Muscle activities during shoulder internal rotation differ in arm position: a preliminary quantitative analysis using positron emission tomography

ConclusionsThe middle and inferior parts of the subscapularis are the main shoulder internal rotators in 0 ° of abduction, whereas the inferior part of the subscapularis is the main internal rotator in 90° of abduction.
Source: Skeletal Radiology - Category: Radiology Source Type: research