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 about which muscles are not involved in normal inspiration, normal expiration, and forceful inspiration, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify which muscle(s) are not involved in normal inspiration, normal expiration, and forceful inspiration.

2. **Identify the Options**: The question provides several muscle options. We will analyze each muscle's role in respiration.

3. **Analyze Each Muscle**:
- **Internal Intercostal Muscles**: These muscles are primarily involved in forceful expiration (exhalation) and are not used during normal inspiration or expiration. Therefore, they fit the criteria of the question.
- **External Intercostal Muscles**: These muscles are involved in normal inspiration and expiration. They help elevate the ribs during inhalation, making them essential for normal breathing.
- **Diaphragm**: The diaphragm is the primary muscle for normal inspiration and also plays a role in expiration. It contracts and flattens during inhalation, allowing air to fill the lungs.

4. **Determine the Correct Answer**: Since the internal intercostal muscles are not involved in normal inspiration and expiration, they are the correct answer to the question.

5. **Final Answer**: The muscles that are not involved in normal inspiration, normal expiration, and forceful inspiration are the **Internal Intercostal Muscles**.