Just to add more ambiguity to this type of injury heres a few more notes. no reply needed…
External rotators
-Deltoid muscle :: damaged in posterior cord palsy
-Supraspinatus :: ok
-Infraspinatus :: ok
-Teres minor :: damaged in posterior cord palsy
Internal rotators
-Anterior part of the deltoid muscle :: damaged in posterior cord palsy
-Subscapularis :: damaged in posterior cord palsy
-Teres major :: damaged in posterior cord palsy
-Latissimus dorsi :: damaged in posterior cord palsy
-Pectoralis major :: ok
I image the pec being larger and stronger than the remaining supra/infraspinatus, but this is in the weeds.