The peritoneum is the serous membrane that lines the abdominal cavity. It includes a parietal and a visceral layer, where the parietal peritoneum which lines the abdominal wall is folded inwards to form the visceral peritoneum that covers the visceral organs. Areas of peritoneal folds form peritoneal reflections that are the basis of several structures in the body, including omenta, mesenteries, gutters and pouches.