Debatable points in the anatomy of the lower oesophagus.

Abstract

Anatomical findings in 132 post-mortem specimens of esophagus, stomach, and diaphragm are discussed. Seven cases of hiatal hernia occurred one of which had most of the esophagus lined by columnar epithelium. The transverse muscle layer of the muscularis propria is a reticular layer and contributes muscle bundles to the longitudinal layer. Both muscle layers contract together, simultaneously shortening and narrowing the contracted segment and causing the mucosa to form large longitudinal folds. In the notch between the left lateral aspects of the lower end of the esophagus and the fundus of the stomach lie the sling fibres of the stomach. Displacement of these fibres above the hiatus enables a diagnosis of hiatal hernia to be made post mortem and on Ba studies in living persons. In just over half the cases there was no evidence of muscular contraction in the esophagus, and the tubular esophagus expanded in a fusiform manner at its lower end before entering the stomach at the level of the sling fibres. A localized area of contraction at the upper limit of the vestibule (the inferior esophageal sphincter) was present in about 1/3. The inferior esophageal spinchter and the whole vestibule were contracted in the remaining cases. Each of these appearances is merely a phase of the normal action seen in the distal end of the esophagus during swallowing. The variability of the mucosal junction is confirmed. Longitudinal folds form in the esophagus when the muscles contract because the mucosa is attached to the muscle wall at fixed points in its circumference. These folds play an important part in the closure of the esophageal lumen. A transverse mucosal fold forms at the same level as the sling fibres of the stomach when the vestibule is relaxed and distended. This fold is not related to the mucosal junction. The esophagus is anchored to the hiatus by the phreno-esophageal membrane, which permits the esophagus to slide up and down in the hiatus and prevents the stomach from herniating into the chest. Like the mucosal junction, the membrane has irregular digitations and thus does not define the limits of the vestibule or form either the inferior esophageal sphincter or the mucosal fold at the level of the sling fibres of the stomach. In cases of sliding hiatal hernia the phreno-esophageal membrane is attenuated.