home Calculators The superior mesenteric artery arises from. Superior mesenteric vein. The structure of the inferior mesenteric branch

The superior mesenteric artery arises from. Superior mesenteric vein. The structure of the inferior mesenteric branch

Superior mesenteric artery, a. mesenterica superior, is a large vessel that starts from the anterior superficial aorta, slightly below (1-3 cm) of the celiac trunk, behind the pancreas. Coming from under the lower edge of the gland, the superior mesenteric artery goes down and to the right. Together with the superior mesenteric vein located to the right of it, it lies on the anterior surface of the horizontal (or ascending) part of the duodenum, crosses it across, immediately to the right of the flexura duodenojejunalis. Having reached the root of the mesentery of the small intestines, the superior mesenteric artery penetrates between the leaves of the latter, forming an arch convex to the left, and reaches the right iliac fossa. Along its course, the superior mesenteric artery gives off the following branches: to the small intestine (with the exception of the upper part of the duodenum) , cecum with a vermiform appendix, ascending and partially to the transverse colon. The following arteries depart from the superior mesenteric artery.

Inferior pancreaticoduodenal artery, a. pancreatico-duodenalis inferior (sometimes not single), originates from the right edge of the initial section of the superior mesenteric artery, goes down and to the right along the anterior surface of the pancreas, bending around its head along the border with the duodenum. The inferior pancreaticoduodenal artery gives branches to the pancreas and
Intestinal arteries, numbering up to 15, depart sequentially one after another from the convex part of the arch of the superior mesenteric artery. Intestinal arteries are directed between the layers of the mesentery to the loops of the jejunum and ileum - these are the jejunal arteries and ileal arteries, aa.. jejunales et aa. ilei. On its way, each branch is divided into two trunks, which anastomose with the same trunks formed from the division of neighboring intestinal arteries. Such anastomoses look like arcs or arcades. New branches extend from these arcs, which also divide, forming arcs of the second order, somewhat smaller in size. From the arches of the second order, arteries again depart, which, dividing, form arches of the third order, etc. From the last, most distal, series of arches, straight branches extend directly to the walls of the loops of the small intestines. In addition to intestinal loops, these arches give rise to small branches that supply blood to the mesenteric lymph nodes.
Ileocolic artery, a. ileocolica, arises from the cranial half of the superior mesenteric artery, to the right of the root of the mesentery of the small intestine. Heading to the right and downward under the parietal peritoneum of the posterior abdominal wall to the end of the ileum and to the cecum, the ileocolic artery divides into two branches supplying blood to the cecum, the beginning of the colon and the terminal ileum.

Anterior and posterior cecal arteries, aa.. cecales anterior et posterior, heading to the corresponding surfaces of the cecum.
The ileal branch is a continuation of a. ileocolica, goes down to the ileocecal angle, where, connecting with the terminal branches of aa.. ilei, it forms an arc from which branches extend to the terminal section of the ileum.
The colon branch goes to the right towards the ascending colon. Before reaching the medial edge of this colon, it is divided into two branches, one of which, the ascending branch, g. ascendens, rises along the medial edge of the ascending colon and anastomoses (forms an arch) with a. Colica dextra; the other branch descends along the medial edge of the colon and anastomoses (forms an arch) with a. ileocolica. Branches extend from these arches, supplying blood to the ascending colon and cecum, as well as the appendix through the appendix artery, a. appendicularis.

Right colon artery, a. colica dextra, departs from the right side of the superior mesenteric artery in its upper third, at the level of the root of the mesentery of the transverse colon, and goes almost transversely to the right, to the medial edge of the ascending colon. At some distance from the ascending colon, the right colon artery divides into ascending and descending branches. The descending branch connects to branch a. ileocolica, and the ascending branch anastomoses with the right branch of a. Colica media. From the arches formed by these anastomoses branches extend to the wall of the ascending colon, to the flexura
Middle colon artery, a. colica media, departs from the initial section of the superior mesenteric artery, heading forward and to the right between the leaves of the mesentery of the transverse colon, and is divided into two branches: right and left

The superior mesenteric artery (a. mesenterica superior) is a large vessel that supplies blood to most of the intestine and the pancreas. The origin of the artery varies within the XII thoracic - II lumbar vertebrae. The distance between the orifices of the celiac trunk and the superior mesenteric artery varies from 0.2 to 2 cm.

