ABSTRACT
Surgical anatomy The two terms abdomen (or abdominal cavity) and peritoneal cavity are not strictly synonymous. The abdomen (or abdominal cavity) refers to the musculoaponeurotic and bony walls that enclose a region lined on the inside by the peritoneum. By contrast, the peritoneal cavity denotes the space enclosed by the peritoneal lining and contains some but not all of the abdominal viscera. The retroperitoneal space lies behind the posterior wall of the peritoneal cavity and contains adipose and areolar ‘packing tissue’ in which lie the retroperitoneal organs. This is continuous with the rest of the extraperitoneal space and is filled with the same packing tissue separating the musculoaponeurotic anterolateral walls from the peritoneal membrane. Underneath the packing tissue is a fascial layer (endoabdominal fascia) that covers the muscles of the back and this is continuous with the transversalis fascia anterolateral on both sides.
