The anatomical extent of the pyloric sphincteric cylinder, the pyloric mucosal zone and the pyloric antrum.

The anatomy of the pyloric sphincteric cylinder is discussed. The pyloric ring is not a separate anatomical structure, but is an inherent party of the cylinder. Contraction of the cylinder narrows the diameter of the pyloric ring, and thus of the pyloric aperture. The extent of the sphincteric cylinder is determined on radiographs. It is seen to be 3-5 cm in length when fully contracted. Anatomical features of the pyloric mucosal zone are reviewed. On the aboral side both the cylinder and the mucosal zone end at the ring. The entire cylinder is lined by pyloric mucosa, but the mucosal zone extends orally beyond the confines of the cylinder. In gastric ulcer it may extend much further up the stomach. In contrast to the cylinder, the greatest length of the mucosal zone is on the lesser curvature. The sphincteric cylinder and the pyloric mucosal zone are clearly defined anatomically. The term 'pyloric antrum', in contrast, has been used in many different senses.