnesis (history of the disease), such as the acute onset of abdominal pain and the patient’s existing cardiovascular diseases. To confirm the diagnosis, physical (examination, palpation, percussion, auscultation of the abdomen), instrumental and laboratory diagnostic methods are used.

In the ischemic stage, physical examination data will be as follows:

Changes in the cardiovascular system are observed:

• an increase in blood pressure by an average of 60-80 units (the so-called Blinov symptom);
• the pulse becomes slower than normal.

At the stage of infarction, physical examination data will be as follows:

• upon examination, a further deterioration in the general condition of the patient is noted;
• upon palpation in the place where the affected intestine is projected, the pain increases. You can also feel an oblong cylindrical swollen formation with a dough-like consistency;
• upon percussion there is pain in the affected area;
• no significant changes are noted on auscultation.

• blood pressure returns to normal levels;
• the pulse begins to quicken.

In the stage of peritonitis, physical examination data will be as follows:

• During the examination, the patient’s serious condition is recorded. The skin is pale earthy in color, the tongue is extremely dry, covered with a white-dirty coating, the stomach does not take part in the act of breathing;
• on palpation - severe pain, the anterior abdominal wall is tense (surgeons characterize it as “like a board”), symptoms of peritoneal irritation are clearly visible;
• with percussion – severe pain even with slight tapping on the anterior abdominal wall;
• on auscultation, there are no peristaltic sounds due to the onset of paralytic intestinal obstruction.

Changes in the cardiovascular system are as follows:

• severe arterial hypotension;
• pronounced increase in heart rate.

To clarify the location of the lesion and other details, instrumental diagnostic methods are used such as:

Of the laboratory examination methods in the diagnosis of occlusion of mesenteric vessels, the most informative are:

• – the addition of infection and necrosis of the intestinal wall will be indicated by a significant increase in the number of leukocytes and ESR. The risk of thrombosis is also assessed by the number of platelets;
• – determine the amount of cholesterol in the blood, thereby obtaining an indirect opportunity to determine the condition of the inner surface of the blood vessels;
• – after analyzing its indicators, they evaluate the properties of the blood coagulation system and the ability to form blood clots.

Differential diagnosis

Symptoms characteristic of acute occlusion of mesenteric vessels can also be observed in other diseases, with which it is necessary to carry out a differential diagnosis of blockage of mesenteric vessels. These are pathologies such as:

• perforated and duodenal ulcer;
• spicy ;
• (dynamic and mechanical);
• spicy ;
• acute (calculous and non-calculous).

Treatment

If there are signs of acute inclusion of the mesenteric vessels of the intestine, the patient is urgently hospitalized in the surgical department.

The basis of treatment for this pathology is:

• conservative therapy;
• surgical intervention.

The operation must be performed as an emergency. The purpose of surgery is as follows:

• audit (inspection and evaluation) of the mesentery to check blood flow and intestines to assess its viability;
• elimination of the cause that provoked vascular obstruction;
• restoration of blood flow through the mesenteric vessels;
• resection (removal) of dead sections of intestine.

Resumption of blood flow (revascularization) through the mesenteric vessels is performed using methods such as:

• removal of a blood clot (thrombectomy);
• embolus removal (embolectomy);
• bypass - creation of bypass blood flow paths using a vascular prosthesis (superior mesenteric artery replacement). Performed in especially severe cases.

If necrosis has developed in the intestinal wall, then these sections of the intestine are excised. Excision is performed with the capture of healthy intestinal tissue, because the appearance of the affected intestinal segment does not correspond to the level of deterioration in blood flow (external changes may be delayed). In some cases, surgeons decide to perform a repeat laparotomy (after 24-48 hours) to monitor the condition of the intestine.

Conservative treatment begins at the stage of preparing the patient for surgery and continues during and after surgery. Conservative therapy is based on the following:

• antithrombotic drugs to prevent recurrent thromboembolism of mesenteric vessels;
• intensive infusion therapy - is carried out to restore the volume of circulating blood, improve blood supply to tissues and tissue metabolism (metabolism), stabilize the functioning of the cardiovascular system, and remove the patient from pain shock;
• – to prevent the development of infectious complications, and if they have already developed, to relieve them;
• Oxygen therapy is the supply of oxygen through a mask into the airways.

