What is hiatus hernia? Does it Cause Reflux?

This is when the intra-abdominal portion of the oesophagus and the upper stomach “slides” or “slips” up above the diaphragm (flat muscle that separates the chest from the abdomen) into the chest cavity due to widening of the crural hiatus. And in doing so, it compromises the anti-reflux mechanisms by losing the flap valve effect function of the Angle of His and the pinch like effect of the crural muscles. The condition causes the LOS to fail and leads to reflux.