[Anatomy of the upper part of the duodenum in men]

The internal anatomy of the first part of the duodenum was studied in 39 anatomical specimens obtained from necropsies. Three mucosal folds were observed in the aboral part of this segment: two folds had a radial disposition and the third a circular one. The localization of these folds corresponded to the narrow zone observed externally in the first part of the duodenum. The functional significance of these results is discussed.