Coming from under the lower edge of the pancreas, the artery goes down and to the right and, together with the superior mesenteric vein (to the left of the latter), lies on the anterior surface of the ascending part of the duodenum. Descending along the root of the mesentery of the small intestine towards the ileocecal angle, the artery gives off numerous jejunal and ileal arteries, which pass into the free mesentery. The two right branches of the superior mesenteric artery (ileocolic and right colon), heading to the right part of the colon, together with the veins of the same name, lie retroperitoneally, directly under the peritoneal layer of the bottom of the right sinus (between the parietal peritoneum and Toldt’s fascia). Regarding the syntopy of various parts of the trunk of the superior mesenteric artery, it is divided into three sections: I - pancreas, II - pancreas-duodenal, III - mesenteric.

The pancreatic section of the superior mesenteric artery is located between the legs of the diaphragm and, heading anterior to the abdominal aorta, pierces the prerenal fascia and Treitz's fascia.

The pancreatic-duodenal section is located in a venous ring formed from above by the splenic vein, below by the left renal vein, on the right by the superior mesenteric vein, and on the left by the inferior mesenteric vein at the place of its confluence with the splenic vein. This anatomical feature of the location of the second section of the superior mesenteric artery determines the cause of arterio-mesenteric intestinal obstruction due to compression of the ascending part of the duodenum between the aorta at the back and the superior mesenteric artery at the front.

The mesenteric section of the superior mesenteric artery is located in the mesentery of the small intestine.

Variants of the superior mesenteric artery are combined into four groups: I - branching of branches usual for the superior mesenteric artery from the aorta and celiac trunk (absence of the trunk of the superior mesenteric artery), II - doubling of the trunk of the superior mesenteric artery, III - branching of the superior mesenteric artery by a common trunk with the celiac artery, IV - the presence of supernumerary branches extending from the superior mesenteric artery (common hepatic, splenic, gastroduodenal, right gastroepiploic, right gastric, transverse pancreatic, left colon, superior rectal) [Kovanov V.V., Anikina T.I., 1974].

Visceral branches: middle adrenal and renal arteries

Middle adrenal artery (a. supra-renalis media) - a small paired vessel extending from the side wall of the upper aorta, slightly below the origin of the superior mesenteric artery. It goes outward, towards the adrenal gland, crossing transversely the lumbar pedicle of the diaphragm. It may originate from the celiac trunk or from the lumbar arteries.

Renal artery (a. renalis) - paired, powerful short artery. Starts from the lateral wall of the aorta almost at a right angle to it at the level I-II lumbar vertebra. The distance from the origin of the superior mesenteric artery varies within 1-3 cm. The trunk of the renal artery can be divided into three sections: periaortic, middle, perinephric. The right renal artery is slightly longer than the left because the aorta lies to the left of the midline. Heading towards the kidney, the right renal artery is located behind the inferior vena cava and crosses the spine with the thoracic lymphatic duct lying on it. Both renal arteries, on the way from the aorta to the renal hilum, cross the medial legs of the diaphragm in front. Under certain conditions, variations in the relationship of the renal arteries with the medial crura of the diaphragm can cause the development of renovascular hypertension (abnormal development of the medial crura of the diaphragm, in which the renal artery appears posterior to it). Except

In addition, the abnormal location of the renal artery trunk anterior to the inferior vena cava can lead to congestion in the lower extremities. From both renal arteries, thin inferior suprarenal arteries extend upward and ureteric branches extend downward (Fig. 26).

Rice. 26. Branches of the renal artery. 1 - middle adrenal artery; 2 - inferior adrenal artery; 3 - renal artery; 4 - ureteral branches; 5 - posterior branch; 6 - anterior branch; 7 - artery of the lower segment; 8 - artery of the lower anterior segment; 9 - artery of the upper anterior segment; 10 - artery of the upper segment; 11 - capsular arteries. Quite often (15-35% of cases reported by different authors) accessory renal arteries are found. All their diversity can be divided into two groups: arteries entering the hilus of the kidney (accessory hilus) and arteries penetrating the parenchyma outside the hilum, often through the upper or lower pole (additional polar or perforating). The arteries of the first group almost always arise from the aorta and run parallel to the main artery. In addition to the aorta, polar (perforating) arteries can also arise from other sources (common, external or internal iliac, adrenal, lumbar) [Kovanov V.V., Anikina T.I., 1974].

Acute disturbance of mesentary circulation

Etiology.

