In wrist anatomy labeling, structure E represents which bone?

• A. Hamate
• B. Trapezium
• C. Trapezoid
• D. Capitate

Answer: (B)

Understanding how to identify wrist carpal bones on a labeled diagram is key. The structure at the thumb-side end of the distal carpal row that forms a joint with the base of the first metacarpal is the trapezium. This bone is the most lateral of the distal row and has a saddle-shaped articular surface to accommodate the thumb’s metacarpal, which is a distinctive feature you can use to recognize it on diagrams.

The other bones occupy different positions and have different relationships: the capitate sits more centrally in the distal row, the trapezoid lies just medial to the trapezium and articulates with the index finger’s metacarpal, and the hamate is on the ulnar side with a hook-like hamulus. So the labeled structure matching the thumb-side distal carpal bone that interacts with the first metacarpal is the trapezium.