Hiatus hernia (also called hiatal hernia) is a disorder affecting the gastroesophageal junction, the site where the esophagus (food tube) joins the stomach.
See the picture on the left. The esophagus is a tube, measuring about 10 inches long, that starts at the lower end of the pharynx (throat) and extends down through the chest and into the abdomen through an opening in the diaphragm. The diaphragm is a sheet-like muscle that separates the chest cavity from the abdominal cavity and is one of the main muscles that allows us to breathe. The opening in the diaphragm through which the esophagus passes is called the hiatus. At its lower end the esophagus joins the stomach. The stomach is a bag-like structure where some digestion of food occurs. The stomach contains very strong acid (hydrochloric acid) that performs two functions - the acid kills most bacteria (but not all) and activates a digestive enzyme. The stomach is usually resistant to this acid and is not harmed.
Notice in the picture how the esophagus joins the stomach at an angle. This angle helps to prevent the acid in the stomach from flowing into the esophagus. In hiatus hernia, the stomach pushes its way through the hiatus into the chest (click here for animation). In another, less common type of hiatus hernia, the rounded top part of the stomach pushes up beside the lower part of the esophagus. The causes of hiatus hernia may include poor muscle tone around the hiatus, increased fat pushing open the hiatus, and increased pressure in the abdomen pushing the stomach upwards through the hiatus. The herniation of the stomach through the hiatus causes loss of the normal angle between the esophagus and stomach and allows acid to reflux into the esophagus. The esophagus is not resistant to acid and becomes inflammed. This produces heartburn and may also lead to other complications.
Note: The material provided in this web page is educational in nature and not medical advice. It is meant neither for self-diagnosis nor as a treatment recommendation. If you are concerned about any condition you think you may have, CONSULT YOUR DOCTOR.