The part below the clavicle is the thorax, which consists of the thoracic vertebrae, ribs, sternum, and the muscles, skin, and soft tissues attached to the surface that make up the thorax. Inside the thorax are two important organs, the lungs and the heart, which are responsible for the body’s breathing and the orderly circulation of blood. Between the thorax and the clavicle, that is, below the middle part of the clavicle, there are also important vascular nerves passing through, the brachial plexus nerve and the subclavian artery. The brachial plexus nerve emits five major branches, the musculocutaneous, axillary, median, ulnar and radial nerves, which are responsible for the movement and sensation of the upper extremities, shoulders, elbows, wrists and fingers, and the subclavian artery, which supplies blood circulation to the upper extremities.