Unstriated muscles in the vertebrates are also called

Options

A. Cardiac muscles
B. Skeletal muscles
C. Tonal muscles
D. Visceral or smooth muscles

Answer

**Step-by-Step Solution:**

1. **Understanding Muscle Types**: Begin by recognizing that there are three main types of muscles in vertebrates: cardiac muscle, skeletal muscle, and smooth muscle.

2. **Defining Striated and Unstriated Muscles**:
- Striated muscles have visible light and dark bands (striations) due to the arrangement of actin and myosin filaments. Examples include cardiac and skeletal muscles.
- Unstriated muscles do not have these striations and appear smooth.

3. **Identifying Unstriated Muscles**: Among the three types of muscles, only smooth muscle is classified as unstriated. It is characterized by:
- A spindle shape.
- A single nucleus per cell.
- The absence of striations.

4. **Eliminating Incorrect Options**:
- Cardiac muscle is striated.
- Skeletal muscle is also striated.
- The term "tonal muscle" is not recognized in the classification of muscle types.

5. **Conclusion**: Based on the characteristics of unstriated muscles, the correct answer to the question is that unstriated muscles in vertebrates are called **visceral or smooth muscles**.

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