The peritoneum is a complex, serous membrane lining the lower abdominal cavity. Its function is to provide a lubricating surface against which the viscera may move so that they are not damaged by friction. In the male body, the peritoneum is predominately a closed, sac-like structure, while in the female, the fallopian tubes penetrate the peritoneum. The peritoneum contains the lesser cavity at the upper abdomen, near the stomach and transverse colon. The duplicating folds of the peritoneum are called omenta. The greater omentum is the largest of these and hangs down from the stomach over the small intestine. The greater omentum is composed of highly vascularized and innervated fatty tissue, protecting the lower viscera from shock and infection. Research Peritoneum