Wisdom Wednesday: The Shoulder

Shoulder pain is a very common clinical complaint, second only to low back pain in frequency. Research indicates that most of us tear our rotator cuff (the group of muscles that support the shoulder joint) sometime in our lives and most of us actually forget the injury.

I guess I’m not like most people because I vividly remember tearing both my right and left rotator cuff even though the first injury was 45 years ago.

The shoulder joint is very complex. It is a little like the hip joint but is designed with much greater range of motion but can’t tolerate constant weight bearing. There are no ligaments in the joint proper. Ligaments attach bone-to-bone. So the head of the humerus (upper arm) is suspended from the glenoid fossa (shoulder socket) by a series of tendons attached to the rotator cuff muscles.

Think of the humerus as the gondola on a hot air balloon. As long as all the cables (tendons and muscles) are even in strength and tension, the balloon sits level. However, shorten or break even one of those cables and the gondola will lurch to one side. When the humerus is riding unevenly in the socket, inflammation and subsequent degeneration occur.

To complicate matters, when the shoulder is lifted above level, the clavicle (collar bone) and scapula (wing bone) both elevate to change the shape of the joint allowing even greater range of motion.

The four rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. Each one acts to strengthen and facilitate motion in the shoulder but all have their unique evaluation and treatment issues.

Wisdom Wednesday: The Shoulder

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.