The spiral constrictor of the gastroesophageal junction.

The gastroesophageal region was reconstructed from the histological analyses of five human newborn infants. In addition, the nusculature of eight (3 newborn and 5 adult) human stomachs obtained from autopsies, with the lower one-third of the esophagus attached, was dissected with the aid of a binocular dissecting microscope. The muscularis mucosae, in the region of the gastroesophageal junction, exhibited no increase in thickness, nor was there any indication of special mucosal folds. In addition, the gastroesophageal junction contained no morphologic evidence that would support the existence of an anatomic sphincter (a localized thickening of circular muscle fibers). However, the obliquely arranged inner circular muscle fibers of the esophagus separated into fascicular bundles below the esophageal opening. Some of the fasciculi, as they descended, again became circular in shape and continued into the stomach, forming the middle circular muscle layer, while other fasciculi maintained their oblique course toward the left surface of the esophagus. These fasciculi, coursing on the anterior and posterior surfaces of the esophagus, crossed and interdigitated along the left surface of the esophagus in the region of the incisura cardiaca. After crossing, the oblique fasciculi descended into the stomach forming the inner oblique muscle layer. Based upon this description of crossing and interdigitating fasciculi, it is suggested that closure of the gastroesophageal junction may be due to contraction of spirally arranged muscle. Since the term "sphincter" generally implies a circular structure, it is proposed that the term "spiral constrictor" be considered in naming this anatomical arrangement.