The bones of the palm (the five metacarpals) are connected to two bones of the lower arm (radius and ulna), through the wrist joint. The wrist joint consists of eight small bones arranged in two rows of four each. These bones are held together tightly through ligaments. The carpal bones form a small opening called the carpal tunnel. Through the tunnel travels the median nerve that controls the movements of the fingers and the thumb. The radius and the ulna bones comprise the forearm and join with the humerus (bones of the upper arm) at the elbow joint.