Membranous partition between pericardial cavity and pleuropericardial cavity is

Options

A. Septum transversum
B. Mediastinal septum
C. Diaphragm
D. None of the above .

Answer

To determine the membranous partition between the pericardial cavity and the pleuropericardial cavity, we need to analyze the given options step by step:

### Step 1: Understand the Terms
- **Pericardial Cavity**: This is the space surrounding the heart, containing pericardial fluid that reduces friction during heartbeats.
- **Pleuropericardial Cavity**: This is the space that includes both the pleural cavities (surrounding the lungs) and the pericardial cavity.

### Step 2: Analyze the Options
1. **Septum Transversum**: This structure is primarily involved in embryonic development and contributes to the formation of the diaphragm. It does not serve as a partition between the pericardial and pleuropericardial cavities. Thus, this option is incorrect.

2. **Mediastinal Septum**: The term "mediastinal" refers to the central compartment of the thoracic cavity. The mediastinal septum acts as a partition between the pleuropericardial cavity and the pericardial cavity. This makes it a strong candidate for the correct answer.

3. **Diaphragm**: The diaphragm is a muscular structure that separates the thoracic cavity from the abdominal cavity. It does not function as a partition between the pericardial and pleuropericardial cavities. Therefore, this option is also incorrect.

4. **None of the Above**: Since we have identified the mediastinal septum as a valid option, this choice is not applicable.

### Step 3: Conclusion
Based on the analysis of the options, the correct answer to the question is:
**Mediastinal Septum (Option B)**