LO10 - Abdominal Wall

10. Understand which abdominal structures are intraperitoneal, primarily retroperitoneal, and secondarily retroperitoneal.

    • Intraperitoneal refers to viscera covered by visceral peritoneum and suspended within, but not inside the peritoneal cavity.
    • Retroperitoneal refers to organs located posterior to the peritoneum. Structures may either be primary or secondary retroperitoneal, depending on their developmental history. The anterior surfaces of these structures are typically covered with parieral peritoneum.
    • A primary retroperitoneal structure develops and remains retroperitoneal.
    • Secondary retroperitoneal structures begin development intraperitoneal, but eventually are drawn retroperitoneal.
    • Fusion fascia are double layers of connective tissue formed by secondarily retroperitoneal structures colliding with the posterior body wall. Fusion fascia consist of what was previously parietal peritoneum and the visceral peritoneum on the posterior aspect of a structure fusing. The visceral peritoneum of the anterior structure then becomes the parietal peritoneum. Fusion fascia are clinically important because they allow for greater facility in either mobilizing or accessing a structure and are devoid of neurovasculature.

How structures become secondarily retroperitoneal: