Muscles with characteristic striations and involuntary are

Options

A. muscles in the wall of alimentary canal
B. muscles of the heart
C. muscles assisting locomotion
D. muscles of the eyelids

Explanation

To answer the question "Muscles with characteristic striations and involuntary are," we need to analyze the types of muscles in the human body.

### Step-by-Step Solution:

1. **Identify Muscle Types**: There are three main types of muscles in the human body: skeletal muscles, cardiac muscles, and smooth muscles.

2. **Understand Striations**:
- **Striated Muscles**: These muscles have a banded appearance due to the arrangement of myofibrils. Skeletal and cardiac muscles are striated.
- **Non-Striated Muscles**: Smooth muscles do not have this banded appearance.

3. **Determine Involuntary vs. Voluntary**:
- **Involuntary Muscles**: These muscles function without conscious control. Cardiac and smooth muscles are involuntary.
- **Voluntary Muscles**: These muscles are under conscious control, such as skeletal muscles.

4. **Analyze Cardiac Muscles**:
- Cardiac muscles are found in the heart. They are striated and involuntary, meaning they have the characteristic striations and operate without conscious control.

5. **Analyze Smooth Muscles**:
- Smooth muscles are found in the walls of hollow organs (like the intestines) and are involuntary but do not have striations.

6. **Analyze Skeletal Muscles**:
- Skeletal muscles are striated but are voluntary, meaning they are under conscious control.

7. **Conclusion**: Based on the characteristics of striations and involuntary nature, the correct answer is cardiac muscles.

### Final Answer:
The muscles with characteristic striations and involuntary nature are **cardiac muscles**.

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