Each wrist has eight carpal bones arranged in two rows. This group of bones joins the long bones in the forearm, which are called the radius and ulna.
The trapezoid, trapezium, capitate, hamate, scaphoid, lunate, pisiform, and triquertrum are the eight carpal bones that make up the carpus, which connects the hand to the arm. These bones work with the muscles and tendons to raise the back of the hand, rotate the forearm, bend the palm downward and bend the wrist toward the thumb or little finger.
The scaphoid is the carpal bone most likely to be injured according to the University of Dartmouth. Falling with a hand outstretched can often cause the bone to break. Another common injury is dislocation of the lunate.