Prevention

The occurrence of acute occlusion of the mesenteric vessels of the intestine can be prevented if the sources of thrombus formation are promptly eliminated. First of all, this means identifying and treating diseases such as:

Clinical alertness is also necessary regarding blockage of blood vessels by emboli - first of all:

The prognosis for this disease is complex. If it is possible to restore blood flow in the mesenteric arteries during the first 4-6 hours from the onset of vascular blockage, then intestinal infarction can be avoided and its normal activity can be resumed.

As a rule, surgical treatment is carried out in the second and third stages of occlusion - mainly due to the late presentation of patients, as well as the time required to carry out diagnostic measures. Due to delayed assistance, the mortality rate is 80-90%. The prognosis worsens due to the underlying pathology, which contributed to the formation of a blood clot and blockage of the mesenteric vessels.

Mesentery of the intestine - layers of peritoneum, with the help of which the internal organs (stomach, large, small intestine and others) are attached to the posterior wall of the abdomen.

The mesentery has an extensive network of blood vessels, nerve endings and lymph nodes, which are involved in supplying the organ with necessary nutrients, transmitting nerve impulses and supporting the immunity of internal organs.

The structure of the mesentery

Some organs located in the peritoneal cavity have a serous membrane. The folds of peritoneum that surround the loops of the small and large intestines are called the mesentery. But it is worth noting that not all parts of the digestive tract have peritoneal layers.

For example, at the level of the duodenum they are completely absent, and the mesentery of the small intestine is most developed. The posterior portion of the mesentery, which is attached to the wall of the abdomen, constitutes the root of the mesentery. Its size is small and reaches approximately 16 cm.

The opposite edge, which affects the entire small intestine, is equal to the length of these two sections. Next, the mesentery goes to the intestinal loops and surrounds them in such a way that they are tightly fixed between the layers of the peritoneum.

What role does it serve?

The main function of the mesentery is to separate most of the organs from the posterior abdominal wall and prevent the organs from descending into the pelvis when the body is in an upright position. The vessels of the mesentery provide the intestinal walls with a sufficient amount of oxygen, which is simply necessary for normal functioning.

Nerve cells send impulses to the brain and receive them back. The lymph nodes located at the base of the mesentery provide the protective function of the entire intestine.

Diseases

Mesenteric infarction

Mesenteric infarction and intestinal infarction occur as a result of circulatory disturbances in the mesenteric vessels due to thrombosis or embolism. The main clinical manifestation of the pathology is severe pain in the navel area. However, it is worth noting that upon palpation the abdomen remains soft and less painful.

Over time, the pain subsides, and with complete necrosis of the intestinal wall, it disappears altogether, which interferes with a positive prognosis.

The patient's skin is pale, the tongue is dry and has a white coating. It happens that just a few hours after the onset of tissue necrosis, fluid effusion into the abdominal cavity (ascites) begins.

If you do not go to the hospital on time, the disease begins to progress and the person becomes lethargic and apathetic. Even if you begin to take the necessary measures after extensive necrosis, coma and convulsive seizures may occur. To confirm the diagnosis, specialists prescribe ultrasound of the abdominal organs, x-rays, and laparoscopy.

Surgery is considered the best way.

Treatment consists of removing all foci of necrosis

Mesenteric cyst

A benign thin-walled neoplasm that has neither a muscle layer nor an epithelial layer. Cysts appear between the 2 sheets of the mesentery of any part of the digestive system and are not associated with the intestines. The most common cyst is the mesentery of the small intestine.

The process of the appearance and growth of neoplasms takes a long time, so during this period the patient does not notice any manifestations. To make a correct diagnosis, palpation of the abdomen is performed, during which a mobile mesenteric tumor is clearly felt, painless. Cysts are treated only surgically.

Cancer

A malignant neoplasm that leads to tissue breakdown. The pathology is much less common than cysts. The clinical picture of tumors is similar to a cystic formation. The first symptoms begin to appear only when the tumor is large and compresses the internal organs.

