The ulna is located on the inside of the forearm. The ulna is one of the two long bones of the forearm, the other long bone being the radius. The ulna, like the other long bones, is divided into one body with two ends divided into three parts: the upper end, the lower end, and the body. The upper end of the ulna is thick and has a semilunar articular surface, also known as the semilunar notch or as the glide notch, which is articulated with the humeral glide. The body of the ulna is an important part of the ulna and is connected to the upper end of the ulna and the lower end of the ulna; the lower end of the ulna includes the styloid process, the ulnar eminence, and other structures. The ulna is easy to fracture, patients should avoid strenuous forearm exercise, ulna fracture timely medical treatment to avoid the development of the disease.