Which of the following statements are true about the carpal bones?
1. They are arranged into proximal, middle, and distal rows.
2. The scaphoid, lunate, pisiform, and triquetrum represent the distal row of the carpal bones.
3. They provide the attachment to the flexor retinaculum.
4. Their proximal row forms the joint with the ulna.
5. All of the above are true.