In our second week, we looked at how our ribs and mid back allow the arm to move more fully overhead. Each of the four joints that make up the shoulder complex (plus the surrounding joints of the ribs and mid back) affect one another, and affect our upper extremity movement production. This week, let’s look at how our mid back and rib posture affects our shoulders, and how our shoulder blade (also known as our scapula) contributes to our movement production.
Your shoulder blade has rhythm
Imagine your thin, triangular, incredible shoulder blades. Such an unusually shaped bone, with not a tubercle, spine or foramen wasted! The shoulder blade is perfectly adapted to perform its functions- orchestrating healthful movement of the upper extremity (along with all of the other bones of the shoulder complex).
Posture is key for shoulder blade function. The postural alignment of our mid backs, sets the foundation for our scapulothoracic joint (after all, it is the “thoracic” part of the equation). When we rest in kyphosis at our mid backs, not only do we not allow the vertebra to weight bear optimally (exposing our thoracic vertebra to bony fatigue), we also shift the shape of our shoulder blades. In kyphotic posture, our shoulder blades tend to tip forward (anterior tilt) allowing their inferior tips to move away from our body, and we tend to have the shoulder blades migrate apart (protract).
Good posture also contributes to the always important issue- healthy length and tension relationships- of the 10 major muscles that attach to the shoulder blade. Recall, all four of the rotator cuff muscles arise from the shoulder blades, before they insert around the ball of the humerus.