Greater omentum

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Illustration from Sobotta's Human Anatomy
The greater omentum ( English Greater omentum ), on a lithograph from the book Gray's Anatomy .

The greater omentum , German large network , in humans and other mammals, a peritoneum ( peritoneum ) coated in fat and rich in connective tissue structure of the greater curvature of the stomach of the and the transverse part of the colon ( transverse colon ) hanging apron-like and the small intestine usually completely covered. In the case of slaughtered cattle, one speaks of fat net .

The greater omentum is responsible for the immune defense in the abdomen. It contains a large number of macrophages and lymphocytes which, in the event of inflammation, increasingly lie on the affected areas and thus protect against peritonitis . It also plays a role both in fat storage and in the regulation of fluid balance in the peritoneal space .

Development history

In evolutionary terms , the greater omentum is formed from a portion of the back-side Magengekröses ( mesogastrium dorsal ): Due to the 90 ° rotation of the stomach around the longitudinal axis - the rear wall of the stomach, which grows faster in this rotation is in this case as a large curvature ( greater curvature ) of shifted to the left - the back mesentery is also initially pulled to the left, so it has to grow. Since this part of the dorsal mesentery grows more than would be necessary for the mere rotational movement of the stomach, a duplication or, in relation to the peritoneal lining, a four-leaf structure is created, the inner peritoneum leaves soon merging with one another. With the rotation of the stomach around a sagittal axis (its transverse displacement), the greater omentum assumes its position above the transverse colon (transverse intestine) and now hangs down to the level of the navel. The serosal coatings of the greater omentum and transverse colon also merge at their contact surfaces.

Omental bursa

In humans, crevices appear in the dorsal mesentery in the 3rd embryonic month, which fuse together. They form the recessus pneumato-entericus dexter (there is also a left recess, which, however, quickly regresses), which initially connects the chest and abdominal cavity. This passage is closed upwards by the resulting diaphragm . With the rotation of the stomach around the longitudinal axis and the movement of the dorsal mesentery on its right side, the omental bursa is created as a pocket open to the right, which ultimately comes to lie behind the stomach. It serves as a shifting layer for this and contributes to its undisturbed mobility. After completion of physical development, it is the largest peritoneum niche in the abdominal cavity.

It is bounded to the rear by the parietal peritoneum, which covers the pancreas and hunched forward with the omentale tuberosity into the bursa, and the parietal peritoneum of the posterior abdominal wall, and to the front by the lesser omentum , stomach and gastrocolic ligament , the connecting piece between stomach and transverse intestine, which arose from the anterior portion of the dorsal mesogastrium . Bulges ( recessus ) arise upwards as a superior recess , which runs between the inferior vena cava and esophagus under the liver , and downwards as an inferior recess between the stomach and the transverse intestine. In newborns this often continues between the two as yet unfused leaves of the greater omentum. It is connected to the free abdominal cavity via the vestibulum bursae (the atrium of the pocket) and the omentale foramen ( foramen Winslowi or foramen epiploicum ).

The omental bursa is therefore of great relevance for abdominal surgery , since it is the only way to access the pancreas and the adjacent areas. The only natural access route is the omental foramen. Surgically, ventral routes can be created via the lesser omentum and the gastrocolic ligament , caudally through the mesentery of the transverse colon .

Pig net

The omentum majus from pork, in the kitchen language fat net or just called net , is used in the kitchen to wrap various meat dishes, for example for the Swiss Adrio or in general for the roll roast or meat loaf .

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  1. See also Johannes Steudel : The anatomical term "network". In: Sudhoff's archive. Volume 47, 1963. pp. 383-386.