Lead III primarily records the electrical difference between which two limbs?

Lead III measures the electrical activity of the heart by recording the potential difference between the right arm and the left leg. This lead is one of the standard bipolar leads used in 12-lead electrocardiography (ECG). In this configuration, the electrodes are placed such that Lead III's positive electrode is on the left leg and the negative electrode is on the right arm.

This particular configuration is crucial because it allows clinicians to analyze the heart's electrical activity from multiple angles, providing a comprehensive view of cardiac function. The data obtained from Lead III, combined with other leads, assists in diagnosing various cardiac conditions, such as ischemia or arrhythmias.

Understanding the specific limb leads and their orientations is fundamental for interpreting ECGs accurately and recognizing potential cardiac issues effectively in patient assessments.