First, a little anatomy. The diaphragm (muscle-tendon septum) separates the chest cavity from the abdominal cavity. Through the esophageal opening of the diaphragm, the esophagus descends into the abdominal cavity and passes into the stomach and that part of it, which is called the cardiac.
At the junction of the esophagus into the stomach, the muscle fibers form a sphincter (pulp). Normally, outside of swallowing, this sphincter is closed, which prevents the contents of the stomach and gastric juice from entering the esophagus. Continue reading