The sternoclavicular joint or sternoclavicular articulation is the joint between the manubrium of the sternum and the clavicle bone. It is structurally classed as a synovial saddle joint and functionally classed as a diarthrosis and multiaxial joint. It is composed of two portions separated by an articular disc of fibrocartilage. The bone areas entering into its formation are the sternal end of the clavicle, the upper and lateral part of the sternum, (the clavicular notch), and the cartilage of the first rib, visible from the outside as the suprasternal notch. The articular surface of the clavicle is much larger than that of the sternum, and is invested with a layer of cartilage, which is considerably thicker than that on the sternum.