What Is the Peritoneum?

The peritoneum is a membrane made up of two layers. One layer lines the cavity and the other layer lines the organs. The peritoneum helps support the organs in the abdominal cavity and also allows nerves, blood vessels, and lymph vessels to pass through to the organs. The parietal peritoneum lines the abdominal wall and extends to the organs, whereas the visceral peritoneum covers the organs. The peritoneal cavity lies between these two peritoneal layers. It contains a thin layer of fluid that lubricates the peritoneal surfaces.

The visceral peritoneum is served by the same blood, lymphatic vessels, and nerves as the organs it covers. The parietal peritoneum, though, shares circulation and nerve supply with the abdominal wall.

The structures discussed here are formed by the tissues of the peritoneum.

  • The mesentery and the peritoneal folds and ligaments: The mesentery is a double layer of peritoneum with some connective tissue that helps support organs and allows for nerves and blood vessels to travel to those organs. The mesentery anchors the abdominal organs to the posterior abdominal wall, helping keep those organs in place but still allowing for some mobility.

    A peritoneal fold is a part of the peritoneum that is raised from the abdominal wall by the underlying blood vessels and ducts. Each fold forms a pouch-like peritoneal recess. Some peritoneal folds are called peritoneal ligaments when they connect an organ to the abdominal wall or to another organ.

  • The greater and lesser omentums: The omentum is a fatty apron that hangs over the intestines and helps to cushion them. The greater omentum and the lesser omentum are also composed of double layers of peritoneum. The greater omentum is actually four layers thick. They both run between the stomach and the first part of the duodenum to other organs.

    The greater omentum is made up of the following ligaments:

    • Gastrophrenic ligament: This ligament runs from the greater curvature of the stomach to the diaphragm.

    • Gastrosplenic ligament: This ligament runs from the greater curvature of the stomach to the spleen.

    • Gastrocolic ligament: This quite large ligament runs from the greater curvature of the stomach and first part of the duodenum to the transverse colon. It also forms a fatty apron that overlies the intestines.

    The lesser omentum is made up of the following ligaments:

    • Hepatogastric ligament: This ligament runs from the lesser curvature of the stomach to the liver.

    • Hepatoduodenal ligament: This ligament runs from the liver to the duodenum.

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