The most important muscular structure in respiratory system of human is

Options

A. External intercostal muscles
B. Internal intercostal muscles
C. Diaphgram
D. Vertebral column

Answer

**Step-by-Step Solution:**

1. **Understanding Respiration**:
- Respiration is the process of taking in oxygen from the atmosphere and expelling carbon dioxide from the lungs.

2. **Identifying Muscles Involved**:
- The main muscles involved in the process of respiration are the diaphragm and the intercostal muscles (both internal and external).

3. **Role of the Diaphragm**:
- The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. It plays a crucial role in the breathing process by contracting and relaxing.

4. **Inspiration Process**:
- During inspiration, the diaphragm contracts, which increases the volume of the thoracic cavity. This leads to a decrease in pressure inside the lungs (interpulmonary pressure), allowing air to flow in from the atmosphere.

5. **Expiration Process**:
- In expiration, the diaphragm relaxes, and the intercostal muscles also return to their original positions. This decreases the thoracic volume and increases the pressure in the lungs, causing air to be expelled.

6. **Conclusion**:
- Among the options provided (external intercostal muscles, internal intercostal muscles, diaphragm, vertebral column), the diaphragm is identified as the most important muscular structure in the respiratory system due to its primary role in driving the process of breathing.

**Final Answer**: The most important muscular structure in the respiratory system of humans is the **diaphragm** (Option 3).

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