The diaphragm is a dome shaped muscular partition between the thorax and the abdomen in mammals.  It has a functional role in breathing.  Like all muscles the diaphragm requires a supply of oxygenated blood.  The arteries that supply the diaphragm with oxygen are the phrenic arteries.  There are superior and inferior phrenic arteries. The superior supplies the superior aspect of the diaphragm and the inferior supply the abdominal aspect of the diaphragm. I know anatomy is a huge subject and there seems to be a lot of memorization but here’s a handy tip for remembering the phrenic arteries and the diaphragm. They both have “ph” in them creating the “fa” sound.  You don’t see “ph” too often in anatomical structures.  Phrenic arteries and diaphragm are two of them.