The omentum majus is a large, fat-rich fold of the peritoneum that hangs like an apron in front of the abdominal organs and protects them.
Structure and position in the abdomen
The omentum majus is part of the peritoneum, a thin layer of tissue that covers the internal organs in the abdomen. You can think of it as a wide, soft blanket that hangs down from the lower side of the stomach and drapes over the small intestine. It is made up mostly of fatty tissue, with blood vessels, lymph vessels, and connective tissue running through it. In medical language, it is also called the "greater omentum".
What does the omentum majus do?
The omentum majus carries out several important jobs in the abdomen. First, it protects the organs underneath it, such as the small intestine, large intestine, and parts of the stomach, from outside forces, for example when the abdomen receives a knock. The layer of fat acts like a natural cushion.
The omentum majus also plays a role in the immune system. It contains many immune cells that can fight off germs if they enter the abdomen. On top of this, the omentum majus can effectively "seal off" small injuries in the abdomen by moving to the affected area and helping it to heal.
Finally, the fatty tissue it contains acts as an energy store. During times of hunger or illness, the body can draw on these reserves.
When does the omentum majus become medically important?
Usually, the omentum majus is simply a normal part of a healthy abdomen and causes no trouble. In some cases, however, it plays a special role. For example, during certain operations, such as those involving tumours, it can be used as a protective layer or partly removed. During inflammation in the abdomen, such as appendicitis or peritonitis, the omentum majus can also become notable because it moves towards the inflamed area and tries to limit the spread of the inflammation.
Sometimes, metastases can settle in the omentum majus. These are secondary tumours that form as part of certain cancers. In such cases, the omentum majus may be fully or partly removed during an operation to stop the disease from spreading.
The term in medical reports and letters
In medical reports, the term omentum majus often appears in connection with imaging procedures such as ultrasound, CT, or MRI. These reports describe whether the omentum majus looks normal or whether there are any changes, such as thickening, fluid build-up, or deposits. During abdominal operations, it is also commonly noted whether the omentum majus is involved or has changed in any way.
Closing notes
The omentum majus is an important but usually unremarkable part of the abdomen. Its protective and defensive functions are of great importance to the health of the abdominal organs. Only in rare situations, such as with certain illnesses or operations, is it specifically examined or treated. In most cases, the omentum majus is simply a natural part of the body, quietly doing its job in the background.
