Trigger points are hyper irritable knots found in muscle tissue. These points form in a muscle due to overload stress. Trigger points can form anywhere, in any muscle. Once formed they irritate sensory nerves and produce pain, refered pain, weakness, and stiffness. Trigger points will also mimic symptoms of other conditions such as “sciatica” or Carple tunnel syndrome. Trigger points will not go away on there own, they must be manually released with hands on techniques like trigger point massage.
Trigger points form only in muscles. They form as a local contraction in a small number of muscle fibers in a larger muscle or muscle bundle. These in turn can pull on tendons and ligaments associated with the muscle and can cause pain deep within a joint where there are no muscles. The integrated hypothesis theory states that trigger points form from excessive release of acetylcholine which produces sustained depolarization of muscle fibers. Indeed, the trigger point has an abnormal biochemical composition with elevated concentrations of acetylcholine, noradrenaline and serotonin and a lower pH. These sustained contractions of muscle sarcomeres compresses local blood supply restricting the energy needs of the local region. This crisis of energy produces sensitizing substances that interact with some nociceptive (pain) nerves traversing in the local region which in turn can produce localized pain within the muscle at the neuromuscular junction (Travell and Simons 1999). When trigger points are present in muscles there is often pain and weakness in the associated structures. These pain patterns in muscles follow specific nerve pathways and have been readily mapped to allow for identification of the causative pain factor. Many trigger points have pain patterns that overlap, and some create reciprocal cyclic relationships that need to be treated extensively to remove them.
the suboccipital muscles are a group of small muscles located at the base of the skull. These muscles are responsible for small movements of the head and the first two vertebrae. They also play a roll in postural stability of the skull. Trigger points are common in people with poor neck posture. these points will refer pain deep into the skull and behind the eye. They are a common source of headache pain.
the platysma muscle is a thin sheet like muscle in the front of the neck. It functions to pull the edges of the mouth down. Trigger points in this muscle will produce a prickly, pins and needles sensation in the face that is often mistaken for neurological problems.
the pectoralis major is the main muscle of the chest. It is a powerful adductor of the arm. This muscle often is tight and shortened from poor shoulder posture. Trigger points in this muscle will cause pain to refer into the chest, shoulder, and down the arm. Trigger points in the left pec can mimic heart attack and angina symptoms.
The serratus anterior muscle is responsible for scapular and rib movement and stability. This muscle can become overloaded from poor posture of the shoulders, as well as heavy breathing from exertion. Trigger points in this muscle will cause pain to be felt under the armpit into the shoulder blade area, and down the arm into the fingers.