This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
Structure posterior to transverse pericardial sinus is 
Select and explain. 
A. Aoa, B. Pulmonary trunk, C. SVC, D. Left atrium
C: SVC
Answer: C: SVC 
Explanation: The transverse sinus is a horizontal gap between the aerial and venous ends of the hea tube.It is bounded anteriorly by the ascending aoa and pulmonary trunk,and posteriorly by the superior venacava and inferiorly by the left atrium on each side it opens into the general pericardial cavity. <img src=" /> REF.B D Chaurasia's human anatomy vol.1,fifth edition