What are the ulna radius and humerus part of?

The ulna, radius, and humerus are all part of the upper limb (arm) of the human skeleton. The humerus is the single bone of the upper arm, extending from the shoulder joint to the elbow joint. The ulna and radius are the two bones of the forearm, with the ulna located on the medial (little finger) side and the radius on the lateral (thumb) side.