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Shoulders That Sing: The Shoulder Is Really a Complex

I know I write this about every joint in the body, but shoulders are truly one of my very favorite body parts to work with!

Shoulder injuries and pain are so common- everyone from overhead athletes to couch potatoes can experience shoulder pain in their lifetime- I think it is important we take a good minute to soak in what we presently know about the shoulders, and practices to keep them healthy.

Over the course of the next month, we will examine the following topics as they relate to our beautiful shoulder joints:

  1. The shoulder is really a complex (a series of 4 joints) instead of just one joint

  2. There is a symbiotic relationship between our mid back (thoracic spine), our ribs and our shoulder function

  3. The ball and socket joint of our shoulder (aka our glenohumeral joint- GH joint), is greatly challenged in stability and the rotator cuff is a wonderful series of 4 muscles and tendons specifically designed to help our GH joint maintain stability

  4. Your shoulder has a rhythm

I am excited for each of you to cultivate more awareness of your incredible shoulders, and to get shoulders that truly sing! Let’s get started this week by exploring the anatomy of the four joints that make up the shoulder complex.

  1. The Shoulder Is Really a Complex

Reflect for a moment on all of the things you have heard over the years to maintain shoulder :

“stand up straight, pull your shoulder blades together, motion is lotion”

Some of these statements have truth to them. But to know how to better care for our shoulders, we must understand that our shoulders are composed of four very different joints, that require different movement strategies. We need to move beyond a global approach, and develop a more nuanced approach to how we care for our shoulders.

1. Sternoclavicular joint: a saddle shaped planar joint. This is the only joint in the shoulder complex that connects the shoulder with the axial skeleton. Take that in! This concept alone allows you to understand just how greatly the shoulder struggles with creating stability.

2. Acromioclavicular joint: Planar joint between the scapula (shoulder blade) and the clavicle (collar bone). Some of the strongest ligaments in the body- the acromioclavicular ligaments- limit motion across this joint.

3. Glenohumeral joint: Articulation between the round head of the humerus and the shallow depression of the acromium on the shoulder blade. The joint is strengthened and deepened by the labrum, special cartilage that forms a seal between the two bones. This is a ball and socket joint, similar to the hip joint. Ball and socket joints allow for maximal planes of motion.

4. Scapulothoracic joint: One of the only joints in the body (if not the only) that does not exist between two bones- it is made up of the connection between the thin triangular scapula (the shoulder blades) and muscles and bones of the rib cage that connect underneath it. The scapulothoracic joint is the foundation for success for the rotator cuff- it determines the resting position of the glenohumeral joint as all of the muscles of the rotator cuff arise from the


Because the glenohumeral and scapulothoracic joints have the most movement, we will spend the majority of our vacation in shoulder land looking into the movement and function of these two critical joints.

It is beyond the scope of our workshop to delve more deeply into how each of these joints moves (e.g. circumduction, planar glides etc.- although, we might explore a bit of that info with relationship to scapulohumeral rhythm). For more information on the biomechanics of each of the shoulder joints, please refer to your ever helpful functional anatomy text (such as Clinically Oriented Anatomy by K. Moore, et al.).

**The type and shape of the joints, the ligaments surrounding them, and the muscles attaching near and around govern how each of the joints move. This field of study has already been well flushed out, and is known as arthrokinematics. In arthrokinematics (unlike biomechanics) we are generally not considering the forces acting across the structures of a joint.

I have likely given the cue- lift your arms overhead and keep your ribs stable. Next week, we will see if that is actually possible, or if I am suggesting the impossible. In week two of exploring Shoulders That Sing, we will dive into the interconnectedness between the mid back (thoracic spine), the ribs and our shoulder alignment and function.

By the way, during this shoulder exploration, I will be using some of the anatomically correct terms. I feel like they are important to use for accuracy. If your anatomy is rusty, or it feels frustrating to encounter a term you are not familiar with, read ahead and let it wash over you. Don’t worry too much about it. Learning anatomy is like learning a whole new language- and you will get more skilled with interest and time.

Until next time, happy moving!


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