Triangular muscle weakness can develop from different causes, mainly due to temporary or long-term injury to the fifth nerve root in the cervical spine. Since the muscles around the shoulder become stiff and painful because of the decreased motion around the shoulder joint, it is important to perform functional movement exercises. The following describes in detail the functional exercises that should be performed 3 times a day. 1. Lie flat on your back, use your strong forearm, hold the back side of the weak elbow joint, lift it towards your head and hold it for 5 seconds, then place the weak limb on the side of your body. Repeat 10 times. 2. Sitting on a stool shorter than a hard bed, bend forward while keeping your back straight and allow your shoulder joints to gently rotate as you bend. Hold the position for 5 seconds, then return to the starting position. Repeat 10 times. 3. Grasp the ends of the towel or rope as shown below (the right upper limb is the weak limb). Lift the right upper limb as far as possible, but do not overstretch it. Maintain the position for 5 seconds, then then return to the starting position. Repeat 10 times. 4. Grasp the ends of the rope through a pulley or similar device, straighten your weak limb, pull the rope up as high as possible through your strong arm, maintain the position for 5 seconds, and gently return to the original position. Repeat 10 times. 5. Grasp a stable object, such as a doorknob, with the hand of the weak limb and bend the affected elbow 90°. Rotate the trunk as far as possible to the opposite side, maintain the position for 5 seconds, and then gently return to the starting position. Repeat 10 times. 6. In the standing position, grasp the elbow joint of the arm on the weak side with the hand on the strong side and try to move it across the chest wall to the opposite side, maintaining the position for 5 seconds, then return to the starting position. Repeat 10 times. 7, standing position, grab a stick with both hands and hold it palm down. Lift both upper limbs so that your elbows are straight, maintain for 5 seconds, then return to the starting position. Repeat 10 times. 8, standing position, holding a short stick with both hands behind you, keep your elbow joints straight position will be short stick off your back. Maintain the position for 5 seconds, then return to the starting position. Repeat 10 times. 9, supine position, holding a short stick in both hands, elbow joints are 90 ° flexed position on both sides of the body, palms up. Then use your strong side of the upper limb to push the weak side of the upper limb off the body surface as much as possible. Maintain the extended position for 5 seconds and then return to the original resting position of the elbow joint. Repeat 10 times. 10. In a standing position, hold a short stick with both hands behind you, leaning with the stick behind you and bending the elbow joint as far as possible. Maintain the position for 5 seconds, then return to the starting position and repeat 10 times. 11.Standing position, holding a short stick in front of your body with both hands, palms down, short stick in front of your thighs, elbow joints straight. Use the strong side of the upper limb to push the weak side of the upper limb to the weak side, as high as possible. Hold the position for 5 seconds, then return to the starting position. Repeat 10 times. 12. In the standing position, shrug your shoulders upward and hold for 5 seconds. Then push your shoulder blades backward with the upward motion and hold for 5 seconds. Then, push your shoulder blades downward again and hold for 5 seconds. Rest. Repeat the process 10 times. 13: Stand at the corner of a doorway or room, raise your hands as high as you can on the door frame or wall with your hands above your head and lean forward slowly until you feel a stretch in your shoulders, hold the position for 15 to 30 seconds. Then return to the starting position and repeat 3 times.