Patients begin to complain of abdominal pain of varying intensity, nausea and vomiting, belching, and flatulence. Diagnosing oncology is quite problematic, but with the help of ultrasound and CT it is possible to identify the location of the tumor, its size, and consistency. Treatment of mesenteric cancer is surgical, chemotherapy and radiation.

Gap

It occurs against the background of abdominal trauma and is combined with a violation of the integrity of neighboring organs, in particular the small or large intestine. Mesenteric rupture occurs both with penetrating wounds and closed abdominal injuries.

The main symptom of the pathology is the development of shock in the first hours, then it weakens or is replaced by another sign - internal bleeding or the onset of peritonitis. The picture of bleeding begins with pallor of the skin and mucous membranes, the pulse weakens and gradually disappears, and a low content of hemoglobin and red blood cells will be noted in the general blood test.

It is very difficult to recognize a rupture using radiation and clinical methods

The only effective way is laparoscopy. During it, treatment is carried out (the hematoma is removed, the bleeding vessels are tied up, the damaged mesentery is sutured).

Inflammation

The inflammatory process as a separate pathology occurs extremely rarely. Most often it occurs against the background of peritonitis, since the serous membrane is involved in this disease. It is almost impossible to recognize inflammation of the mesentery, since the clinical picture can be varied.

The most common symptom of the pathology is pain in the navel area of ​​varying intensity. The mesenteric lymph nodes increase in size, swelling and redness of the inflamed area appears. Over time, the mesenteric tissue is replaced in places by connective tissue, turning into dense scars. As a result, the walls of the mesentery grow together and shrink.

Treatment of any disease is aimed at eliminating the inflammatory process. Several groups of drugs are used for therapy: antibiotics, antispasmodics and painkillers. In addition, a mandatory condition on the path to recovery is diet. In the case of a purulent process, surgical intervention with complete sanitation of the abdominal cavity is indicated.

MESENTERY (mesenterium) - a duplication of the peritoneum with nerves, blood and lymph, vessels, lymph, nodes and fatty tissue enclosed between its layers, passing from the abdominal wall to one or another organ of the abdominal cavity (Fig. 1 and color Fig. 6).

Rice. 1. Posterior wall of the abdominal cavity: 1 and 10 - v. cava Inf.; 2 - recessus omentalis sup.; 3 - pancreas; 4- root mesocolon transversum; 5 - flexura duodenojejunalis; 6 - radix mesenterii; 7 - root of mesocolon sigmoideum; 8 - mesorectum (BNA); 9- rectum; 11- aorta abdominalis; 12 - duodenum.

Rice. 6. Convolutions of the mesentery: 1 - hepar; 2 - cardia ventriculi; 3 - vesica fellea; 4 - pancreas; 5 - lien; 6 - pylorus; 7 - duodenum; 8 - mesenterium; 9 - colon ascendens; ί ο - colon descendens; 11 - ileum; 12 - appendix; 1 3 - colon sigmoideum; 1 4 - rectum; 15 - vesica urinaria.

The word "mesentery" is also used in a broader sense. Thus, they describe: B. tendons (mesotendineum), B. uterus (mesometrium), B. ovary (mesovarium) and B. fallopian tube (mesosalpinx).

Lat. the name of the mesentery of different organs is formed from the combination of meso- with the name of this organ. For example, B. small intestine - mesenterium, B. large intestine - mesocolon, B. uterus - mesometrium.

Comparative anatomy and embryology

B. intestines develops in animals that have a secondary body cavity. In the embryo, B. arises from the visceral leaves of the lateral plates of the ventral mesoderm. These leaves grow together above and below the primary gut and form two B.: dorsal and ventral. In vertebrates, the dorsal liver is predominantly preserved. The remains of the ventral liver in most vertebrates are represented by the falciform ligament of the liver. The embryo initially develops a common mesentery of the small and large intestines (mesenterium dorsale commune). As parts of this general B. at the end of organogenesis, the following remain: B. of the small intestine (mesenterium), B. of the appendix (mesoappendix), B. of the transverse colon (mesocolon transversum), B. of the sigmoid colon (mesocolon sigmoideum) and B. of the upper part rectum (mesorectum). In children, B. of the ascending (mesocolon ascendens) and descending (mesocolon descendens) colon is sometimes preserved.

