Trigger points are severely painful areas of muscle. When in use, muscles normally contract and relax. However, when the muscles are unable to relax, a trigger point—a tight knot or band of muscle—may develop.
Myofascial pain is the term used to describe chronic muscle pain and areas of trigger points. This pain often disseminates throughout the affected muscle. Myofascial pain syndrome occurs when muscle pain does not resolve on its own, and is commonly associated with fibromyalgia.