Trigger points are described as irritable spots in skeletal muscle that are associated with palpable nodules in taut bands of muscle fibers. They are believed to be small contraction knots and a common cause of pain. Compression of a trigger point may elicit local tenderness, referred pain, or a local twitch response. The local twitch response is not the same as a muscle spasm. This is because a muscle spasm refers to the entire muscle entirely contracting whereas the local twitch response also refers to the entire muscle but only involves a small twitch - no contraction. Unexplained pain frequently radiates from these points of local tenderness to broader areas, sometimes distant from the trigger point itself.  Trigger points can maintain constant pain patterns until treated with either ischemic compression (pressing the trigger point) or stretching.