In the Postural Respiration manual on page 50, “Considering BC test reasoning”, on the column titled: Right Scapula it has a bullet that says “resting in a protracted state (Rib hump) - if in a retracted state, indicative of compensation from right subclavius”. What does it mean by compensation from subclavius and under what circumstances?
The Right scapula has muscles specifically designed to retract it. The primary muscles of retraction would be the posteriorly positioned middle and lower trapezius. Occasionally the right subclavius (because of its attachment sites) can begin to assist in scapular retraction even though it is on the front of the body. As the scapula moves forward the right mid and lower trapezius becomes mechanically disadvantaged and the subclavius becomes more powerfully positioned as a scapular retractor because of position.
So as the clavicle move forward the muscle attempts to retract it. This can become even more significant in superior T-4 patients as the upper ribs elevate and bump up against the clavicle.