Large intestine. Topography, structure

The cecum is located in the right ileal fossa, 4-5 cm above the middle of the inguinal ligament. It can lie medial and lower, directly above the upper aperture of the small pelvis, or, conversely, it is located high, in the right subcostal area, under the right lobe of the liver. The base of the appendix is ​​projected at a point located between the right and middle third of the transverse line connecting the anterior superior iliacles of the ileum. The posterior wall of the cecum is attached to the parietal peritoneum in the region of iliac pits.

Left and bottom to the caecum abut the loops of the ileum.

The ascending colon (its posterior surface) is adjacent to the fascia that covers the iliac muscle, the square muscle of the waist, and to the renal fascia of the lower portion of the right kidney . The posterior wall of the intestine separates from the indicated fascia retroperitoneal tissue accompanying the colon. In front and left to the ascending colon are the loops of the small intestine, the large omentum.

The right (hepatic) bend of the colon is at the level of the costal cartilage and is adjacent to the lower surface of the right lobe of the liver, to the bottom of the gallbladder (to the right of it).

The transverse colon is located in the right hypochondrium region, in the epigastric region and in the left subcostal area, thus passing respectively the line connecting the end of the right X rib with the end of the left IX rib. The middle, sagging, part of the intestine can reach the level of the navel and even sink lower.

From the front, the transverse colon collides (separated by a large omentum) to the anterior abdominal wall. At the top it adjoins the lower surface of the right lobe of the liver, the gallbladder, the large curvature of the stomach and the spleen, at the bottom to the loops of the small intestine, at the back to the lower part of the duodenum and the pancreas. The transverse colon with its mesentery divides the abdominal cavity into two floors: the upper one, in which the liver, stomach and spleen lie, and the lower one, in which the whole mass of the loops of the small intestine lies.

The left (splenic) flexure of the colon is at the level of the IX costal cartilage or lying above the eighth intercostal space, 4 cm above the right (hepatic) curve; It is adjacent to the lower edge of the spleen and behind - to the left kidney.

The descending colon at the top is adjacent to the anterior surface of the left kidney. Below it is located at the fascia, which covers the square muscle of the waist, the transverse abdominal muscle and the iliac muscle. Like an ascending one, the descending colon is separated from the fascia by a loose retroperitoneal cellulose. The upper part of it is directed slightly obliquely to the right, down and anteriorly, and on the further extension - vertically downwards and anteriorly.

In front, the descending colon is covered with loops of the small intestine.

Sigmoid colon is located in the left ileum and in the upper part of the pelvic cavity; Depending on the width of the mesentery, it can pass beyond the middle plane of the abdominal cavity to the right half of the abdomen and be directed upward to the mesentery of the transverse colon. Behind, through the peritoneum, the sigmoid colon adjoins the iliac and lumbar muscles, and also to the common iliac vessels and ureter .

The rectum, as indicated, with its pelvic part lies in the recess formed by the sacrum and coccyx. At the back, it adjoins the rump, from the side and from below - to the muscles of the pelvic diaphragm.

In men in front (and above) at the level of the pelvic, covered with the peritoneum to the rectum, there are loops of the small intestine, the bladder , and in women - the body of the uterus and below - the uppermost part of the posterior wall of the vagina.

On the sides of the pelvic part of the rectum are peritoneal pararectal folds.

In front of the extraperitoneal portion of the rectum, the peritoneal-perineal fascia in the men are located: in the middle - the posterior wall of the bladder and below - the posterior surface of the prostate gland, laterally - the right and left seminal vesicles, the ampulla of the vas deferens.

In women to the anterior wall of the extraperitoneal portion of the rectum, the posterior vaginal wall adjoins, separated by a connective tissue rectal-vaginal septum, septum rectovaginale.

Innervation: colon - plexus entericus (plexus submucosus, myentericus, subserosus), in the formation of which participates plexus mesenterici superior et inferior (sympathetic plexus), and parasympathetic from n. Vagus; Rectum - similar plexus, forming plexus rectalis superior, medius and inferior, and parasympathetic from nn. Splanchnici pelvini. M. sphincter ani externus is innervated by n. Pudendus.

Blood supply: colon - a. Iliocolica, aa. Cecales anterior and posterior, a. Appendicularis, aa. Colici dextra et media (branches a. Mesenterica superior), a. Colica sinistra, aa. Sigmoideae, a. Rectalis superior (branches a. Mesenterica inferior); Rectum - a. Rectalis superior (branch a. Mesenterica inferior), aa. Rectales media et inferior (branch of iliaca interna). Venous blood flows along the veins of the same name in v. Portae; From the middle and lower parts of the rectum - in v. Iliaca interna. Lymph from the large intestine is sent to various groups of lymph nodes: from the caecum and the appendix to the nodi lymphatici ileocolici prececalis, appendiculares; From all parts of the colon - to nodi lymphatici mesocolici et mesenterici inferiores (sigmoidei, rectales superiores); From the middle and lower parts of the rectum to the nodi lymphatici rectales superiores et iliaci interni (sacrales), pararectales et sacrales.

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