Pulmonary ventilation movements are due to :

Options

A. Costal muscles
B. Diaphragm
C. Wall of lungs
D. Costal muscles and diaphragm

Answer

**Step-by-Step Solution:**

1. **Understanding Pulmonary Ventilation:**
- Pulmonary ventilation refers to the process of moving air in and out of the lungs, which is essential for gas exchange.

2. **Identifying the Muscles Involved:**
- The primary muscles involved in pulmonary ventilation are the diaphragm and the intercostal muscles (which include both internal and external intercostal muscles).

3. **Role of Intercostal Muscles:**
- The intercostal muscles are located between the ribs and are divided into:
- **External Intercostal Muscles:** These are responsible for forced inhalation by lifting the rib cage and expanding the thoracic cavity.
- **Internal Intercostal Muscles:** These are mainly involved in forced exhalation by pulling the rib cage down and reducing the thoracic cavity's volume.

4. **Role of the Diaphragm:**
- The diaphragm is the primary muscle of respiration. It contracts during inhalation, increasing the volume of the thoracic cavity, which allows air to flow into the lungs. During exhalation, it relaxes, decreasing the volume and pushing air out of the lungs.

5. **Evaluating Other Options:**
- The wall of the lungs does not actively participate in the movements of pulmonary ventilation, so it is not a correct answer.
- The term "costal muscles" is often used interchangeably with intercostal muscles, but it is important to note that the diaphragm is also crucial for ventilation.

6. **Conclusion:**
- The correct answer to the question is that pulmonary ventilation movements are due to both the diaphragm and the intercostal muscles.

**Final Answer:**
- The pulmonary ventilation movements are due to the diaphragm and intercostal muscles.

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