which of these muscles are not involved in normal inspection, normal expiration as well as forceful inspiration ?

Options

A. Internal intercostal muscles
B. External intercostal muscles
C. Diaphragm
D. All three of these muscles

Answer

To solve the question of which muscle is not involved in normal inspiration, normal expiration, and forceful inspiration, we can analyze the functions of the given muscles:

1. **Internal Intercostal Muscles**:
- These muscles are primarily involved in forceful expiration. They help to depress the ribs and push air out of the lungs during activities like coughing or heavy breathing.
- They are not involved in normal inspiration or normal expiration, which primarily rely on other muscles.

2. **External Intercostal Muscles**:
- These muscles are responsible for normal inspiration. They elevate the ribs and expand the thoracic cavity, allowing air to flow into the lungs.
- They also assist in normal expiration but are not responsible for forceful expiration.

3. **Diaphragm**:
- The diaphragm is the primary muscle used in normal inspiration. It contracts and moves downward, increasing the volume of the thoracic cavity and drawing air into the lungs.
- It also plays a role in normal expiration but is not involved in forceful expiration.

4. **Conclusion**:
- Since the question asks for the muscle that is not involved in normal inspiration, normal expiration, and forceful inspiration, the **Internal Intercostal Muscles** are the correct answer.

**Final Answer**: The muscle that is not involved in normal inspiration, normal expiration, and forceful inspiration is the **Internal Intercostal Muscle**.