Which is the insertion of the subscapularis?

• A. Intertubercular groove
• B. Greater tubercle of the humerus
• C. Deltoid tuberosity
• D. Lesser tubercle of the humerus

Answer: (D)

The insertion of the subscapularis is the lesser tubercle of the humerus. This muscle sits on the anterior surface of the scapula and its tendon travels to attach on the small bump on the front of the proximal humerus. This placement lets the subscapularis medially rotate the arm and help keep the humeral head centered in the glenoid during movement, acting as a stabilizer of the shoulder joint. The other landmarks mentioned aren’t tied to the subscapularis insertion: the intertubercular groove is where the long head of the biceps brachii runs, the greater tubercle is the insertion point for the other rotator cuff muscles, and the deltoid tuberosity is where the deltoid attaches along the humeral shaft.