The peritoneum is the serous membrane that forms the lining of the abdominal cavity. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum supports the abdominal organs and serves as a conduit for their blood vessels, lymph vessels and nerves. The outer layer, called the parietal peritoneum, is attached to the abdominal wall and the pelvic walls