Jan 9, 2023 | Blog | 0 comments

For some reason, I have decided to write a blog explaining some common concepts of shoulder pain. For those that have some degree of anatomy knowledge will know that this is an absolute minefield. Here’s why:

The shoulder is one complicated piece of kit. It’s designed to maintain structural integrity without loosing mobility. Usually the two don’t match up well without layers and layers of complexity.

The shoulder girdle is also prone to a large amount of systemic diagnosis; from pseudo gout to adhesive capsulitis (frozen shoulder). So, for this blog, and for the sake of simplicity, we are going to focus purely on Musculo-Skeletal issues that arise as a result of mechanical dysfunction.

For us to understand function, we ned to understand its structure – after all, structure governs function, and function governs structure!

The shoulder girdle includes the shoulder blade (and its articulation with the rib cage), the collar bone, and the humerus. These bones need to harmoniously articulate with each other in order to create the movements that we rely on to live.

The collar bone needs to articulate with the shoulder blade nicely to allow isolated rotation of the humerus. The Humerus needs to articulate nicely with the shoulder blade to allow initial movement of the arm, and more importantly, (and more commonly doesn’t work properly leading to a whole host of issues) the shoulder blade needs to slide against the rib cage.

The shoulder isn’t just the ball and socket joint of the arm connecting to the shoulder blade. This only accounts for about 40% of movement in the shoulder girdle. If you lift your arm away from your body, the ball and socket joint we all know as the shoulder only actually accounts for movement up to about 90 degrees forwards, backwards, and to the side. The rest of it comes from how the shoulder blade slides against the back.  To me, the most important thing to consider is something called Scapulo-Thoracic engagement. This is how the shoulder blade slides against the rib cage – it’s actually this movement that allows us to lift our hands above our heads, to reach for the top cupboard, to put clothes on our back and to maintain good posture – important movements for any kind of quality of life!

Scapulo-thoracic engagement is something that allows for minimal strain through the rotator cuff. You’ve all probably heard of this ominous thing called the rotator cuff. Friends and family at some point have more than likely had tears and strains to the rotator cuff:

The rotator cuff is actually a collection of 4 muscles. 4 muscles that sit on and around the shoulder blade. They all attach into and around the top of the humerus, like a cuff, that allow us to do rotation-y things with our arm…. It’s an imaginative name.

Like with most joints in the body, muscles struggle when there isn’t fluid movement through the joint and the local skeletal system isn’t moving as well as It can be. A bit like how you’d burn out your clutch and engine if you tried to repeatedly drive a car that had its hand-break on.

When it comes to rotator cuff strains, the most common root cause is due to overuse due to lack of scapula-thoracic engagement. The reason why this happens comes down to posture.

If your shoulders are always jutting forward and your upper back is always rounded. The shoulder blade is already pushed to a limited range of motion, which is absolutely not conducive to good scapulo-thoracic engagement. Whilst you are sitting there reading this, try this out. Push your shoulder forward and try and lift your arm out to the side so that your hand is higher than your shoulder. It’s not comfortable and it’s pretty difficult to do!  Now try the same movement with your shoulders back and your shoulder blades squeezed together – it’s a nice, easy fluid movement – Get it?!

Posture is ESSENTIAL for scapulo-thoracic engagement, and scapula-thoracic engagement is essential for fluid movement of the shoulder girdle!

Another VERY common issue I see is that involvement of the biceps tendon. This muscle splits into two and has two separate attachments into the shoulder. The short head runs up into the front of the shoulder just under the end of the collar bone. The Long Head of biceps actually runs up and into the shoulder joint itself, and onto the edge of the socket of the ball and socket joint. Where this muscle attaches, it lies directly under a tendon of one of the rotator cuff. Therefore, when one of these muscles is angered, the other is as well.

In fact, the long head of biceps accounts for way more shoulder issues than it gets credit for. biceps is actually a large factor in most rotator cuff strains. Whether it be from trauma or from overstrain and tension, the long head of biceps gets a lot of pressure put on it.

When we lift our arm up away from the body (abduction), a knobbly part of the humerus comes into contact with the top of the shoulder blade. This is where shoulder blade movement against the back takes over to allow function of the arm above the head. This is also exactly the gap where the biceps tendon comes into the socket of the shoulder joint. If this tendon is thickened due to chronic tension and/or inflamed from a strain, then as you close that gap, it’ll pinch the biceps tendon, and give a pretty nasty “catching pain” and weakness in the arm.

As usual, a holistic approach is always needed, and it’s important to not get bogged down in a reductionist diagnosis. What’s important is finding out why. Once again, function from postural function is hero here. So, for those that have shoulder pain and issues with gross movement of the arm. Take a look at posture and go about fixing it!


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