Which carpal bone is sesamoid-like and lies within the tendon of the flexor carpi ulnaris?

Which carpal bone is sesamoid-like and lies within the tendon of the flexor carpi ulnaris?

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

Answer: (A)

The lift in load and angle is achieved by a tendon-friendly feature called a sesamoid. In the wrist, the flexor carpi ulnaris tendon actually contains a small, pea‑shaped bone—the pisiform. This sesamoid-like bone sits within that tendon as it crosses the ulnar side of the wrist, changing the direction of pull and increasing the tendon’s mechanical advantage for flexion. It also helps protect the tendon as it glides over the carpal bones. The other listed carpal bones—lunate, scaphoid, and hamate—are true bones of the wrist that form joints with neighboring bones; they are not embedded in a tendon as a sesamoid. So the bone that fits the description is the pisiform.

The lift in load and angle is achieved by a tendon-friendly feature called a sesamoid. In the wrist, the flexor carpi ulnaris tendon actually contains a small, pea‑shaped bone—the pisiform. This sesamoid-like bone sits within that tendon as it crosses the ulnar side of the wrist, changing the direction of pull and increasing the tendon’s mechanical advantage for flexion. It also helps protect the tendon as it glides over the carpal bones. The other listed carpal bones—lunate, scaphoid, and hamate—are true bones of the wrist that form joints with neighboring bones; they are not embedded in a tendon as a sesamoid. So the bone that fits the description is the pisiform.