Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Radiation of pains denotes the characteristic of some types of pains to spread out to distant parts than the origin of the pain. For example, in angina pectoris, apart from pains in the epigastrium, back, neck, jaw, or shoulders, radiation of pain can also be felt in arms (often inner left arm), shoulders, and neck into the jaw. It is well useful in doing medical stuff. Angina pectoris, commonly known as angina, is severe chest pain due to ischemia (a lack of blood and hence oxygen supply) of the heart muscle, generally due to obstruction or spasm of the coronary arteries (the heart''s blood vessels). Coronary artery disease, the main cause of angina, is due to atherosclerosis of the cardiac arteries. The term derives from the Latin angina ("infection of the throat") from the Greek ankhone ("strangling"), and the Latin pectus ("chest"), and can therefore be translated as "a strangling feeling in the chest".