I think one of the features of the diaphragm muscle that is often overlooked is that the strong tendons that moor it down to the lumbar spine (called the crura) have what appear to be a grip around the main blood vessel to the lower part of the body, the aorta. Tighten and constrict the diaphragm (a common enough condition and probably one of the ways we get a grip on our emotions) and we squeeze and grip the aorta too. I wouldn’t be surprised if this is a feature to high blood pressure and a way to maintain pressure in our head. Release the diaphragm(all the way down into the cura) and we take a lot of pressure off our circulatory system and drop a lot of the heat, pressure, and congestion in our head. Here are two diagrams and views of the diaphragm from below. See how the crura wrap around the aorta. If the crura tighten sufficiently, they apply a scissor grip to the aorta.
