The peritoneum is a think serous membrane that lines the deep surface of the abdomino-pelvic cavity and the organs contained in it. The organs located inside of the peritoneum are called "intraperitoneal" and the others are called " retroperitoneal" (often lying behind the peritoneum). Some organs are partly inside and partly outside of the peritoneum (pancreas).
The two peritoneal sheets can move independently of each other.
The peritoneum was a membrane which surrounds many organs. 1: diaphragm - 2 : liver - 3 : stomach - 4 : bladder- 5 : pubic bone - 6 : vagina - 7 : pancreas - 8 : duodenum - 9 : transverse colon - 10 : small intestine - 11 : uterus - 12 : rectum. © Wikimedia Commons