Question: Musculoskeletal, Skin & Subcutaneous Tissue
A 54-year-old woman comes to the physician because of a 1-week history of right shoulder pain that is worse when she lifts objects above her head and at night when she lies on the right side. There is no history of trauma. On examination there is tenderness over the lateral shoulder, a full passive range of motion, and pain and weakness on active abduction that is most pronounced during initiation of abduction. Which of the following muscles is most likely affected?
Choose one answer.
Explanation
Correct answer: D. Supraspinatus
Pain with overhead activity, weakness on initiating abduction, and preserved passive motion point to a supraspinatus problem; the supraspinatus initiates the first roughly 15 degrees of abduction and is the most commonly injured rotator cuff muscle. The infraspinatus and teres minor produce external rotation, the subscapularis produces internal rotation, and the deltoid takes over abduction beyond the initial arc.
Learning objective: Localize rotator cuff pathology affecting abduction to the supraspinatus.
Want this back right before you'd forget it?
Ebb Deck brings back 1,500 USMLE Step 1 questions like this one with spaced repetition, on the web and on iPhone. Your first 100 are free.