Anatomy

The place of origin of the small intestine from the posterior wall of the abdominal cavity is called the root of the small intestine (radix mesenterii). The line of its attachment extends from the left side of the second lumbar vertebra to the right sacroiliac joint and is approx. 13-15 cm. However, this is only the most common option. The root attachment of B. is sometimes almost horizontal. Between these two extreme forms, various options for the location of the B. root are possible (Fig. 2). In children, the B. root reaches only the confluence of the common iliac veins. B. reaches its greatest width (17 cm) in two places: one on the border of the upper and middle third of the small intestine and the other - approx. 40 cm at its lower end.

In the B. of the small intestine there are branches of the superior mesenteric artery, which form 3-4 rows of arcade anastomoses. Straight vessels extend from the last row of arcades and go directly to the intestinal wall. The veins that drain blood from the small intestine run next to the arterial vessels of the small intestine and flow into the superior mesenteric vein. Lymphs and blood vessels of the small intestine are located along the blood vessels, interrupted in two or three rows of lymph nodes. The common collector of lymphatic pathways is the intestinal lymphatic trunk, which flows into the thoracic duct cistern at the level of the second lumbar vertebra. Nerve trunks enter B. from the superior mesenteric plexus.

The root of the B. transverse colon is located at the level of the first lumbar vertebra and runs from the middle of the right kidney to the anterior surface of the left kidney. The length of the B. root is about 20 cm, the width in the similar part reaches 10-12 cm. Between the leaves of the B. the middle colic artery passes, the edges, breaking up into arcuate branches, anastomose with the branches of the right colic artery in the area of ​​the hepatic inflection and with the branches of the left colonic artery in the area of ​​the splenic flexion. The veins of the B. transverse colon accompany the arteries of the same name and flow into the superior mesenteric vein. Lymph vessels follow the course of the blood vessels and are directed primarily to lymph nodes located at the root of the small intestine. Nerve branches from the superior mesenteric plexus pass through the B. of the transverse colon.

Rice. 7. Blood vessels and lymph nodes in the mesentery: 1 - nodi lymphatici mesenterici superiores; 2 - a. jejunalis; 3 - v. jejunalis; 4 - mesenterium; 5 - tunica mucosa; 6 - tunica muscularis (stratum circulare); 7 - tunica mussularis (stratum longitudinale); 8 - tunica serosa.

The root of the B. sigmoid colon is projected from the intersection of the psoas major muscle with the left sacroiliac joint and extends to the level of the anterior surface of the I-II sacral vertebrae. B. root length approx. 15 cm. In the thickness of B. there are sigmoid arteries and veins of the same name (tsvetn. Fig. 7). Lymph vessels follow the course of the blood vessels, interrupting in the lymph nodes of the B. itself, and flow into the lymph nodes located in the area of ​​​​the beginning of the inferior mesenteric artery. B.'s nerve branches originate from the inferior mesenteric plexus.

Pathology

As a developmental anomaly, the so-called sometimes occurs. common intestinal B. (mesenterium commune), which is a consequence of developmental delay at the early embryonic stage, when the entire intestine had one common dorsal B., attached to the posterior wall of the body cavity along the midline. Common B. is attached along the midline to the posterior abdominal wall, and all parts of the intestine are freely suspended on it, starting from the duodenum and ending with the rectum. In itself, this anomaly does not cause intestinal dysfunction and may not be accompanied by painful manifestations, but it predisposes to volvulus in various parts of the intestine. The presence of general intestinal B. can be established radiographically. Abnormalities in B.'s development explain the sometimes occurring B. holes; they usually have the shape of an irregular oval and are most often localized in the caudal part of the small intestine, less often in the middle, as well as in the transverse colon and sigmoid colon. Openings in the mesentery of the appendix, in the fatty pendants of the colon, and in the lesser omentum have also been described. With regard to the pathogenesis of such holes in B., it is assumed that in some places B.’s growth does not keep up with the rapid growth of the intestine; some authors believe that the holes are formed as a result of B.'s atrophy in places poorly supplied with blood vessels. Holes in the bowel of various parts of the intestine can be acquired (rupture due to abdominal bruises, incisions of the bowel left unsutured during surgical operations). Intestinal loops can penetrate into B.'s openings and become strangulated.

