On a wrist radiograph, which bone is identified by structure D?

• A. Pisiform
• B. Lunate
• C. Triquetral
• D. Hamate

Answer: (A)

This question tests your ability to identify carpal bones on a wrist radiograph, focusing on a small, rounded bone that sits on the ulnar side of the proximal carpal row. That structure corresponds to the pisiform, a sesamoid bone embedded in the tendon of flexor carpi ulnaris and lying on the palmar surface just above the triquetrum. Its distinctive, pea-like shape and its position at the base of the palm on the ulnar side make it recognizable as the pisiform on a wrist image. Other carpal bones have different shapes and locations—lunate is centrally located and moon-shaped, triquetrum is larger and behind, and hamate is a hook-shaped bone in the distal row toward the ulna—so the small, round structure on the ulnar side points to the pisiform.