Which muscle contracts during normal expiration?

Options

A. Diaphragm
B. EICM
C. IICM
D. None of these

Answer

To determine which muscle contracts during normal expiration, we can analyze the process of breathing and the roles of different muscles involved.

### Step-by-Step Solution:

1. **Understanding Expiration**:
- Expiration is the process of exhaling air from the lungs. It is generally a passive process during normal breathing.

2. **Muscles Involved in Breathing**:
- The primary muscles involved in breathing are the diaphragm and the intercostal muscles.
- The diaphragm contracts during inhalation (inspiration), while the intercostal muscles assist in both inhalation and exhalation.

3. **Normal Expiration**:
- During normal expiration, the diaphragm relaxes, and the elastic recoil of the lungs helps push air out.
- The intercostal muscles (specifically the internal intercostal muscles) may assist in forced expiration, but they are not primarily responsible for normal expiration.

4. **Analyzing the Options**:
- **Diprogram**: This seems to be a misspelling of "diaphragm," which contracts during inhalation, not expiration.
- **EICM (External Intercostal Muscles)**: These muscles assist in inhalation, not expiration.
- **IICM (Internal Intercostal Muscles)**: These muscles can assist in forced expiration but are not primarily responsible for normal expiration.
- **None of these**: This option suggests that none of the listed muscles are responsible for normal expiration.

5. **Conclusion**:
- Since normal expiration is primarily a passive process that does not require the contraction of any specific muscle, the correct answer is "none of these."

### Final Answer:
**None of these.**