Pain is the most common symptom and perhaps the most important one. It is important to distinguish between acute and prolonged pain.
Acute pain has a physiological purpose.
It is a warning sign of injury, such as a sprained ligament. During the first days after an injury, the pain tells the body to avoid movement which would prevent healing. This is why the neck becomes stiff a short time after the injury. However, muscles sometimes seem to react negatively to pain, even if they were not injured from the beginning. If muscles are in hypertension long enough, the function of the muscular tissue can be disturbed.