The clavicle is the long bone that runs between your shoulders and breastbone, and it's commonly known as the collar bone. Because it's a bone, you can't stretch the clavicle itself. However, the area around the clavicle is a common starting point for tension and soreness, and stretching the muscles surrounding the clavicle can help reduce muscular tension in your upper body, according to the book "Stretching Anatomy."
The platysma, a long muscle in the neck, originates at the clavicle, and sometimes pain around the clavicle is caused by tension in the neck. Other muscles in the neck that can cause clavicle pain include the scalenus muscles and the sternocleidomastoideus. People who sit at a desk all day looking down at a computer are likely to experience neck tension, but regular stretching can relieve this problem. One way to do this is to sit or stand with your shoulders straight, then move your neck to each side, as if you're trying to touch your shoulder with your ear. Repeat on each side five to 10 times. After that, roll your neck in a clockwise motion, then a counterclockwise motion.
The collar bone is connected to the pectoral muscles of the chest, and stretching your chest muscles can help alleviate tension around the collar bone. One method of stretching this area starts with you standing or sitting up straight. From this position, bend your elbows in each arm, and move your arms toward your back. Get as close to touching your elbows together as you can until you feel a stretch, then hold that position five seconds and repeat five times. Also, you can stand in a doorway and position one arm in front of the door while leaning into the door with your elbow bent. Turn your body away from that arm until you feel a stretch. Repeat the movement on the other side. A hunched posture tends to tighten muscles around the chest, so focusing on keeping your shoulders back and torso upright while working or reading can make a difference.
Your clavicle is connected to the scapula -- the large bone in the back of the shoulder -- so loosening the muscles in your shoulders, particularly the trapezius and scapulae, can help reduce tension in much of your upper body. One way to stretch those muscles is to stand about two feet from a wall, and move your arm backward over your head. Rotate your hand so that it faces the wall, then rest your hand against the wall until you feel a stretch. Repeat with the other hand. Then grab the elbow of your right arm with your left hand and push your elbow across your chest until you feel a stretch. Repeat with your left hand.
Upper Back Stretch
Your back stabilizes your body and commonly harbors tension. It also connects to your clavicle via your shoulder blades. A strong back can help you maintain a healthy posture, which can help prevent muscle strain. Upper back muscles you can stretch include the latissimus dorsi and rhomboids. One method to stretch these muscles is to put your hands behind your head, then move your elbows backward until you feel a stretch. Repeat three or four times.