Figure 1From: Myofascial trigger points: spontaneous electrical activity and its consequences for pain induction and propagationAn example of motor behavior of spontaneous electrical activity (SEA) of a myofascial trigger point (MTP) during trapezius muscle contraction. The electromyographic (EMG) activity of the SEA of an MTP is similar to the surface EMG over an MTP on one side of the upper trapezius and to both the surface and intramuscular EMG activity of a normal muscle point on the other side of the upper trapezius. Note: following needle insertion into a MTP, surface EMG recording shows low amplitude activities.Back to article page