Empty can test supraspinatus

[arda]

The question is attached.Why not deltoid ? is not it responsible for abduction of the arm above 15 degrees?

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[Enzymes]

It's a slightly tricky question. Here is the point: there is no way you can abduct your arm to 90 degrees if your deltoid is fried. So the fact that the patient was able to do that eliminates deltoid.

 

[arda]

Hmm that makes sense and eliminates deltoid,still does not explain how emty can test works,would not it be more logical to do this test at 15 degree?

 

[thehundredthone]

Hmm that makes sense and eliminates deltoid,still does not explain how emty can test works,would not it be more logical to do this test at 15 degree?

15 degrees of shoulder abduction or 15 degrees of shoulder flexion? Although the isolation of the supraspinatus in the manoeuvre has been questioned (and even the function of the muscle altogether), the position of the empty can is supposed to maximally isolate the supraspinatus thereby exposing its weakness on applying resistance.