Which structure locks into the intermediate tubercle of the humerus?

Which structure locks into the intermediate tubercle of the humerus?

• A. Supraspinatus tendon
• B. Infraspinatus tendon
• C. Deltoid tendon
• D. Biceps tendon

Answer: (D)

The key idea is how tendons interact with the humerus at the shoulder region. The long head of the biceps brachii travels into the bicipital (intertubercular) groove, which lies between the greater and lesser tubercles of the humerus. That groove, reinforced by the transverse humeral ligament, forms a canal that holds the tendon in place as the arm moves, effectively “locking” the tendon into the region around the intermediate tubercle. The other tendons attach to the greater tubercle or to the deltoid tuberosity and do not reside in this groove, so they don’t lock into the intermediate tubercle. Therefore, the structure that locks into the intermediate tubercle is the tendon of the long head of the biceps brachii.

The key idea is how tendons interact with the humerus at the shoulder region. The long head of the biceps brachii travels into the bicipital (intertubercular) groove, which lies between the greater and lesser tubercles of the humerus. That groove, reinforced by the transverse humeral ligament, forms a canal that holds the tendon in place as the arm moves, effectively “locking” the tendon into the region around the intermediate tubercle. The other tendons attach to the greater tubercle or to the deltoid tuberosity and do not reside in this groove, so they don’t lock into the intermediate tubercle. Therefore, the structure that locks into the intermediate tubercle is the tendon of the long head of the biceps brachii.