Ventral surface(sternocostal surface) of hea is contributed by - 2/3rd of right ventricle (major contributor) 1/3rd of left ventricle Right atruim and left auricle. During embryological formation of the hea, the aerial and venous ends of the hea tube are fixed in place. As fuher growth continues, the hea tube folds to the right. This greatly contributes to the ventral surface of the adult hea being comprised primarily of the right ventricle.