Myofascial pain syndromes caused by trigger points (TrPs) in muscle are a common cause of local and generalized pain. Trigger points are hyperirritable zones in contracted bands of muscle, thought to be caused by muscle overload or stress. Stress TrPs have characteristic electromyographic features, and can be visualized with ultrasound and magnetic resonance elastography. Trigger point needling or injection can be effective in inactivating TrP, but correcting triggers is also critical.