Lead III in the EKG measures from which electrodes?

Lead III in an electrocardiogram (EKG) is derived from the difference in electrical potential between the left arm and the left leg. It specifically measures the voltage between the electrodes placed on these two locations—hence the involvement of the left arm (LA) and left leg (LL).

This lead is significant because it helps in visualizing the heart's electrical activity as it travels from the upper parts of the heart (where the left arm electrode is placed) down towards the lower parts (where the left leg electrode is located). By capturing this information, Lead III contributes to the overall assessment of the heart's rhythm and can be particularly useful in identifying issues related to the inferior region of the heart.

The other options involve combinations of electrodes that do not align with the configuration for Lead III, making the correct identification of electrode pairs essential for accurate heart monitoring.