Basic to an understanding of the clinical and radiologic criteria is precise knowledge of the anatomy of the extraperitoneal fascial planes, compartments, and relationships. The retroperitoneal space is bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. It extends from the pelvic brim inferiorly to the diaphragm superiorly. The major organs and structures within it include (a) the adrenal glands, kidneys, and ureters; (b) the descending, transverse, and ascending portions of the duodenum, and the pancreas; (c) the great vessels and branches; and (d) the ascending and descending colon.
The intraperitoneal structures do not simply occupy the anterior half of the abdomen and the extraperitoneal structures the posterior half. Rather, the extraperitoneal space is mildly C-shaped, with its convexity projecting anteriorly in the midline. This is a function of both the particular relationships of the abdominal organs and their accommodation to the lordotic curvature of the lumbar spine. In this way, segments of the extraperitoneal region (e.g., the body of the pancreas and the duodenal loop) lie considerably anterior to portions of in-traperitoneal viscera (e.g., the spleen and posterior aspects of the liver).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.