The tulang ulna, or ulna bone, is one of the two long bones in the forearm, the other being the radius. It is located on the inner side of the forearm, opposite the thumb. The ulna is longer than the radius and plays a crucial role in forming the elbow joint, connecting with the humerus at the upper end and the wrist bones at the lower end. The ulna has a distinctive shape, featuring a prominent bony projection called the olecranon, which forms the tip of the elbow. This bone helps in the movement of the arm and provides stability during various activities, such as lifting and pushing.