Myofascial trigger points (MTrPs), also known as trigger points, are described as hyperirritable spots in the skeletal muscle. They are associated with palpable nodules in taut bands of muscle fibers. They are a topic of ongoing controversy, as there is limited data to inform a scientific understanding of the phenomenon. Accordingly, a formal acceptance of myofascial "knots" as an identifiable source of pain is more common among bodyworkers, physical therapists, chiropractors, and osteopathic practitioners. Nonetheless, the concept of trigger points provides a framework which may be used to help address certain musculoskeletal pain.

The trigger point model states that unexplained pain frequently radiates from these points of local tenderness to broader areas, sometimes distant from the trigger point itself. Practitioners claim to have identified reliable referred pain patterns which associate pain in one location with trigger points elsewhere. There is variation in the methodology for diagnosis of trigger points and a dearth of theory to explain how they arise and why they produce specific patterns of referred 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.

Among physicians, various specialists might use trigger point therapy. These include physiatrists (physicians specializing in physical medicine and rehabilitation), family medicine, and orthopedics. Osteopathic as well as chiropractic schools also include trigger points in their training. Other health professionals, such as athletic trainers, occupational therapists, physiotherapists, acupuncturists, massage therapists and structural integrators are also aware of these ideas and many of them make use of trigger points in their clinical work as well.