<prompt> Posterior to transverse pericardial sinus is:AoaPulmonary trunkSVCLeft atrium  <response>: Transverse pericardial sinus lies between the aoa and pulmonary trunk anteriorly and the superior vena cava posteriorly. Boundaries :- Below-left atrium Above - bifurcation of pulmonary trunk Behindposterior- superior vena cava In front- ascending aoa and pulmonary trunk Clinically, in cardiac surgery, temporary ligature or clamp is passed through transverse pericardial sinus to stop or dive the circulation of blood in large aeries . 