Overview
This lecture covers the anatomy of the retroperitoneum, identification of its organs, and its division into three main spaces with related fascia and anatomical relationships.
Retroperitoneal Organs and Identification
- The retroperitoneum lies posterior to the peritoneal cavity, separated by the parietal peritoneum.
- Key retroperitoneal organs: adrenal glands, kidneys, proximal ureters, pancreas (except tail), aorta, inferior vena cava, ascending and descending colon, and parts of the duodenum (D2, D3, D4).
- Adrenal glands are located superior and slightly anterior to the kidneys.
- The pancreas' head and body are retroperitoneal; the tail is intraperitoneal.
- Ascending and descending colon, and duodenal segments D2, D3, D4, are retroperitoneal.
Division of the Retroperitoneum into Spaces
- Retroperitoneum is divided into three spaces using fascial planes: anterior pararenal, perirenal, and posterior pararenal spaces.
- Anterior Pararenal Space: Contains pancreas (except tail), duodenum (D2–D4), ascending/descending colon; bounded anteriorly by parietal peritoneum and posteriorly by anterior renal fascia (Gerota's fascia).
- Perirenal Space: Contains kidneys, adrenal glands, proximal ureters, renal vessels; bounded by anterior renal fascia (Gerota's) and posterior renal fascia (Zuckerkandl's).
- Posterior Pararenal Space: Primarily contains fat; bounded anteriorly by posterior renal fascia and posteriorly by transversalis fascia.
Fascia and Anatomical Boundaries
- Gerota's Fascia (anterior renal fascia) and Zuckerkandl's Fascia (posterior renal fascia) are key boundaries of perirenal space.
- Lateral conal fascia forms the lateral boundary where Gerota's and Zuckerkandl's fascia fuse.
- Posterior pararenal space is posterior to Zuckerkandl's fascia and anterior to transversalis fascia.
Imaging and Clinical Relevance
- CT scans and X-rays help visualize these spaces and their contents, especially with disease (e.g., retroperitoneal fibrosis).
- Pathologies often remain confined to specific retroperitoneal spaces.
Key Terms & Definitions
- Retroperitoneum — the anatomical space behind the peritoneal cavity.
- Peritoneum — membrane lining the abdominal cavity (parietal) and covering abdominal organs (visceral).
- Gerota's Fascia — anterior renal fascia surrounding the kidney.
- Zuckerkandl's Fascia — posterior renal fascia.
- Perirenal Space — compartment containing the kidney and adrenal gland, between Gerota's and Zuckerkandl's fascia.
- Anterior Pararenal Space — compartment between the peritoneum and Gerota's fascia, containing GI structures.
- Posterior Pararenal Space — space behind Zuckerkandl's fascia, filled with fat.
- Transversalis Fascia — fascia forming the posterior boundary of the posterior pararenal space.
Action Items / Next Steps
- Review peritoneal cavity notes from last week for context.
- Practice identifying retroperitoneal organs and spaces on sample CT images.
- Memorize key fascial boundaries and contents of each retroperitoneal space.