Extraperitoneal fascia

Extraperitoneal fascia is a fascial plane – consisting mostly of loose areolar connective tissue – situated between the fascial linings of the walls of the abdominal and pelvic cavities externally, and the parietal peritoneum internally. Its quality and quantity varies considerably. It occupies the extraperitoneal space.

Preperitoneal space

Anteriorly, it forms the thin and fibrous preperitoneal fascia that is interposed between the transversalis fascia, and the parietal peritoneum. The preperitoneal fascia contains a variable amount of fat, loose connective tissue, and membranous tissue. It is provided with its own blood supply. The membranous component lies just deep to the transversalis fascia and has been construed as a second layer of the transversalis fascia by some authors.

Retroperitoneal space

Posteriorly, it forms the thick and fatty pararenal fascia that surrounds the kidneys.