Triggerpoint is a painful muscle-knot which is closely related to the muscle fibers. Since the blood-flow and the metabolism of the muscle is inadequate at this point, the optimal functions of the muscle get damaged which all lead to the stiffness of the muscle. You do not have to worry about the existence of the triggerpoints, it is a natural process. This is how our muscles react to stress (physical, emotional). In the body there can be triggerpoints in all the muscles which can cause typical radiation and painful symptoms.