Which of the following help to increase the volume of the thoracic chamber during the mechanism of breathing?
(a) The contraction of diaphragm
(b) Contraction of external intercostal muscle
(c) The uplifting of sternum
(d) All of the above

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, "Which of the following help to increase the volume of the thoracic chamber during the mechanism of breathing?" we need to analyze each option provided:

1. **Understanding the Mechanism of Breathing**:
- Breathing involves two main processes: inspiration (inhaling) and expiration (exhaling). During inspiration, the volume of the thoracic cavity increases, allowing air to flow into the lungs.

2. **Analyzing Each Option**:
- **(a) The contraction of 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 is a key mechanism in inspiration.

- **(b) Contraction of external intercostal muscle**: 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. This also plays a significant role in the process of inspiration.

- **(c) The uplifting of sternum**: The sternum, or breastbone, can also be lifted during inspiration. This action is often associated with the movement of the ribs and contributes to the expansion of the thoracic cavity.

- **(d) All of the above**: Since all the above actions (contraction of diaphragm, contraction of external intercostal muscles, and uplifting of sternum) contribute to increasing the volume of the thoracic chamber during inspiration, this option suggests that all mechanisms are involved.

3. **Conclusion**:
- Since all three mechanisms (diaphragm contraction, external intercostal muscle contraction, and uplifting of the sternum) help to increase the volume of the thoracic chamber during breathing, the correct answer is **(d) All of the above**.