The ulna is one of the two long bones in the forearm, the other being the radius. It is located on the side opposite the thumb and runs parallel to the radius. The ulna is slightly longer than the radius and plays a crucial role in forming the elbow joint, allowing for the bending and straightening of the arm. At its upper end, the ulna connects with the humerus, the bone of the upper arm, while at its lower end, it connects with the wrist bones. The ulna also provides support and stability to the forearm, making it essential for various movements, such as lifting and pushing.