Humerus:The long bone in the upper arm that extends from the shoulder to the elbow.
Ulna:One of the two long bones in the forearm, situated on the side opposite to the thumb and articulating with the humerus at the trochlea.
Elbow Joint:A complex hinge joint between the end of the humerus and the ends of the radius and ulna, allowing for flexion and extension of the forearm