Napoléon's sign is used to assess weakness in which muscle?

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

Answer: (C)

Napoléon's sign, or the belly press test, specifically assesses the subscapularis muscle, the main internal rotator of the shoulder. In this test you have the patient place the palm on the abdomen and press the hand into the belly. A healthy subscapularis allows smooth internal rotation and a firm press. If the subscapularis is weak or torn, the patient cannot maintain internal rotation during the press, often showing compensatory movement with the shoulder or scapula or relying on other muscles like the pectoralis major. This makes the test able to detect subscapularis dysfunction, whereas the other rotator cuff muscles govern external rotation or abduction and are not primarily evaluated by this maneuver.