Bone · Elbow

Ulna

Ulna

The ulna is the little-finger side bone of the forearm, and it is the stable one of the pair — the radius rotates around it, not the other way about. Its upper end wraps the end of the arm bone in a deep C-shaped notch to make the elbow hinge, and the point of that wrap, the olecranon, is the tip of your elbow. It is thick at the elbow and tapers to almost nothing at the wrist, barely reaching the joint.