Muscles are composed of cells aligned as elastic fibers, bundled together in a sac of soft tissue known as fascia. They attach at both ends to bones connected by strong, non-elastic tissue commonly called tendons. Because they are elastic, muscles stretch when in use and return to a baseline size when at rest. The motion of a muscle is limited in part by the elasticity and length of the muscle fibers, but also by the length and elasticity of the surrounding fascia. When we move a muscle beyond its capacity, some fibers and even part of the fascial sac tear. These tears do heal but we are left with small, usually microscopic scars. If we repeat a motion often, or maintain a posture for prolonged periods, we alter the shape and flexibility of our muscles. And when doing this, any damage done accumulates and the ratio of scar to healthy tissue increases.
Muscles have areas within them known as motor points. There areas are densey innervated and highly mobile. These motor points sustain the majority of the force of motion and any injury that might result. When a motor point becomes sufficiently scarred, we feel pain and restrictions. This scarred motor point is a trigger point.
A trigger point only exists in the present of damaged tissue and a true trigger point satifies certain criteria; when palpated there is pain at the focal spot but also pain felt in remote referred areas; when palpated the muscle involved will twitch. The pain from trigger points mimics the pain of an irritated nerve although the referred pain zones are distincly different. People often complain of neck pain associated with headaches or back pain associated with leg pain, and often a single trigger point is the sole cause.
