Lines of action and stabilizing potential of the shoulder musculature

Abstract

The objective of the present study was to measure the lines of action of 18 major muscles and muscle sub-regions crossing the glenohumeral joint of the human shoulder, and to compute the potential contribution of these muscles to joint shear and compression during scapular-plane abduction and sagittal-plane flexion. The stabilizing potential of a muscle was found by assessing its contribution to superior/inferior and anterior/posterior joint shear in the scapular and transverse planes, respectively. A muscle with stabilizing potential was oriented to apply more compression than shear at the glenohumeral joint, whereas a muscle with destabilizing potential was oriented to apply more shear. Si..