The empty can test primarily assesses the function of which structure?

The empty can test primarily assesses the function of which structure?

• A. Supraspinatus
• B. Infraspinatus
• C. Teres minor
• D. Subscapularis

Answer: (A)

The primary structure tested here is the supraspinatus. In the empty can position, the arm is in the scapular plane with internal rotation (thumbs pointing downward) and the patient resists downward pressure. This setup places the supraspinatus in a position where it must initiate and sustain first-degree abduction against resistance, while the deltoid is less effective in this posture. A weakness or pain during the resisted elevation indicates supraspinatus dysfunction, commonly due to tendinopathy or tear. The other muscles listed—external rotators and internal rotators—aren’t the main structures stressed by this maneuver, which is why this test specifically targets the supraspinatus.

The primary structure tested here is the supraspinatus. In the empty can position, the arm is in the scapular plane with internal rotation (thumbs pointing downward) and the patient resists downward pressure. This setup places the supraspinatus in a position where it must initiate and sustain first-degree abduction against resistance, while the deltoid is less effective in this posture. A weakness or pain during the resisted elevation indicates supraspinatus dysfunction, commonly due to tendinopathy or tear. The other muscles listed—external rotators and internal rotators—aren’t the main structures stressed by this maneuver, which is why this test specifically targets the supraspinatus.