Sphygmology is the study of pulse and arterial blood pressure. Blood pressure (BP) is the pressure exerted by circulating blood upon the walls of blood vessels. When used without further specification, “blood pressure” usually refers to the arterial pressure in the systemic circulation. It is usually measured at a person’s upper arm. Pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck (carotid artery), on the inside of the elbow (brachial artery), at the wrist (radial artery), at the groin (femoral artery), behind the knee (popliteal artery), near the ankle joint (posterior tibial artery), and on foot (dorsalis pedis artery).