"Sphincter" of the minor papilla of the human duodenum.

The arrangement of the smooth muscle and elastic and collagen fibers of the minor papilla of the human duodenum was studied on 53 duodenopancreatic specimens obtained from adults of both sexes. Methods included stereological analyses of gross anatomical specimens and thick and thin microscopic sections. The muscular and elastic fibers of the minor papilla have a unidirectional arrangement by which the contraction of its smooth muscular fibers causes opening of its orifice allowing the flow of the pancreatic juice into the duodenum. It is not a typical anatomical sphincter.