left auricle |  chordae tendineae from the tricuspid valve | right ventricle, with its papillary muscles projecting |  left ventricle with  papillary muscle | Note the much thicker wall on the left than on the right | pulmonary semilunar valve at the entrance to the pulmonary trunk |  left auricle |  left pulmonary veins |  ascending aorta |  superior vena cava | You can just barely make out the aortic semilunar valve in the shadow at the top of the left atrium.