The usual nerve susceptible to injury in mid humerus fractures is the radial nerve. Since the radial nerve passes near the middle as well as the lower part of the humerus, it is anatomically close to the humerus. When a mid humerus fracture occurs, it can lead to significant fracture displacement due to muscular pulling. When the fracture is displaced, it is particularly likely to crush the radial nerve immediately posterior to the humerus, and can even contuse the radial nerve, creating obvious symptoms of radial nerve injury. The radial nerve mainly innervates the forearm extensor muscles, which have the function of extending the wrist, lifting the thumb, stretching the fingers, etc. When the radial nerve is injured, it will cause numbness of the skin sensation on the radial side of the back of the hand. Therefore, the nerve that is easily damaged in mid humerus fracture is usually radial nerve, and it is usually necessary to do radial nerve exploration during surgery, and if there is a break in the nerve, the nerve should be repaired by surgery positively.