The common clinical reasons for not being able to lift the hand high enough to straighten it include carpal tunnel syndrome, radial nerve injury, vascular nerve compression in the arm area, and joint stiffness. 1. Carpal tunnel syndrome: this disease refers to a peripheral nerve compression syndrome caused by the compression of the median nerve in the carpal tunnel, with clinical manifestations such as numbness and weakness of the hand and pain in the anterior part of the wrist, which is common among cooks, programmers, carpenters, etc., who need to exert force on the wrist for a long period of time. 2. Radial nerve injury: this disease is usually associated with trauma to the body, such as electrical burns, traction injuries, radiation injuries, gunshot wounds, etc., and its typical clinical symptoms include weakening or loss of wrist extension, finger extension and abnormal sensation of the dorsal side of the tiger’s mouth. 3. Arm part of the blood vessels and nerves are compressed: when part of the population lying on their stomachs to sleep or sleeping on their sides, the arm part of the nerves and blood vessels may be compressed, resulting in numbness, pain, weakness and other symptoms of the arm. This is a physiological change, appropriate relaxation of the arm and adjust the sleeping position can be. 4. Joint stiffness: clinically common diseases that cause such symptoms are arthritis, joint adhesion, etc., the sick people’s joints are prone to inflammatory exudation, resulting in swelling, stiffness and discomfort. If the above situation exists, it is recommended to consult a doctor for a clear diagnosis and targeted treatment if the situation is serious.