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In human anatomy, the esophageal hiatus is an opening in the diaphragm that provides passage for the esophagus as well as several key veins and arteries. It is one of three natural passageways through the diaphragm, a thin muscle that sits in the upper chest cavity. The main role of the diaphragm is to assist the lungs in breathing, but its location makes it a necessary passageway from the throat and mouth downward. In most healthy people, the hiatus never causes problems and isn’t often though about outside of formal anatomy studies. Issues can arise pretty quickly if the passageway becomes enlarged, however, as this can cause dislodgement of the esophagus, which itself can lead to a variety of throat and digestive problems. Hernias are also somewhat common, and happen when part of the stomach lining bulges up through the hiatus opening. Sometimes these can be treated with medications and lifestyle modifications, but they may also require surgery to correct.
The diaphragm, technically called the thoracic diaphragm, is a thin muscle that stretches across the chest at the bottom of the ribs, just below the lungs. It has several openings; in addition to the hole for the esophagus, it also features the aortic hiatus and the caval opening, through which pass the artery and vein that carry blood between the heart and lungs. The esophageal hiatus is located near the center of the diaphragm, in the area known as the right crus. In addition to the esophagus, other structures that pass through the diaphragm at this location include the vagus nerve and several blood vessels.
More than anything else, the esophageal hiatus is a passageway, and the esophagus, which is the food pipe to the stomach, is the primary beneficiary. As the esophagus passes through the hiatus on its way to the stomach, it is constricted by muscles to keep stomach fluids from escaping into the esophagus or lungs when a person breathes. A firm gasp and a bit of tension in the muscle keep everything in place.
Problems usually arise pretty quickly if the opening becomes enlarged or otherwise stretched. If the esophagus isn’t held firmly, it can begin to vibrate; it can also grow distended, which can cause swelling and inflammation. In extreme cases other particulates can flow up and out of the hole, or can become lodged in it. Sometimes certain diets and medications can encourage the muscular fibers to constrict, but more often enlargements require surgical correction.
Hernias, which are areas where portions of the stomach become enlarged and bulge through the opening, can also be quite serious. Although some hiatal hernias are simply inherited genetically, most develop over several years, and tend to be most common in people over age 50. Some present symptoms such as severe heartburn or gastrointestinal reflux disease (GERD), chest infections due to stomach fluids being breathed into bronchials or lungs, and vomiting; other hernias have no symptoms. If symptoms become severe, or if a person suffers severe chest pain or is unable to have bowel movements or pass gas, medical attention must be sought immediately. This could mean there is an obstruction, or the hernia has become strangulated.
When an esophageal hiatus becomes herniated, there are two main types of rupture. The sliding hiatal hernias make up over 90% of cases, and happen when part of the stomach and the junction of the esophagus slide up through the hiatus opening while swallowing. At the end of the swallow, the stomach slides back through the hiatus into normal position in the abdomen. A paraesophageal hernia is when the esophageal junction remains in place. In these cases, part of the stomach bulges up past it to sit beside the esophagus in the chest area permanently. A paraesophageal hernia is dangerous as it can become strangulated and constrict blood flow, and typically requires surgery.