The humerus is the only bone of the upper arm. It is a long, large bone that extends from the scapula of the shoulder to the ulna and radius of the lower arm. The proximal end of the humerus, known as the head, is a round structure that forms the ball of the ball-and-socket shoulder joint.
I just got it from google normaly i would simplify it but its to simple for me to simplify again hope this helps
