The Shoulder Complex

May 24, 2021 • Physiotherapy

Let’s take some time to break down the shoulder. We’re going to take 2 weeks to focus on this amazing joint- there’s a lot to it!

The Shoulder Complex. A name that is quite true to its structure. The shoulder is not only where the head of the humerus (arm bone) meets the socket of the scapula (shoulder blade). It is actually made up of 3 main components. Let’s talk about what these 3 parts are, what optimal function looks like, and what can happen when these things are not functioning optimally.

The shoulder complex is made up of the glenohumeral joint (the shoulder joint), which is where the head of the humerus sits inside the socket of the scapula. It also includes the scapulothoracic joint (the shoulder blade), which technically, is a floating joint. Meaning that there is no true articulation between two bones, but the joint is actually held together by muscular tissue. Lastly, the shoulder complex includes the ribcage and the thoracic spine.

As the song goes, the arm bones connected to the.. shoulder blade. The shoulder blades connected to the.. rib cage. The rib cage is connected to the.. vertebrae.

Shoulder Work  Port

If we think about how intricately everything is connected, how could the function of one component NOT effect the function of all the others?

The shoulder joint is surrounded by a fibrous capsule. This capsule can be thought of like a piece of saran wrap that encapsulates the joint and provides support, but it MUST allow for movement. This structure, along with the muscles surrounding the joint can become stiff, which can result in a lack of mobility and movement around the joint. This would look like a decreased ability to reach up above your head, out to the side of your body, shampoo your hair, or reach around your back to tuck in your shirt.

The shoulder blade (Scapulothoracic Joint) ensures that the shoulder joint has somewhere to sit. The scapula is held in place on the ribcage by various muscles and other soft tissues. If these muscles are tight or weak, the result can be a scapula that doesn’t move. As we have discussed, it is much harder to move the shoulder joint, without movement further up the chain. The scapula allows us to do things like shrug our shoulders to our ears, stand up tall like a soldier in line, throw a ball and do a push up. If the scapula was glued down to our ribcage and unable to move, all of these things would be next to impossible.

Lastly, since the shoulder blade sits on the ribcage, we have to talk about it! The ribs are attached to the thoracic vertebrae of the spine, or the mid back. As I mentioned in an earlier article, the spine is meant to move in every direction, including flexing forward, extending back, bending side to side, and rotating. If the spine cannot do these things, the ribs will surely lack that movement. In turn, this will result in the scapula and shoulder joint being unable to move to their full potential.

Stay tuned for part two next week! We'll apply all of the above information to real life!