Ulna
The ulna is a long bone that is located in the forearm. There is one ulna in each arm, and they form a part of the appendicular skeleton. The ulna articulates with the humerus and radius to create the elbow joint and the radius and some of the carpals to form the wrist joint. The functions of the ulna include supporting movement of the extremities, creating insertion points for muscles, producing blood cells in bone marrow, and storing minerals.
Radius
The radius is a long bone that is located in the forearm. There is one radius in each arm, and they form a part of the appendicular skeleton. The radius articulates with the humerus and ulna to create the elbow joint and the ulna and some of the carpals to form the wrist joint. The functions of the radius include supporting movement of the extremities, creating insertion points for muscles, producing blood cells in bone marrow.