Peritoneum

Peritoneum (peritoneum) is a thin serous plate (membrane) lining the abdominal cavity and covering many of the organs located in it.

The peritoneum, attached to the internal organs, covering partially or completely many of them, is called the peritoneum viscerale (peritoneum) peritoneum. The peritoneum, which lines the abdominal wall, is called the parietal peritoneum parietale.

Limited abdominal space of the abdominal cavity - a narrow gap between the leaves of the peritoneum is called the peritoneal cavity (cavitas peritonei). Below the peritoneal cavity descends into the cavity of the pelvis. In men, the peritoneal cavity is closed, in women it communicates with the external environment through the abdominal orifices of the fallopian tubes, the uterine cavity and the vagina. In the peritoneal cavity there is a small amount of serous fluid, which moistens the peritoneum and ensures free sliding of each other adjoining organs.

The peritoneum, passing from the organ to the organ, forms ligaments (folds). Two sheets of peritoneum, going from the back wall of the peritoneal cavity to the organ, form a mesentery of this organ.

Between the leaves of the mesentery are the vessels and nerves. The line of the mesentery on the back wall of the abdominal cavity is called the mesentery root.

The peritoneum is formed by several alternating layers of collagen and elastic fibers covered from the peritoneal cavity by flat (mesothelial) cells. The surface area of the peritoneum is 1.7 m. The peritoneum performs an integumentary, protective function, contains immune structures (lymphoid nodules), adipose tissue (fat depot). The peritoneum, through ligaments and mesenteric glands, fixes the internal organs.

The ratio of the peritoneum to the internal organs is not the same. Zabrjushinno (retro, or extraperitoneally) are located kidneys, adrenals, ureters, most of the duodenum, pancreas, abdominal aorta, inferior vena cava. These organs are covered by the peritoneum on one side (front). The organs covered by the peritoneum on three sides, in relation to it, are arranged meso- peritoneally (ascending and descending colon, middle third of the rectum). The organs that are covered by the peritoneum on all sides occupy the intraperitoneal (intraperitoneal) position. This group of organs includes the stomach, the lean and ileum, the transverse and sigmoid colon, the upper part of the rectum, the spleen, and the liver.

Covering the anterior abdominal wall, the parietal peritoneum passes to the diaphragm at the top, along the lateral walls of the abdominal cavity, at the bottom - to the lower wall of the pelvic cavity. There are 5 folds on the anterior abdominal wall in the pelvic region. Unpaired middle umbilical fold (plica umbilicalis mediana) goes from the tip of the bladder to the navel, it contains a peritoneum overgrown urinary duct. The paired median umbilical fold (plica umbilicalis medialis) basically consists of an overgrown umbilical artery. The paired lateral umbilical fold (plica umbilicalis lateralis) is formed by the lower epigastric artery, also covered by the parietal peritoneum. Between the folds are pits - weak spots in the anterior abdominal wall (areas of possible formation of inguinal hernias). Above the bladder on the sides of the median umbilical fold are the right and left nadpuzyrnye fossa (fossae supravesicales dextra et sinistra). Hernias are not formed here. Between the medial and lateral umbilical folds is located on each side of the medial groin (fossa inguinalis medialis). Each such fovea corresponds to the superficial ring of the inguinal canal. Outside the lateral umbilical fold there is a lateral inguinal fossa (fossa inguinalis lateralis). In the lateral inguinal cavity there is a deep ring of the inguinal canal.

The parietal peritoneum of the anterior abdominal wall above the navel forms a fold - a crescent ligament of the liver (lig.falciforme, s.hepatis). From the abdominal wall and diaphragm this ligament goes down to the diaphragmatic surface of the liver, where both of its leaflets pass into the visceral cover (peritoneum) of the liver. In the free lower (anterior) edge of the crescent ligament there is a round ligament of the liver, which is a overgrown umbilical vein. Sheets of crescent ligament from the back diverge in the sides and pass into the coronary ligament of the liver. The ligamentous ligament (lig.coronarium) is located frontally and represents the transition of the visceral peritoneum of the diaphragmatic surface of the liver into the parietal peritoneum of the posterior wall of the peritoneal cavity. Along the edges, the coronary ligament widens and forms the right and left triangular ligaments (ligg.triangularia dextra et sinistra). The visceral peritoneum of the lower surface of the liver covers the gallbladder from the lower side. From the lower surface of the liver, from the area of its gates, the visceral peritoneum in the form of two leaves goes to the small curvature of the stomach and the initial section of the duodenum. These two peritoneal sheets form the hepatic-gastric ligament (lig.hepatogastricum), located on the left, and the hepatic-duodenum ligament (lig.hepatoduodenale), located on the right. In the thickness of the hepatic-duodenum ligament from the right to the left are common bile duct, portal vein (somewhat behind) and its own hepatic artery, as well as lymph vessels and nodes, nerves. The hepatic-gastric and hepatic-duodenum ligament together constitute a small omentum (omentum minus).

