Pain and limited motion in the shoulder is a very common musculoskeletal complaint. Its frequency is second only to low back pain. The onset is usually insidious but there is usually some history of a past injury. Most of us tear the rotator cuff of the shoulder at some point in our youth and most of us have forgotten the injury. As we age, this old injury often comes back to haunt us.
The rotator cuff is a group of muscles that support the shoulder and create movement. They are, in order of importance, the supraspinatous, infraspinatous, serratus anticus, teres minor, and subscapularis.
The shoulder is an unusual joint in that there are no ligaments to hold the humeral head to the glenoid fossa of the shoulder. So it is the rotator cuff muscles that hold the arm into the socket. To facilitate this process, the supraspinatous contracts constantly, even in your sleep. It is the only skeletal muscle in the body that does so. If the supraspinatous is weak, the arm actually dislocates from the shoulder. This commonly occurs during sleep and is often the cause of chronic shoulder pain. Strengthening the supraspinatous is the key to resolving most shoulder problems.
Constant contraction of the supraspinatous requires ongoing input from the nervous system, so weakness of the supraspinatous can be an indicator of brain imbalance. The supraspinatous is used in Applied Kinesiology (AK) to evaluate the limbic portion of the brain, specifically its relationship with the endocrine system.
In similar fashion, the teres minor is related to the thyroid gland. So weakness of the teres minor may indicate thyroid imbalance. Monitoring teres minor weakness is also used in AK to evaluate the endocrine system.
The shoulder is also a common site for referred pain. In cardiac insufficiency, pain is often referred from the heart to the left shoulder and down the left arm. Gallbladder inflammation will refer pain to the right shoulder in a similar fashion. When evaluating shoulder pain these referred pain pathways must always be considered, even when there is a strong history of injury.
