Korotkoff sounds are blood flow sounds that healthcare providers observe while taking blood pressure with a sphygmomanometer over the brachial artery in the antecubital fossa. These Korotkoff sounds appear and disappear as the blood pressure cuff is inflated and deflated.
As the heart contracts, blood is forced through the arteries causing a rise in pressure, called systolic pressure. This is followed by a decrease in pressure as the heart prepares for another beat. This low pressure is called the diastolic pressure.