Ulna

At the elbow, identify three bones: the humerus, radius and ulna. The humerus approaches the elbow from above; the radius and ulna extend from the elbow towards the wrist, forming the forearm.

To distinguish the radius and ulna, imagine standing with your arms by your sides and your palms facing forwards. The radius is on the thumb side; the ulna is on the little-finger side. The l in ulna can remind you of little finger.