The trochlea is part of which bone?

• A. Clavicle
• B. Ulna
• C. Radius
• D. Humerus

Answer: (D)

On the distal end of the humerus there is a spool-shaped articular surface called the trochlea. It meets the ulna at its trochlear notch, forming the elbow joint and allowing the hinge movement of bending and straightening the arm. The radius does not connect with the trochlea (it articulates with the capitulum of the humerus), and the clavicle is part of the shoulder girdle, not the elbow. So the structure described as the trochlea belongs to the humerus.