Which organs are classified as retroperitoneal?

Retroperitoneal organs are those that are located behind the peritoneum, the membrane that lines the abdominal cavity. The kidneys and pancreas are indeed classified as retroperitoneal organs. The kidneys are positioned behind the peritoneum on either side of the spine, allowing them to maintain their position and function without being fully surrounded by the peritoneal cavity. The pancreas also lies retroperitoneally, with its head nestled in the curve of the duodenum and the rest of the gland extending towards the left side of the body, near the spleen.

In contrast, the liver and spleen are intraperitoneal organs, meaning they are completely surrounded by peritoneum, as are the stomach and intestines, which are also classified as intraperitoneal due to their enclosed relationship within the abdominal cavity. The gallbladder is similarly considered intraperitoneal, located underneath the liver, and while the bladder is situated in the pelvic cavity, it is not classified as retroperitoneal. Thus, the distinction between retroperitoneal and other abdominal organs helps in understanding their anatomical relationships and clinical significance.