B.'s injuries are observed with abdominal bruises, strangulated hernias, and also with penetrating wounds of the abdominal cavity. A closed injury can affect the serous leaves of the bladder, neurovascular elements, and sometimes only the vessels passing through it when its serous leaves are intact. Damage can be varied, ranging from slight tears to complete separation of the bladder from the posterior wall of the abdominal cavity or separation of the intestinal loop from the bladder. Superficial small tears may not be accompanied by clinical manifestations; more significant ruptures are accompanied by rupture of blood vessels and cause internal bleeding (see) into the abdominal cavity. Separation of the intestinal loop from B. usually leads to its necrosis. Rupture of B.'s blood vessels while its serous leaves are intact leads to the development of B.'s hematoma and thrombosis of damaged vessels. If intestinal necrosis does not occur, then such a hematoma encystes and turns into a cyst with bloody contents; however, complications may appear in the future in the form of cyst rupture, suppuration or intestinal obstruction. Rupture of a cyst into the free abdominal cavity is accompanied by the development of peritoneal symptoms and requires emergency surgery; in very rare cases, a B. cyst may open into the intestinal lumen. Thrombosis of damaged veins of B. can spread to the main trunk of the mesenteric vein and further to the portal vein, which leads to death (see Pylephlebitis). In view of these complications, B.’s hematoma should be eliminated surgically as early as possible.

A special form of pathology is a rupture of lymphatic vessels, which can occur not only with abdominal bruises, but sometimes as a result of severe physical injury. work. Thin walls of lymphatic vessels can rupture under the pressure of the milky fluid, on the one hand, and strong tension of the abdominal press, on the other, resulting in symptoms of an acute abdomen, which requires urgent surgical intervention.

With penetrating wounds of the abdominal cavity, the abdominal cavity is often damaged; the edges should be carefully examined during laparotomy (see Abdomen, injuries).

Among the vascular diseases of B., embolism of B.'s arteries, endarteritis, atherosclerotic occlusion, thrombosis of arteries and veins, and their functional disorders in the form of periodic spasms are observed. Embolism of B.'s arteries can occur in diseases of the heart and aorta (endocarditis, aortic aneurysm); depending on the size of the embolus and the caliber of the obstructed vessel, various clinical phenomena develop, ranging from short-term pain and attacks of abdominal pain (see) and ending with extensive intestinal necrosis, accompanied by a severe picture of an acute abdomen (see). With timely diagnosed embolism of the mesenteric arteries (before the onset of intestinal necrosis), an embolectomy can be performed; when intestinal necrosis has already occurred, the only treatment. The measure is the resection of its dead area within healthy tissue. Less acute symptoms are observed with arterial thrombosis due to atheromatous ulcers and endarteritis. In these cases, vascular thrombosis is preceded for quite a long time by vague abdominal pain and functional intestinal disorders caused by ischemia of the intestinal wall (angina intestinalis). Narrowing of the large mesenteric vessels at this stage can be diagnosed by angiographic examination. At this stage, reconstructive surgery on the mesenteric arteries is indicated. When arterial thrombosis and intestinal necrosis occur, its resection within healthy tissue is indicated. B.'s vein thrombosis can lead to intestinal infarction and necrosis of a section of the intestine; however, the area of ​​necrosis is significantly smaller than when the corresponding artery is blocked.

Inflammatory changes in B. are common; bacteria from the intestine are able to penetrate the lymph, vessels and nodes of the intestine, but, apparently, with a healthy state of the intestinal wall they are neutralized and do not cause disease. When destructive changes appear in the intestinal wall, B.'s infection takes on a more active character, and mesenteric lymphangitis and lymphadenitis develop with an acute or subacute course.

An example of acute inflammation is inflammation of the appendix during appendicitis - mesenteriolitis, which can lead to the development of thrombophlebitis of the mesenteric veins and cause infected thrombosis of the intrahepatic branches of the portal vein - pylephlebitis. Treatment of this kind of mesenteritis consists of eliminating the primary focus in the intestine, if possible, excision of the affected veins and vigorous anti-inflammatory and antibacterial treatment.

