Which of the following help to increase the volume of the thoracic chamber during the mechanism of berating ?

Options

A. The contraction of diaphragm the
B. Contraction of exteranal intercostal muscle
C. The up lifting of sternum
D. All of the above

Answer

To solve the question regarding which mechanisms increase the volume of the thoracic chamber during breathing, we can analyze each option provided:

### Step-by-Step Solution:

1. **Understanding the Mechanism of Breathing**:
- Breathing involves the expansion and contraction of the thoracic cavity, which allows air to flow in and out of the lungs.

2. **Analyzing the First Option - Contraction of the Diaphragm**:
- The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. When it contracts, it flattens and moves downward, increasing the volume of the thoracic cavity. This allows the lungs to expand and fill with air.
- **Conclusion**: This option is correct.

3. **Analyzing the Second Option - Contraction of External Intercostal Muscles**:
- The external intercostal muscles are located between the ribs. When these muscles contract, they lift the rib cage upward and outward, further increasing the volume of the thoracic cavity.
- **Conclusion**: This option is also correct.

4. **Analyzing the Third Option - Uplifting of the Sternum**:
- The sternum, or breastbone, is connected to the ribs. During inhalation, as the external intercostal muscles contract, the sternum is also lifted, contributing to the increase in the thoracic cavity's volume.
- **Conclusion**: This option is correct as well.

5. **Final Conclusion**:
- Since all three mechanisms (contraction of the diaphragm, contraction of external intercostal muscles, and uplifting of the sternum) contribute to increasing the volume of the thoracic chamber during breathing, the correct answer is **All of the above**.

### Final Answer:
**All of the above (Option D)**

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