Hiatal hernias occur when part of the stomach herniates (pushes through) an opening in the diaphragm. People with GERD may also have a hiatal herniia.
The diaphragm is a large muscle that lies between your abdomen and chest. You use this muscle to help you breathe. Normally, your stomach is below the diaphragm. However, in people with a hiatal hernia, a portion of the stomach pushes up through the muscle. The opening it moves through is called a hiatus.
This condition mostly occurs in people who are over 50 years old. It affects up to 60 percent of people by the time they’re 60, according to the Esophageal Cancer Awareness Association (ECAA).