Broken wrist. Coloured X-ray of a fracture (red) of the scaphoid bone in the wrist. The scaphoid is a small cashew nut shaped bone (upper left) located where the thumb joins the wrist. This is the most frequently injured carpal (wrist) bone. The majority of these fractures occur in young men. A fractured scaphoid usually results from a fall on an outstretched hand. Distal and horizontal fractures usually heal well during immobilization in a short-arm thumb cast. The scaphoid is crucial to the intricate function of the wrist.