The retroperitoneum is the part of the abdominal cavity that lies between the posterior parietal peritoneum anteriorly and the posterior abdominal wall 4. It is C-shaped on axial cross-sections with a convexity projecting anteriorly in the midline. Gross anatomy The retroperitoneum is variably defined, mostly by the lack of consensus definition for the posterior abdominal and whether the psoas muscles and quadratus lumborum are boundaries or contents 4. It can have up to five compartments depend

Retroperitoneal organs: definition, structures (preview) - Human Anatomy | Kenhub

Retroperitoneal space and Retroperitoneal organs