Anatomy and Function
The omentum majus means translated “big net” and describes a duplication of the peritoneum. It is attached to the underside of the stomach (large curvature) as well as to the horizontally running part of the colon (transverse colon) and hangs down in the shape of an apron. Thus it covers the deep abdominal organs as well as the entire small intestine and the transverse colon.
Historically, the omentum majus was formed by the rotation of the stomach. It was formed from the rear connection of the stomach system to the back wall of the body cavity and was strongly elongated by the rotation and tilting of the stomach during embryonic development. The size and superficial position of the omentum majus protects the organs underneath.
It thus serves primarily as a cushion. In addition, the omentum majus consists of fatty tissue and contains lymph nodes that serve the immune system. These usually settle secondarily in the omentum majus.
Since this structure is very mobile and shiftable, it is easy for the omentum majus to become sticky or to grow together with the peritoneum of neighboring organs. This is particularly favored by local inflammation. The movement of the organs is restricted.
The resulting connections between the organs and the omentum majus are called bridges. They can become very dangerous if they lead to entrapment of the organs below. For example, a bridge can be an obstacle to the passage of the bowel and lead to blockages or even ileus.
On the other hand, the omentum majus can contribute to the containment of an inflammation due to its large number of immune defense cells and its ability to cover an organ. The spread and thus the danger of life-threatening peritonitis (inflammation of the peritoneum) is reduced. In addition, the omentum majus plays a major role in the fluid regulation of the peritoneal cavity, as it can absorb and release a large amount of fluid via its large surface area.
Finally, the omentum majus also has an important function as the body’s fat store. It can serve as an energy reserve in times of reduced food intake. In overweight people, the omentum majus is often enlarged and several centimeters thick. This also makes it an obstacle in abdominal surgery. Often it ends up in a different position than it originally was.
