Suprascapular paralysis, causing back pain, problems with abduction and external rotation of the humerus, and wasting away of supraspinatus and infraspinatus. Supraspinatus muscle helps in 0°-15° arm abduction. And Infraspinatus helps in lateral rotation (external rotation) of humerus.
Suprascapular nerve entrapment syndrome, causing shoulder pain and localized muscular atrophy of the supraspinatus and infraspinatus muscles. This can potentially develop due to suprascapular nerve being entrapped and compressed within the suprascapular canal potential anatomical entrapment sites.[1]
Additional images
Suprascapular and axillary nerves of right side, seen from behind.
Brachial plexus with courses of spinal nerves shown