If you are suffering from any of the following, you may have referred pain from the upper trapezius trigger points:
Headaches on the temples or tension headaches, facial, temple, or jaw pain, pain behind the eye, dizziness or vertigo (in conjunction with the sternocleidomastoid muscle), severe neck pain, a stiff neck, or limited range-of-motion and intolerance to weight on your shoulders.
What referred pain means is, that even though the origin of the pain is for example at the top of your shoulders, about midway between the neck and the shoulder joint, the pain is experienced elsewhere, such as the head, eyes, or jaw.

There are 200 paired muscles (skeletal muscle) that’s a total of 400 muscles, any one of which can develop trigger points.
Trigger points develop as a result of muscular injuries, strains, and trauma. This causes knotted fibers which restrict the fresh blood supply needed by the muscle cells. In addition, there is often a shortening of the muscle fiber to protect itself from further injury. Trigger points can also develop as a result of structural imbalances, improper body posture, poor nutrition and stress. Over time the muscle learns to avoid pain by limiting its movement. This results in a loss of range of motion of the joint and the probability that the muscle and associated structures will develop trigger points. When treating trigger points there is often a sense of release accompanied.

Image: levator scapulae.
Levator scapulae trigger points causes Neck pain, which may extend to the head causing a headache, pain and restricted range of movement, deep, achy pain and tightness on the upper back along the top of the shoulder blade or neck.
Treating Trigger Points:
Acupuncture is a treatment that involves a very thin needle being pushed through the skin to stimulate for example a trigger point. Acupuncture may release the tight muscle bands associated with trigger points and lead to decreased pain and improved function.
Electroacupuncture uses the same principles as acupuncture, and the same trigger points as the traditional needling method, but it adds a microcurrent to the needle.

Image: Quadratus Lumborum Trigger points and referral pain pattern
Athletes might also see some promising results from electroacupuncture. Electroacupuncture can help with optimal performance and recovery from training sessions thanks to how effectively it releases trigger points.
With a trigger point technique, you can get the muscle to twitch and then relax. The outcome is a more balanced muscle structure and pain or tightness relief in that particular area. This pay-off usually occurs after one to three sessions.
