Scar tissue can form whenever there is an injury. These injuries can arise from an accident, burn, or surgery just to name a few. In the healing process, normal tissue is replaced by denser, fibrous tissue to ensure the continuity of whatever was injured.
However, sometimes in the healing process, the laying down of scar tissue can create pulls on surrounding structures like muscles and ligaments, especially without proper followup through physical therapy. Another one of those structures is the fascia, or connective tissue. Think of your fascia as a sweater but in the form of a onesie, spanning your entire body. Create a knot in the sweater at your ankle (from say, a severely rolled ankle playing basketball) and you might be able to trace the tension it puts on the links of the sweater all the way up to the pelvis, the shoulder, or the head. You may end up having symptoms in any one, or all, of those areas when in fact those symptoms are coming from the pull applied by the formation of scar tissue in your ankle. Working on any of the symptomatic areas alone would not suffice.
The formation of scar tissue also resembles a game of "pick up sticks" (For those not of age, you can google it for images!). Normal, healthy tissue often looks more like those sticks lined up parallel to each other, but scar tissue looks like you threw the sticks on the ground haphazardly, as if starting the game.
Myofascial release and massage do not remove scar tissue but do help to re-align the "sticks" so that the scar tissue becomes more functional and in turn creates less of a pull going outward through the "sweater" of the body. This then makes the body as a whole more functional, increasing range of motion and reducing pain.
It's been said that "no scar should go unevaluated" as any single one "could be just the tip of the iceberg". -John F. Barnes