/ = bicipital groove, G= greater tubercle, L= lesser tubercle, X= deltoid insertion
SUB= Subscapularis, SUP= Suprispinatus, I= Infraspinatus, T= Teres Minor
Shoulder case
Mary has pain and can't lift her arm out to the side. What muscles might be involved in this dysfunction?
Deltoid and Suprapsinatus both abduct the shoulder, so I would expect one of them.
You palpate her shoulder
and find that she is quite tender just inferior to her acromion, now what structure(s) do you suspect?
It is more likely that Supraspinatus has been compromised as it inserts just below the acromion.
Since Mary can't raise her humerus, but still must reach over her head from time to time, she might have to substitute. What other muscles could she try to use to accomplish the task of raising her arm over her head?
I would recommend that Mary try to flex her humerus with her bicep and then use the posterior fibers of her deltoid to help bring her arm out to the side.
Nice work, Jen. High-level catch there pointing out how the posterior deltoid might be used to substitute. This does happen in clinical practice. It is a poor substitution, but sometimes it is all patients can do when the Rotator cuff is involved. We usually see this more happening when the Infraspinatus and Teres Minor are involved. Can you see why?
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