The bony projection of the ulna at the elbow

• A. Olecranon
• B. Trochlea
• C. Coronoid process
• D. Olecranon fossa

Answer: (A)

The olecranon is the prominent posterior projection at the proximal end of the ulna. It forms the point of the elbow and serves as the attachment for the triceps brachii tendon, enabling elbow extension. It also fits into the olecranon fossa of the humerus when the elbow straightens, stabilizing the joint. The other structures are not projections of the ulna at the elbow: the trochlea is a distal humeral pulley that articulates with the ulna’s notch; the coronoid process is a smaller anterior projection on the ulna that articulates with the humerus during flexion; the olecranon fossa is a depression on the humerus that accepts the olecranon during extension.