Acute disturbance of mesentary circulation may be caused by embolism or thrombosis of mesentary vessels.
Emboli occur due to blockage of blood vessels by a blood clot.
Thrombosis is a blockage of blood vessels by a clot formed in situ. Thrombosis is promoted by abdominal trauma, a drop in blood pressure, prolonged mesentary spasm, vascular damage by atherosclerosis, nonspecific aortoarteritis, compression of vessels from the outside (by a tumor), and hypercoagulation.

Anatomy.

Superior mesenteric artery- supplies blood to almost the entire small intestine (except for the initial part of the duodenum), the cecum, the ascending colon and half of the transverse colon. It extends 1.25 cm below the celiac trunk. Crosses the splenic vein and pancreas. Then it goes in front of the processus uncinatus of the head of the pancreas and the lower part of the duodenum, descends between the layers of the mesentery into the right iliac fossa, where it anastomoses with its own branch - a. ileocolica. The vein that runs next to it lies to its right.
Its branches:
- a. pancreaticoduodenalis inferior. It departs at the level of the upper edge of the lower part of the duodenum and goes to the right between the head of the pancreas and the intestinal wall. Then it anastomoses with the superior pancreatic-duodenal artery. It supplies the head of the pancreas, the descending pancreas and the lower part of the duodenum.
- aa. intestinales. Their number is usually 12-15. They run parallel to each other, then each branch divides into two and anastomose with each other, forming arches convexly directed towards the intestine.
- a. ileocolica. It goes down and to the right behind the mesentery to the right iliac fossa. It gives two branches - the lower, anastomosing with the end of the superior mesenteric artery, and the upper, anastomosing with the right colic artery. The lower branch gives branches to the ileum, caecum, ascending colon and appendix.
- a. Colica dexter. It goes to the right behind the mesentery. Gives rise to a descending branch that anastomoses with a. ileocolica, and ascending, which anastomoses with a. Colica media.
- a. Colica media. Exits slightly below the pancreas. It runs in the mesentery of the transverse colon. It gives rise to the right (anastomoses with a. colica dexter) and left (anastomoses with a. colica sinister, which arises from the inferior mesenteric artery) branches.

Inferior mesenteric artery- extends 3-4 cm above the division of the aorta, at the lower edge of the lower part of the duodenum. It supplies the left half of the transverse colon, the descending colon, the sigmoid colon, and most of the rectum. First it comes in front of the aorta, then to the left. Then it descends into the pelvis, where it turns into the superior hemorrhoidal artery, which runs in the mesentery of the sigmoid colon and ends at the upper part of the rectum.
Its branches:
- a. colica sinist ra .
- aa. sigmoideae - 2-3 arteries.
- a. haemorrhoidalis superior.

Pathogenesis.

With embolism, rapid intestinal necrosis occurs (after 4-5 hours) with perforation and the development of peritonitis.
With thrombosis, pathomorphological changes develop more slowly, since a network of collaterals is formed in patients with a previous disease.
When the mesentary veins are blocked, hemorrhagic necrosis develops.

Pathological anatomy.

There are three stages of pathomorphological changes occurring in the intestine:
1). Ischemia (if venous outflow is impaired - hemorrhagic impregnation).
2). Heart attack (gangrene, necrosis).
3). Peritonitis.
Morphologically, hemorrhagic, anemic and mixed myocardial infarction are distinguished.

The extent of intestinal damage depends on the location of the embolus or thrombus. The superior mesentary artery has three segments:
I - from its mouth to the origin of a.colica media. Necrosis of the entire small intestine occurs, and in half of the cases, the cecum and right half of the transverse intestine.
II - from the origin of a.colica media to the level of origin of a.ileocolica. Necrosis of the terminal portion of the jejunum and the entire ileum occurs.
III - distal to a.ileocolica. Only the ileum is affected.

Thrombosis mainly affects the superior mesenteric artery.
Necrosis of the left half of the colon due to thrombosis of the inferior mesenteric artery is very rare. This is due to the fact that the inferior mesenteric artery anastomoses with arteries from the internal iliac artery system (rectal, genital) and with the superior mesenteric artery. Nutrition of the intestine is provided by the development of collaterals. Infection of the descending colon develops with concomitant, and clinically significant, occlusive-stenotic lesions of the superior mesenteric artery.

Emboli also mainly affect the superior mesenteric artery (more than 90%), because it extends at a right angle (the celiac trunk and the inferior mesenteric extend at a right angle).

Classification.

I. By type of violation:
1). Occlusal:
a) embolism
b) arterial thrombosis
c) vein thrombosis
d) covering the mouths of arteries from the aorta due to atherosclerosis and thrombosis.
e) vascular occlusion during dissecting aortic aneurysm (switch-off symptom)
e) compression of blood vessels by tumors
g) ligation of blood vessels
2). Non-occlusive
a) with incomplete occlusion of the artery
b) angiospastic
c) associated with centralization of hemodynamics.

