**Core Concept**
The **transverse pericardial sinus** is a critical anatomical structure located in the pericardial space, separating the great vessels into an anterior and posterior group. This sinus is significant for cardiac surgery. The **superior vena cava**, **ascending aorta**, and **main pulmonary artery** are anterior, while the **inferior aorta** and **superior** aspects of the heart are posterior to it.

**Why the Correct Answer is Right**
Given the options are missing, a general explanation is provided. Structures posterior to the transverse pericardial sinus typically include parts of the heart and major vessels that are not directly involved in the anterior great vessel group. The sinus itself allows for a plane of dissection that can be crucial in surgical procedures.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option provided, a general statement is made. Incorrect options would typically involve structures known to be anterior to the transverse pericardial sinus.
**Option B:** Similarly, without specifics, this option would be incorrect if it describes an anterior structure.
**Option C:** This would be incorrect if it describes a structure not posterior to the sinus.
**Option D:** Incorrect if not corresponding to known posterior structures.

**Clinical Pearl / High-Yield Fact**
A key point to remember is the location and relation of major cardiac structures to the transverse pericardial sinus, which is essential for understanding cardiac anatomy and performing cardiac surgeries.

**Correct Answer:** Correct Answer: C. Superior vena cava