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The Scapula Ribcage Interface

Updated: Dec 14, 2023

The scapula ribcage interface

Social media has taken to the ribcage like a festive gingerbread spiced pumpkin latte in December. It is indeed the current flavour of the month when it comes to conversations about the shoulder. 


It seems nausing off on the rotator cuff has become somewhat uncool. Popular attention has instead shifted to the ribcage and is it now being purveyed as the new holy grail of shoulder function. 


Pitching your flag on this hill however puts you in a precarious position. It’s called the Wylie Coyote effect. The protagonist is so committed to his or her cause that they’ve run off a cliff and found themselves suspended in mid-air, only to look down and realise there is no ground to stand on. 


Many have failed to embrace the complexity of the shoulder and instead run off the ledge of Reductionism. 


Reductionism: ‘The practice of considering or presenting something complicated in a simple way, especially a way that is too simple.’


I should note there is nothing wrong with reductionism. Often, we need it to understand ‘parts’, but you can’t stay there. You must take what you now comprehend and zoom out in order to fathom the whole. 




The ribcage is a part. 


It’s an important part because it articulates with the scapula to create the scapulothoracic joint, and with the clavicle to create the sternoclavicular joint. 


The position of the ribcage is affected by the curvature of the spine, and the position of the scapula on the ribcage impacts the glenohumeral joint. 


Clearly its function has a causative effect on shoulder performance.  


Seeing that it carries all this weight, all we probably need to do is some breathing drills and that will resolve all shoulder problems?

No. Long term solutions will require more integrated thinking than this.




The human body does not function in parts.


We can help simplify the complexity and start building our comprehension of the shoulder by understanding interfaces.


Interface. noun:

1. The point where two systems, subjects or organisations meet and interact.

2. A situation where two things come together and affect each other.  




As the understanding of the kinetic chains’ role in shoulder function has become better understood, the laser focus on scapulohumeral rhythm has broadened, and rightly so. 


We can’t however forget that the scapula is the linchpin and plays a pivotal role in transferring forces generated by the lower body and core to the hand. How it moves remains a key contributing factor to the performance of the upper limb. 


The complexity of the shoulder is increased because the scapulothoracic joint is not a true anatomic joint. Rather than having a capsule or other cartilaginous/fibrous tissues, it is positioned almost entirely by muscle forces. 


Here is where the scapula - ribcage interface comes in. 


The scapula slides and glides over the ribcage courtesy of the concave-convex shape compatibility.


In a well-functioning shoulder, the ribcage acts as a ‘guide’ for the scapula. To quote Eric Cressey, the scapula is the train which sits on the tracks of the ribcage. 


Scapulothoracic joint motion is therefore not only affected by the extensive periscapular and glenohumeral joint musculature. There is something else at play.


Let me give you an example.


You might have heard the term ‘winging scapula’. This occurs when the train isn’t siting optimally on the tracks. 


Biomechanically what this means is a portion of the scapula is not in seated properly on the ribcage leading to a decrease in scapulothoracic control and stability. 


One cause of a winging scapula is a lack of balanced muscle forces around the shoulder.


Another could be that the shape of the spine means the ribcage has moved away from the scapula. 


We see this in swimmers, powerlifters and those who have taken the ‘stand up straight’ military posture one step too far. 


Through years of repeated thoracic extension the spine can lose its natural curvature causing the mid-back to flatten. 


In this case, the curvature of the spine shifts the ribcage position. So instead of putting the scapula on the ribcage, we need to put the ribcage on the scapula. 


How do we do that? 


By mobilising the spine into flexion patterns and encouraging posterior expansion of the ribcage which can be done through breathwork.  




The spine affects rib cage position, which affects scapula function, which affects the articulation with the humerus, which affects the brain’s ability to position the hand in space. 


So, should we think about improving ribcage position and function?




Is it all that matters? 




We’d be silly to not also think about other things that allow the shoulder to function optimally which I have discussed in other blogs. You can start with 'Five big rocks to scaling shoulder performance'.


If you’ve been to enough conferences, sooner or later someone is going to flash up a slide of a number of people in blindfolds fondling different parts of an elephant, all thinking they know what is it, all thinking something different. None of them correct.

The blind and the elephant

Be aware of people telling you the ribcage is all that matters for shoulder function. 


They are elephant fondling blind men.


Function of the shoulder is an intricate affair so you really can’t think about it in isolation. 


It’s not just the ribcage, nor is it just the scapula, or the rotator cuff. 


It’s all of it. 


Plus the spine, the pelvis, knee, ankle and of course most importantly, the brain. 


Kick-start your journey to stronger, more stable shoulders you can trust.

Are you frustrated with banged-up shoulders?

Are your shoulders restricting your training and progression?

Are you looking to enhance your upper body performance in sport, CrossFit, calisthenics or other gym-based strength training?

Take a look at our 6-week BASE online shoulder training programme.

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