This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Pisiform is which type of bone: 
Select and explain. 
A. Pneumatic bone, B. Sesamoid bone, C. Accessory bone, D. Long bone
B: Sesamoid bone
Answer: B: Sesamoid bone 
Explanation: The pisiform is a sesamoid bone, with no covering membrane of periosteum. It is the last carpal bone to ossify. 
The pisiform bone is a small bone found in the proximal row of the wrist (carpus). 
It is situated where the ulna joins the wrist, within the tendon of the flexor carpi ulnaris muscle.