Myofascial pain syndrome is characterized by on-going muscle pain and tenderness. It can affect various muscles and fasciae of the body. Trigger points develop in myofascial pain syndrome, which are small areas of tight, painful muscle tissue. Their size varies from a peanut to a pea.
Sometimes trigger points can be felt under the skin. Pressing on the trigger point is painful, but pain may occur not only on the spot, but also in a different part of the body. This is called referred pain. This might make the diagnosis of myofascial pain difficult. Fortunately, typical patterns of referred pain are well known and documented for many trigger points.