The leaves of the visceral peritoneum of the anterior and posterior walls of the stomach in the region of its large curvature continue to hang down to the level of the upper aperture of the small pelvis (or somewhat higher), and then turn backwards and rise up to the back wall of the stomach (at the level of the pancreas). The four leaves of the visceral peritoneum below the great curvature of the stomach form a large omentum (omentum majus). At the level of the transverse colon all four leaves of the large omentum fuse with the gland ribbon of the anterior wall of the transverse colon. Further, the rear sheets of the large omentum lie on top of the mesentery of the transverse colon, are directed to the posterior abdominal wall and pass into the parietal peritoneum of the posterior wall of the abdominal cavity. Approaching the anterior edge of the pancreas, one leaf of the peritoneum (posterior plate of the large omentum) passes to the anterior surface of the pancreas, the other goes down and passes into the upper sheet of the mesentery of the transverse colon. Part of the large omentum between the large curvature of the stomach and the transverse colon is called the gastric-ligament ligament (lig.gastrocolicum). A large omentum covers the front of the small intestine and parts of the colon. Two sheets of peritoneum, from the large curvature of the stomach to the gates of the spleen, form the gastro-splenic ligament (lig.gastrolienale). Leaves from the cardiac part of the stomach to the diaphragm form a gastro-diaphragmatic ligament (lig.gastrophrenicum). The diaphragmatic splenic ligament (lig.phrenicolienale) is a peritoneal duplication from the diaphragm to the posterior end of the spleen.

In the peritoneal cavity, the upper and lower floors are distinguished, the border between which is the transverse colon and its mesentery. The upper floor of the peritoneal cavity is bounded from above by the diaphragm, along the sides by the lateral walls of the peritoneal (abdominal) cavity, from below - by the transverse colon and its mesentery. The mesentery of the transverse colon passes to the posterior wall of the abdominal cavity at the level of the posterior ends of the X ribs. The stomach, liver, and spleen are located in the upper floor of the peritoneal cavity. At the level of the upper floor are the retroperitoneal lying pancreas, the upper divisions of the duodenum (its initial part - the bulb is located intraperitoneally). In the upper floor of the peritoneal cavity three relatively limited receptacles are distinguished: bags: liver, pre-gastric and omental.

The hepatic bag (bursa hepatica) is located in the right hypochondrium area, the right side of the liver is in it. This bag has a superhepatic cleft (sub-diaphragmatic space) and a subhepatic cleft (subhepatic space). Above, the hepatic bag is bounded by the diaphragm, from below - by the transverse colon and its mesentery, to the left by the crescent ligament of the liver, from behind (in the upper sections) by the coronary ligament. The hepatic bag communicates with the pancreatic bag and the right lateral canal.

The pre-ventricular bag (bursa pregastrica) is located in the frontal plane, anterior to the stomach and small omentum. On the right, the border of this bag is the crescent ligament of the liver, the left border is the diaphragmatic-ligament ligament. The upper wall of the pancreatic bag is formed by the diaphragm, the lower one by the transverse colon, the anterior wall by the anterior wall of the abdomen. On the right, the pre-ventricular bag communicates with the subhepatic slot and the gland bag, to the left - with the left lateral canal.

The gland bag (bursa omentalis) is located behind the stomach, a small omentum and a gastrointestinal ligament. Top of the omentum bag is limited by the tail portion of the liver, from below is the posterior plate of the large omentum, fused with the mesentery of the transverse colon. At the back of the gland bag is limited to the parietal peritoneum, covering the aorta, the lower vena cava, the upper pole of the left kidney, the left adrenal gland, the pancreas. The hollow of the stuffing box is a front slit having three recesses (pockets). The upper glandular recessus (recessus superior omentalis) is located between the lumbar part of the diaphragm behind and the posterior surface of the caudal lobe of the liver in front. The splenic recessus (recessus splenius lienalis) is confined to the front of the gastro-splenic ligament, behind - the diaphragmatic splenic ligament, to the left - by the gates of the spleen. The lower glandular recessus (recessus inferior omentalis) is located between the gastric and ligamentous ligament from the top and from the front and the posterior plate of the large epiploon, which is fused with the mesentery of the transverse colon, from behind. The glandular bag communicates with the hepatic bag (subhepatic slot) by means of a gland opening (foramen epiploicum, s.omentale), or a vinlayer opening. This hole, measuring 3-4 cm, is confined to the front of the hepatic-duodenum ligament, containing a portal vein, hepatic artery and a common hepatic duct. The posterior wall of the opening is formed by the parietal peritoneum covering the lower hollow vein. On top of the gland opening is limited to the caudate lobe of the liver, from the bottom - the upper part of the duodenum.