Acute inflammation of lymph nodes, called “acute mesenteric lymphadenitis,” is often accompanied by a picture of an acute abdomen; during transsection, they are usually limited to establishing a diagnosis and then carry out conservative treatment. The pathogenesis of this disease is not always clear. More often, transmission of the infection probably occurs through the hematogenous route.

With hron, inflammatory changes in the intestines, as well as as a result of the general reaction of the lymph system of the body, for example, with tuberculosis, lymphogranulomatosis, hron, lymphadenitis B. are observed (see Mesadenitis).

An example of hron, inflammation of B. is tuberculous lymphadenitis of mesenteric lymph nodes. With this disease, along with the general manifestations of tuberculosis infection in the abdominal cavity, according to the course of B. of the small intestine, a conglomerate of dense enlarged lymph nodes is palpated. Treatment as for tuberculosis (see).

A peculiar form of hron, inflammation of B. is a wrinkling mesenteritis, more often observed in B. of the sigmoid colon (mesosigmoiditis), less often in B. of the ileum (mesoilitis): serous leaves lose their elasticity, become dense, thickened, whitish in color due to the growth of scar connective tissue; B.'s vessels are compressed, B. itself wrinkles and first limits the mobility of the corresponding part of the intestine, and then gives the intestinal loops an unusual position (or brings them together in the form of a double-barreled shotgun, or brings them closer and fixes them to the posterior abdominal wall). In the initial stages of the disease, you should try to establish the cause of mesenteritis, which is most often enteritis or colitis. In advanced stages of the disease, due to obstruction of patency, there may be indications for resection of the corresponding section of the intestine. In some cases, corrugating mesosigmoiditis is the cause of volvulus of the sigmoid colon.

B.'s cysts can reach very large sizes. Echinococcal cysts of B. are rare. An hydatid cyst can be suspected if echinococcus is present in other organs, as well as with a positive Kasoni reaction (see Echinococcosis). Treatment is surgical. In the B. of various parts of the intestine, dermoid, serous, and chylous cysts can also be found. They grow slowly and can reach enormous sizes without causing noticeable disorders; however, more often they are accompanied by a variety of subjective and functional disorders: a feeling of heaviness in the abdomen, sometimes attacks of pain, bloating, and intestinal obstruction may develop. Characteristic signs of B.'s cyst during clinical examination are: 1) its location in B.'s projection; 2) good mobility, especially in the perpendicular direction to the length of the intestine; 3) a strip of tympanitis over the tumor, giving a dullness to percussion sound (this is explained by the fact that the intestinal loop, sometimes swollen, passes along the anterior surface of the cyst); 4) in some cases, swaying is determined. To clarify the location of the cyst, X-ray examination of the intestine, angiography of the mesenteric arteries, and sometimes pneumoperitoneum are used. In case of B.'s cyst, surgical removal is indicated. If it is technically impossible to remove the cyst, the method of marsupialization is used (the cyst wall is sutured to the edges of the abdominal wall wound, the cyst cavity is tamponed) or the imposition of an anastomosis between the cyst and the jejunum,

Bibliography: Belyaev M.P. and Ponomarenko V.N. On the topography of the inferior mesenteric vein, in the book: Current issues, gastroenterol., ed. V. X. Vasilenko and A. S. Loginova, V. 5, p. 537, M., 1972; Efleev V.P. Anatomical and radiological study of the mesenteric arteries, Surgery, No. 8, p. 77, 1973; Multi-volume guide to surgery, ed. B.V. Petrovsky, vol. 7, JI., 1960; Sinelnikov R. D. Atlas of human anatomy, vol. 2, M., 1973; JoyeuxH. et Caporiccio A. Vascularisation des sb-lons, J. m6d. Montpellier, t. 7, p. 204, 1972; Ο Ή a g e K. Embriology and anatomy of the intestinal tract, Clin. Obstet. Gynec., v. 15, p. 415, 1972.

M. A. Egorov, V. I. Kozlov.