Final answer:
The final Korotkoff sound occurs when cuff pressure equals diastolic pressure, indicating that blood flow has resumed normally through the artery.
Step-by-step explanation:
The final Korotkoff sound is heard when cuff pressure is equal to diastolic pressure. During blood pressure measurement using a sphygmomanometer and a stethoscope, when the pressure in the cuff is reduced to below the systolic blood pressure, blood begins to flow through the brachial artery in the arm, creating the Korotkoff sounds. The first sound corresponds to the systolic pressure, and the point at which the last Korotkoff sound can be heard, which signifies the resumption of continuous blood flow, corresponds to the diastolic pressure.