This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Posterior wall of the structure pierced by the Index finger is 
Select and explain. 
A. Aortic arch, B. Azygos vein, C. Pulmonary veins, D. Superior Venacava
D: Superior Venacava
Answer: D: Superior Venacava 
Explanation: The structure pierced by Index finger is Transverse sinus. The posterior wall of Transverse sinus is Superior Venacava.