Let us consider a microscopic view of the muscle in order to understand how it works. Each muscle is composed of thousands of tiny fibers that make up the bulk of the muscle itself.
At various points within a muscle, nerve fibers attach to groups of these tiny muscle fibers. When muscles contract nerve impulses cause groups of muscle fibers to contract or shorten.
When muscles relax, the nerve impulse stops and the groups of muscle fibers relax and lengthen. More information can be found in any modern physiology textbook.
A trigger point is caused by an event that leads to a physiologic malfunction that causes the group of muscle fibers to stay contracted, even when the muscle itself is relaxed. This group of contracted muscle fibers forms a firm nodule which can affect the muscle in the following ways:
- Increased Muscle Tension: The contracted group of muscle fibers prevents the muscle from completely relaxing, increasing muscle stiffness.
- Muscle Weakness: The presence of the contracted fibers prevents the muscle from contracting fully and smoothly.
- Muscle Fatigue: The constantly contracted group of muscle fibers use an incredible amount of energy, causing an “energy crisis” for the rest of the muscle fibers.
- Muscle Spasm: A trigger point can be considered a tiny spasm in a muscle. These spasms can collect more groups of muscle fibers as the pathology progresses. This can lead to a full fledged muscle spasm