Inferior border of heart The inferior border of the heart, which is nearly horizontal, is primarily formed by the right ventricle.
Left border of the heart The left heart border describes the visible outline of the heart, including the curves formed by the aortic arch, pulmonary trunk, and left auricle, as well as the border of the left ventricle and the apex of the heart.
Right border of heart Right border of heart is represented by the vena cava superiorly and mainly by the right atrium inferiorly