Half of the hand numbness to exclude whether it is due to physiological reasons, may also be caused by pathological reasons, such as ulnar neuritis, carpal tunnel syndrome and so on. 1. Physiological causes: physiological numbness of half of the hand, commonly found in the palm of the elbow for a long time pressure to the elbow and other places, can cause poor local blood circulation, affecting the blood supply, there can be numbness of the hand phenomenon, such as poor posture in the process of sleep, pressure to the palm or arm for a long time. 2. ulnar neuritis: ulnar neuritis can appear in the numbness of the little finger and ring finger, as well as the numbness of the ulnar side of the palm of the hand in the area of the small fish margin. As the ulnar nerve undergoes an inflammatory reaction, its edema and friction within the axial canal can cause symptoms of nerve damage. 3. Carpal tunnel syndrome: Carpal tunnel syndrome can be caused by the compression of the median nerve in the carpal tunnel, which can result in the three and a half fingers on the radial side of the numbness, tingling or weakness and other syndromes. In addition, the cause of hand numbness of the pathology of the cause is more, it is recommended to go to the hospital for examination, in order to clarify the cause of the disease, can be the cause of treatment.