Peritonea

Peritonea are the serous membranes that line the abdominal cavity and envelop the abdominal organs. They consist of the parietal peritoneum, which lines the cavity walls, and the visceral peritoneum, which covers most abdominal organs. The potential space between them is the peritoneal cavity, normally containing a small amount of lubricating serous fluid that reduces friction during movement of the viscera.

Most abdominal organs are intraperitoneal or retroperitoneal. The peritoneum forms folds such as mesenteries, omenta, and ligaments that suspend organs, convey vessels and nerves, and store fat. The mesentery attaches the intestines to the posterior abdominal wall; the greater and lesser omenta connect the stomach and duodenum to other viscera.

Development and distribution: The peritoneum arises from the mesoderm during embryogenesis. Intraperitoneal organs are enclosed by peritoneum, while retroperitoneal organs lie outside the peritoneal cavity; several recesses exist, such as the hepatorenal pouch and the rectouterine or rectovesical pouches.

Functions: The peritoneum produces lubricating fluid, supports movement, provides immune defense through resident macrophages, and partitions the peritoneal cavity to limit the spread of infection. The peritoneal cavity also serves as a conduit for vessels, nerves, and lymphatics via the peritoneal folds.

Clinical relevance: Peritoneal dialysis uses the peritoneal membrane for waste removal in kidney failure. Peritonitis is inflammation of the peritoneum, often due to infection, and can lead to ascites and systemic illness. Peritoneal carcinomatosis refers to metastatic spread of cancer within the peritoneal cavity.