Core Talk: shoulder girdle

We are going to skip the trunk for now. We will talk about that at the end and tie everything together.

For this post, we will focus on the shoulder girdle. I say “shoulder girdle” instead of “shoulder” for a reason. The “shoulder girdle”  encompasses more than just the shoulder joint (glenohumeral joint), it also includes the sternoclavicilar joint (where the clavicle meets the sternum), the Acromioclavicular joint (where the clavicle meets the front of the shoulder blade), and the scapulo-thoracic joint (not really a joint, but this refers to where the scapula, or shoulder blade, moves on the rib cage). That is four different areas that directly affect the shoulder! ALL of these should be considered when treating the shoulder girdle!

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An efficient shoulder is one that has good range of motion in all of the components of the shoulder girdle in all directions, and has a good response from the rotator cuff to “set” the ball in the socket and stabilize the scapula on the rib cage so it does not “wing”. In addition to this, when your arms are loaded, as in lifting objects, an efficient shoulder girdle will allow the trunk to respond by engaging, allowing the shoulder to not work as hard.


An inefficient shoulder is one that is stiff in one or more directions at one or more of the joints that make up the shoulder girdle. It may not have a good “setting” of the ball in the socket due to the rotator cuff not functioning efficiently and/or the scapula may not stabilize well on the rib cage. 


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There are quite a few muscles that would be considered “core muscles” of the shoulder girdle. These would include: the four rotator cuff muscles, and multiple scapular muscles, rhomboids being an important group. 

The rotator cuff muscles are often talked about in the function that each individual muscle performs. However, the beauty of the design of the rotator cuff comes with the synergistic functions off all of them together. They have all been “placed” at specific angles to pull in a way that brings the head of the humerus (ball of the “ball and socket” joint) down and in to the glenoid fossa (socket of the “ball and socket joint”.) This function helps to keep the shoulder moving on its designated axis of motion. Any deviation from that axis, will affect the efficiency of the shoulder girdle. 

There are many possibilities of dysfunctions that can cause the rotator cuff, or any other shoulder girdle “core” muscles to not function as efficiently as they should. We cannot get into all of them in this post, but examples would be: rotator cuff tears, tendonitis of a rotator cuff muscle, impingement syndrome (pinching at the shoulder joint), weakness or imbalances in the musculature surrounding the shoulder girdle, cervical injury (neck pain, pain down the arms, numbness/tingling in the arms/hands.), and more!

There is SO much more that we could talk about here! I want you to be aware of how important it is for your shoulder girdle to function as efficiently as it is able. But also realize that most people are not functioning as efficiently as they could, AND YET they still accomplish many things day to day. It is possible to feel better, move better, be stronger, perform better than what you may be right now! Don’t accept the status quo!