Joints are meeting points between two bones. Some common joints are actually a complex of multiple joints. At the wrist, the radius articulates with the ulna, the proximal carpal bones articulate with both the radius and the ulna, and the distal carpal bones articulate with the proximal carpal bones. This allows for sophisticated and fine movement control, but requires many muscles to operate. The wrist can flex, extend, radially deviate, and ulnarly deviate. Wait till you think about all that your hand can do!
