ENThe retroperitoneal space (retroperitoneum) is the anatomical space (sometimes a potential space) in the abdominal cavity behind (retro) the peritoneum.
ENThe peritoneum /ˌpɛrᵻtəˈniːəm/ is the serous membrane that forms the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as ann...