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Movements of the Shoulder Girdle

Our shoulder is a very unique joint, as its base of a support is basically a giant sesamoid bone (bone within the substance of muscle), the scapula. But we need to clear some things up, and delineate between the two moving joints of the shoulder.


First, let's start with the more well-known Glenohumeral joint. A fun tip: the name of a joint typically tells you which two bones are interacting. In this case, we have the glenoid fossa of the scapula articulating with the head of the humerus. The glenohumeral joint is a ball & socket joint, meaning it can move in all three planes of movement: sagittal, frontal & transverse. Let's break down what movements occur in each plane.


-Sagittal: flexion & extension

-Frontal: abduction & adduction

-Transverse: internal & external rotation

Now we move posteriorly to the Scapulothoracic joint. The scapula, otherwise known as our shoulder blade, sits on top of the posterior aspect of rib cage/thorax. This bone moves and glides over the top of our ribs. Whenever our shoulder moves, the scapula moves too. In fact, there is a concept termed scapulohumeral rhythm that states for every 2 degrees of shoulder movement, there is 1 degree of scapula movement. Here are the scapula movements in each plane:


-Sagittal: protraction & retraction, anterior & posterior tilting

-Frontal: upward & downward rotation

-Transverse: medial & lateral tilting

This is a birds-eye view of the various movements at the shoulder girdle. Heck, we didn't even talk about muscles yet. But it's important to know the movements, before you learn the muscles and their actions.



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