Hiatus hernia

This is of two types. Sliding (commoner) and rolling. The main factor in its occurrence is weakness of the sub-diaphragmatic layer of fascia. Note the level of the diaphragm and see that the stomach has slid through the diaphragm, from the abdomen, into the thorax. With it , it pulls along the sub diaphragmatic layer.  It leads to symptoms of GERD. 

In this X-ray, a sliding hernia is shown. If there were a ROLLING hernia on the other hand, it would lead to symptoms like Angina.