II. By stages of the disease:
1). Stage of ischemia.
2). Stage of heart attack.
3). Stage of peritonitis.

III. With the flow:
1). With compensation of mesentary blood flow, complete restoration of intestinal function is observed.
2). With subcompensation of mesentary blood flow, intestinal viability is maintained due to collaterals.
3). With decompensation of mesentary blood flow, intestinal infarction occurs.

Clinical picture.

The most typical symptoms are:
1). Abdominal pain. The nature of the pain is cramping or constant. The localization of pain varies depending on the level of vascular damage.
The pain is most intense in the stage of ischemia, in the stage of infarction it is somewhat dulled, then, with peritonitis, it intensifies again.
2). Nausea and vomiting. They are reflexive in nature.
3). Chair. There can be both diarrhea and intestinal obstruction; on this basis, two forms of stroke are distinguished. Usually there is frequent loose stool mixed with blood.
Acute disruption of mesenteric circulation is accompanied by intestinal obstruction. Therefore, some authors consider it one of the types of intestinal obstruction.

Diagnostics.

Intestinal peristalsis weakens and then disappears.
During digital examination of the rectum, dark blood is released.
X-ray - swollen intestinal loops with a horizontal fluid level (signs of intestinal obstruction). However, inflated loops easily change their position on the lateroscope. Radiography recognizes intestinal obstruction; it is not essential in recognizing stroke.
Ultrasound - reveals signs of intestinal obstruction, free fluid in the abdominal cavity. The main purpose is to exclude other pathologies of the abdominal cavity.
Laparoscopy.
Angiography. The most accurate diagnostic method. It is believed that angiography must be performed if stroke is suspected. It is necessary to identify patients with non-occlusive mesentary ischemia, since they are not candidates for surgery (they require treatment with vasodilators).
CT is gradually replacing angiography in diagnosing stroke.

D/diagnostics.

ACVA is differentiated primarily from mechanical intestinal obstruction, acute pancreatitis, acute cholecystitis, acute appendicitis, perforated gastric and duodenal ulcers.

Is it possible to distinguish stroke and mechanical intestinal obstruction before laparoscopy and angiography?

D/diagnosis of arterial and venous circulatory disorders?

Treatment.

If the intestinal loops are viable, embolism or thrombectomy is performed.
In the presence of a local occlusive-stenotic process, reconstructive surgery is performed - endarterectomy or aortomesenteric bypass (prosthetics).
In case of gangrene, the intestine is resected within healthy tissue. If the demarcation line is unclear, an enterostomy is performed (since if an anastomosis is performed, the sutures may fail).
In doubtful cases of bowel viability, revascularization is done first and then the bowel is looked at.
In patients with total damage to the intestine, surgery is limited to revision of the abdominal organs.
If there is a high probability of non-viable tissue remaining in the abdominal cavity, a repeat laparotomy (laparoscopy) is performed.

Superior mesenteric artery, a. mesenterica superior, with a diameter of about 9 mm, departs from the abdominal aorta at an acute angle at the level of the first lumbar vertebra, 1-2 cm below the celiac trunk. First it goes retroperitoneally behind the neck of the pancreas and the splenic vein.

Then it comes out from under the lower edge of the gland, crosses the pars horizontalis duodeni from top to bottom and enters the mesentery of the small intestine. Having entered the mesentery of the small intestine, the superior mesenteric artery runs in it from top to bottom from left to right, forming an arcuate bend, convexly directed to the left.

Here, branches for the small intestine extend from the superior mesenteric artery to the left, ah. jejunales etileales. From the concave side of the bend, branches for the ascending and transverse colon extend to the right and upward - a. colica media and a. Colica dextra.

The superior mesenteric artery ends in the right iliac fossa with its terminal branch - a. ileocolica . The vein of the same name accompanies the artery, being to the right of it. A. ileocolica supplies the final section of the ileum and the initial section of the colon.

