In this unit, you have learnt that heart is a muscular organ situated in thorax covering with pericardium and consist of four chambers i.e. right atrium, left atrium, right ventricle and left ventricle. These atrium and ventricles are separated by interatrial septum and interventricular septum respectively. Left atrium and left ventricle as well as right atrium and right ventricle are connected with atrioventricular orifices where Mitral valve and tricuspid valve are situated respectively.  Heart has its own special conduction system.  It also has coronary arteries for its blood supply. The border of the heart as well as valve of the heart can also be identified by surface marking of the heart.