Physical Therapy Aide Training Practice Test

Montage describes how the electrodes are arranged to derive a signal. A quadripolar montage uses four electrodes placed in a cross pattern around the area of interest. With four contact points, you can form two differential measurements across perpendicular axes and compare them, which helps localize activity more precisely and reduces common noise that affects all electrodes similarly. This setup offers more spatial information than a simple two-electrode arrangement, which provides only a single differential measurement and less ability to pinpoint sources or reject interference. In contrast, a two-electrode (bipolar) setup uses just a pair of electrodes to measure one difference, offering limited localization. A monopolar arrangement uses one active electrode with a distant reference, still essentially a single differential depending on how many references are used. A tripolar arrangement uses three electrodes to create two differentials with a shared reference, but it still involves fewer electrodes and a different configuration than the four-electrode quadripolar cross layout.