Clinical involvement of mesenteric and antimesenteric borders of small bowel loops. I. Normal pattern and relationships.

Anatomic features of the mesentery, as it contributes to the characteristic course and coiled nature of small bowel loops, are analyzed in detail. An understanding of the anatomic definition and relationships of the loops of small intestine permits roentgen identification of their mesenteric and antimesenteric borders. It is established that (a) the concave margin of a small bowel loop, facing toward the axis of the root of the mesentery, is the mesenteric border; and (b) the convex margin of a small bowel loop, facing away from the axis of the root of the mesentery, constitutes the antimesenteric border. The ability to distinguish between the mesenteric and antimesenteric borders of small bowel loops further refines the capabilities of radiologic diagnosis in a variety of intraabdominal disease processes.