Branches, a. mesentericae superioris:

a) a.pancreatieoduodeiialis inferior goes to the right along the concave side of the duodeni towards aa. pancreaticoduodenales superiores;

b) ah. intestinales- 10-16 branches that extend from a. mesenterica superior to the left side to the jejunum (aa. jejundles) and ileum (aa. ilei) intestine; along the way they are divided dichotomously and adjacent branches are connected to each other, which is why it turns out along aa. jejunales three rows of arcs, and along aa. ilei - two rows. The arches are a functional device that ensures blood flow to the intestines with any movements and positions of its loops. Many thin branches extend from the arches, which encircle the intestinal tube in a ring;

V) a. ileocolica it extends from a.r mesenterica superior to the right, supplying the lower portion of the intestinum ileum and the cecum with branches and sending it to the vermiform appendix a. appendicularis, passing behind the final segment of the ileum;

G) a. Colica dextra goes behind the peritoneum to the ascending colon and near it is divided into two branches: ascending (goes up to meet a. colica media) and descending (descends to meet a. ileocolica); branches extend from the resulting arches to the adjacent parts of the colon;

d) a. colica media passes between the leaves of the transverse colon and, having reached the transverse colon, is divided into right and left branches, which diverge in the corresponding directions and anastomose: the right branch - with a. colica dextra, left - with a. Colica sinistra.

Embolism of the superior mesenteric artery manifests itself as an acute onset of intense abdominal pain, usually localized in the umbilical region, but sometimes in the right lower quadrant of the abdomen. The intensity of pain often does not correspond to the data obtained from an objective examination of such patients. The abdomen remains soft upon palpation, or there is only slight soreness and tension in the muscles of the anterior abdominal wall. Intestinal peristalsis is often heard. Patients with superior mesenteric artery embolism often experience nausea, vomiting, and often diarrhea. In the early stages of the disease, stool examination reveals a positive reaction to occult blood, although, as a rule, there is not a large amount of blood in the stool.

A careful history of the disease can suggest the cause of the embolism. Classically, such patients always have signs of diseases of the cardiovascular system, most often atrial fibrillation, recent myocardial infarction or rheumatic lesions of the heart valves. A careful history often reveals that patients have previously had episodes of embolism, both in the form of strokes and peripheral arterial embolism. Angiography can identify the following emboli localization options:

Mouth (5.2%)

– the blood supply to the entire small intestine and the right half of the colon is disrupted

I segment (64.5%) – the embolus is localized to the origin of the a.colica media

– as well as when the embolus is localized at the mouth of the superior mesenteric artery, the blood supply to the entire small intestine and the right half of the colon is disrupted

II segment (27.6%) – the embolus is localized in the area between the points of origin of a.colica media and a.ileocolica

– the blood supply to the ileum and ascending colon to the hepatic flexure is disrupted

III segment (7.9%) – the embolus is localized in the area below the origin of the a.ileocolica

– blood supply to the ileum is disrupted

Combination of segment I embolism with occlusion of the inferior mesenteric artery

– blood supply to the entire small and large intestine is disrupted

Treatment. A large number of conservative treatments have been proposed for the treatment of superior mesenteric artery embolism. Although conservative treatment methods are sometimes successful in patients with acute embolism of the superior mesenteric artery, the best results are observed with surgical intervention. After laparotomy, the superior mesenteric artery is usually opened in a transverse direction at its origin from the aorta behind the pancreas. An embolectomy is performed, and once blood flow is restored through the superior mesenteric artery, the small bowel is carefully examined to determine its viability. To identify irreversible ischemic changes in the intestinal wall, a fairly large number of different tests have been proposed. Most often, a routine examination of the intestine is performed, which is often quite sufficient. The final conclusion about the condition of the intestinal wall is made after the intestine is warmed for 30 minutes either by lowering it into the abdominal cavity or by covering it with napkins moistened with warm saline solution. If there are signs of necrosis, intestinal resection is performed with end-to-end interintestinal anastomosis using a stapler. After the operation, the patient is sent to the intensive care unit. Sometimes, in patients who have undergone intestinal resection due to its necrosis due to acute embolism of the superior mesenteric artery, a second operation is performed after 24 hours, the so-called in order to examine the anastomosed edges of the intestine and ensure their viability. During the first operation, some surgeons prefer not to perform an interintestinal anastomosis, but suture both ends of the intestine using staplers. During reoperation, if a viable intestine is present, an interintestinal anastomosis is performed.

There are several reasons for the relatively high mortality rate after embolectomy from the superior mesenteric artery. Such patients often have very severe cardiovascular diseases that do not allow them to undergo major surgical interventions. Sometimes the diagnosis of embolism of the superior mesenteric artery is made late, which leads to the development of extensive intestinal necrosis. Systemic purulent-septic complications and enteral insufficiency due to resection of a large section of intestine also aggravate the condition of patients and often lead to death.