What major muscle causes frowning, smiling, pouting, and squinting?

Explanation

To answer the question about the major muscle responsible for frowning, smiling, pouting, and squinting, we can break it down step by step:

### Step-by-Step Solution:

1. **Identify the Actions**: The question asks about four specific facial expressions: frowning, smiling, pouting, and squinting.

2. **Muscles Involved in Frowning and Pouting**:
- The **corrugator supercilii** and **procerus muscles** are primarily responsible for frowning and pouting.
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