The part of the ulna that is called elbow is olecranon.
The ulna extends through the forearm from the elbow to the wrist, narrowing towards the distal end (towards hand). At the proximal end, it forms the elbow joint with the humerus of the upper arm and the radius of the forearm. The ulna extends past the humerus to form the tip of the elbow, known as olecranon