anterior interventricular sulcus aorta aortic sinus apex of the heart base of the heart bundle of his cardiac pacemaker cardiac skeleton circulatory system conus arteriosus cusps of heart valves diaphragmatic surface of heart endocardium fibrous pericardium fibrous rings of heart fibrous trigone gpnotebook heart heart valve human anatomy interatrial groove latin left atrial appendage left heart left margin of heart limbus of fossa ovalis musculi pectinati pericardial cavity pericardial sinus pericardium posterior interventricular sulcus public domain pulmonary artery pulmonary circulation purkinje fibers right atrial appendage right atrium right border of heart right heart suny downstate medical center serous pericardium sinoatrial node sinus venosus sternocostal surface systemic circulation torso trabeculae carneae university of michigan valve of the coronary sinus valve of the inferior vena cava