Trigger points or trigger sites are described as hyperirritable spots in skeletal muscle that are associated with palpable nodules in taut bands of muscle fibers. Trigger point practitioners believe that palpable nodules are small contraction knots and a common cause of pain. Compression of a trigger point may elicit local tenderness, referred pain, or 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 contracting whereas the local twitch response also refers to the entire muscle but only involves a small twitch, no contraction...