Embolism is the blockage of foreign objects in the blood vessels, affecting blood flow. Foreign objects are called emboli. Common emboli include atherosclerotic plaques formed in blood vessel walls, thrombus from heart fibrillation, gas, fat, etc. If there are blood clots in important blood vessels, it will seriously affect the body's function. For example, a thrombus form in coronary atherosclerosis can cause myocardial infarction ,which is life-threatening. Head thrombosis can cause a variety of physical abnormalities.