Final answer:
The brachial artery is compressed during a blood pressure measurement using a sphygmomanometer. This procedure involves inflating a cuff to occlude blood flow, then slowly releasing it to obtain systolic and diastolic pressure readings.
Step-by-step explanation:
The artery in the upper limb that is compressed by the sphygmomanometer when taking a blood pressure reading is the brachial artery. During the measurement, a cuff is inflated with air to a pressure above the systolic pressure, which occludes blood flow through the brachial artery. As the pressure in the cuff is slowly reduced, the first sounds of blood spurting through the now partially compressed artery are heard. These sounds correspond to the systolic pressure. The pressure at which the sounds disappear corresponds to the diastolic pressure, indicating that the blood flows freely through the artery.