Right ventricle The right ventricle forms the anterior (sternocostal) surface of the heart. So, this is the surface of the heart that lies against the sternum and would be injured following a crushing blow to the sternum. There are 2 other surfaces of the heart of which you should be aware. The diaphragmatic surface of the heart is formed by the left ventricle, with a little bit of the right ventricle. This is the surface of the heart which is in contact with the diaphragm. The pulmonary surface of the heart is on the left side of the heart. It is mostly formed by the left ventricle.