The sternum is formed by three bones; the manubrium, the sternal body and the xiphoid process (xiphisternum). These bones articulate together by hyaline cartilage with a fibro-cartilaginous disc to form the anterior and midline portion of the chest wall.
The has many articulations, where the manubrium articulates with the first rib and the clavicle while the sternal body articulates with the second to seventh ribs as well as the costal cartilages.
This 3D model was created from the file STS_044. The source CT scan used to create this model can be found here.