<prompt> Right heart border is formed by-Superior vena cavaSuperior vena cava right atriumSuperior vena cava right atrium inferior vena cavaRight ventricle  <response>: Ans. is c i.e., Superior vena cava right atrium inferior vena cava o In PA view the right margin of heart is formed by superior vena cava, right atrium and inferior vena cava from above downward. The left margin is formed by aortic knuckle Prominence due to arch of aorta, Pulmonary trunk, left auricle and left ventricle from above downward.o Right heart border is mainly formed by right atrium,o Left heart border is mainly formed by left ventricle.o Anterior border of heart is formed by from above downwards : i Ascending aorta; ii Pulmonary artery; and ill Right ventricleo Posterior border of heart is formed by from above downwards : i Pulmonary artery; ii Left atrium; and iii Left ventricle. 