The typical location of angina pectoris is the precordial region, usually between the 4th ribs on the left midclavicular line, in an area the size of the palm of your hand. In addition to the precordial region, the retrosternal or lower middle sternum is also a good location for angina pectoris. In addition to the typical pain in the precordial region, patients with angina can also have radiating pain that can radiate to the left arm, shoulder, back, neck, upper abdomen, jaw, and gums, often referred to clinically as radicular pain. Patients with angina pectoris develop radiating pain because angina pectoris is a visceral neuropathic pain of the heart. This visceral neuropathic pain is insensitive and not very accurately localized on the body surface, not always effectively localized in the precordial region, and it is possible that peripheral nerves in other areas sense the pain and develop the corresponding pain. The most typical nature of angina is a crushing, tightening sensation, but dullness may also be present. Usually angina attacks last from a few minutes to 10 minutes and usually do not exceed 20 minutes. If the pain is prolonged, one should be alert for the development of a myocardial infarction. If a patient experiences angina, he or she should remain quiet, rest, and take quick treatment with nitroglycerin, in which case the chest pain may be relieved within a few minutes. The vast majority of patients with angina will have exertion-related triggers, and patients often experience chest pain during exercise, emotional stress, a full meal, constipation, or overexertion. A small number of patients have no trigger for angina and may have episodes at rest, which are classified as unstable angina.