The lower floor of the peritoneal cavity is under the transverse colon and its mesentery. From below, it is limited by the parietal peritoneum that lines the pelvic floor. In the lower floor of the cavity of the peritoneum two peripheral furrows (two lateral canals) and two mesenteric sinuses are distinguished. The right circumlecate groove (sulcus paracolicus dexter), or the right lateral canal, is located between the right abdominal wall and the ascending colon. The left circumflexal groove (sulcus paracolicus sinister), or the left lateral canal, is bounded by the left abdominal wall and the descending colon. On the back wall of the peritoneal cavity, between the ascending colon on the right and the descending colon on the left, there are two mesenteric sinuses, the boundary between which forms the root of the mesentery of the small intestine. The mesentery root extends from the level of the duodenum-jejunal transition to the left on the posterior wall of the peritoneal cavity to the level of the sacroiliac joint on the right. The right mesenteric sinus (sinus mesentericus dexter) is bounded on the right by the ascending colon, from above by the root of the mesentery of the transverse colon, to the left by the root of the mesentery of the jejunum and ileum. In the right mesenteric sinus, the terminal part of the descending part of the duodenum and its horizontal part, the lower part of the head of the pancreas, part of the inferior vena cava from the root of the mesentery of the small intestine to the duodenum at the top, as well as the right ureter, vessels, nerves, lymph nodes . In the right mesenteric sinus is part of the ileum loops. The left mesenteric sinus (sinus mesentericus sinister) is limited to the left by the descending colon and the mesentery of the sigmoid colon, to the right is the root of the mesentery of the small intestine. At the bottom, this sine is widely communicated with the pelvic cavity. In the left mesenteric sinus, the ascending part of the duodenum is retroperitoneal, the lower half of the left kidney, the terminal section of the abdominal part of the aorta, the left ureter, the vessels, nerves, and lymph nodes; The sinus contains mainly loops of the jejunum.

The parietal peritoneum, lining the posterior wall of the peritoneal cavity, has indentations (pits) - possible places of formation of retroperitoneal hernias. The upper and lower duodenum recesses (recessus duodenales superior et inferior) are located above and under the duodenum-jejunal flexure.

The upper and lower ileo-cecal recesses (recessus ileocaecalis superior et inferior) are located above and below the ilio-cecal transition. Under the dome of the cecum, there is a posterior cecal recess (recessus retrocaecalis). On the left side of the root of the mesentery of the sigmoid colon is the intersigmoid depression (recessus intersygmoideus).

In the cavity of the small pelvis, the peritoneum, passing to its organs, also forms indentations. In men, the peritoneum covers the anterior surface of the upper rectum, then passes to the posterior and then to the upper wall of the bladder and continues into the parietal peritoneum of the anterior abdominal wall. Between the bladder and rectum there is a peritoneal papillary cavity lined with the peritoneum (exavacio recto vesicalis). It is confined to the sides by rectal-vesical folds (plicae recto vesicales), going anteroposterior from the lateral surfaces of the rectum to the bladder. In women, the peritoneum from the anterior surface of the rectum passes to the back wall of the upper part of the vagina, rises upward, covers from behind, and then in front the uterus and fallopian tubes and passes to the bladder. Between the uterus and the bladder there is a vesicle-uterine depression (exavacio vesicoutenna). The deeper rectum-uterine cavity (exavacio rectouterina), or Douglas pocket, is located between the uterus and rectum. It is also lined with the peritoneum and is bounded on the sides by rectum-uterine folds (plicae rectouterinae).

The abdominal covering of the intestine is largely associated with the transformation of the mesentery of the primary intestine. In the first month of embryogenesis, the trunk (below the diaphragm) is suspended to the anterior and posterior walls of the embryo with the help of the ventral and dorsal mesentery - the splanchnopleura derivatives. The ventral mesentery below the umbilical opening disappears early, and the upper part is transformed into a small epiploon and a crescent ligament of the liver. The dorsal mesentery changes its position as a result of increased growth (expansion) of the large curvature of the stomach and turning it down and to the right. As a result of the rotation of the stomach from the sagittal position to the transverse and enhanced growth of its dorsal mesentery, the dorsal mesentery emerges from under the large curvature of the stomach, forming a puffy protrusion (large gland). The back of the dorsal mesentery continues to the back wall of the abdominal cavity, and also gives rise to mesentery of the small and large intestine.

Pair of ectodermal protrusions grow from the anterior wall of the resulting duodenum to the ventral mesentery, the liver and gallbladder. The pancreas is formed from the fusing ventral and dorsal protrusions of the endoderm of the future duodenum, growing into the dorsal mesentery. As a result of turning the stomach and growing the liver, the duodenum and pancreas lose their mobility and acquire a retroperitoneal position.

Age specificities of the peritoneum

Peritoneum in a newborn is thin, transparent. The subperitoneal fatty tissue is poorly developed. Therefore, through the peritoneum the blood vessels and lymph nodes show through.

The small omentum is formed relatively well, the gland opening in the newborn is large. The large omentum at this age is short, thin. It only partially covers the loops of the small intestine. With age, a large omentum lengthens, thickens, a large amount of adipose tissue, lymphoid nodules appears in its thickness. The deepening of the parietal peritoneum, the folds, the pits formed by the peritoneum, are weakly expressed. Their depth increases with age. Often, as the age increases, especially in the elderly, adhesions (spikes) form between the visceral and parietal peritoneal sheets, which affects the functional state of the internal organs.

[1], [2], [3], [4], [5]