NBME 23 Answers ↦
I was thinking along the lines of overhead motion - damage to the subacromial bursa which is between the acromion and the supraspinatus ... also its the most commonly injured rotator cuff m. so could have guessed this one right
Thanks for the explanation. I was scratching my head as to why this is correct, since supraspinatus only does 15 degrees of abduction, but you make a lot of sense.
why would injury to supraspinatus cause weakness with internal rotation though?
yeah coz of that i picked subscapularis
ya the whole question pointed to supraspinatus ...but last line internal rotation made me pick subscapularis
I went for Trapezius. That shoulder flexion thing was a big distraction. Silly me.
FA2019 pg. 438
Deltoid only does abduction from 15 to 90 degrees. So not overhead.
With that logic, supraspinatus only does abduction form 0-15
the positive empty can test is the biggest thing "pain and weakness with abduction, particularly with simultaneous shoulder internal rotation" - that tells you it has to be one of the SITS muscles (supraspinatus, infraspinatus, teres minor, subscapularis), not the deltoid.
tenderness in the right deltoid region tells you it's the supraspinatus which is right underneath the deltoid muscle