The subclavius muscle is a relatively minor muscle located deep within the chest. The human body has two of these muscles, each inserting into the inferior of the clavicle bone (collarbone). The origination of each muscle is from the first rib. The muscles attach to each of the first ribs via costal cartilage – a fibrous, connective tissue high in collagen. During breathing, the costal cartilage allows the chest to expand and contract freely. Both of these muscles serve a simple purpose, which involves lifting the first ribs during respiration. The muscles also stabilize or hold the clavicle in place by drawing it in the direction of the sternum during pectoral movement. Each subclavius muscle has a nerve supply, which gives it its ability to perform its job within the body. In this case, it is the subclavian nerve. The origin of the subclavian nerve is C5 and C6, also known as cervical nerves five and six. The subclavian nerve junctions with the frontal region of the subclavian artery, connected by a phrenic nerve that contains sympathetic, sensory and motor nerve fibers.