Which of the following organs / structures lacks innervation from parasympathetic nervous system?

Options

A. Iris muscles
B. Arrector pili muscles
C. Liver
D. Salivary glands

Answer

To solve the question "Which of the following organs/structures lacks innervation from the parasympathetic nervous system?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which organ or structure does not receive nerve supply from the parasympathetic nervous system. The parasympathetic nervous system is responsible for rest-and-digest functions and innervates various organs.

2. **Evaluate the First Option - Erector Muscles**:
- Erector muscles, specifically referring to the muscles that control the movement of hair follicles (erector pili muscles), are primarily innervated by the sympathetic nervous system.
- **Conclusion**: Erector pili muscles lack innervation from the parasympathetic nervous system.

3. **Evaluate the Second Option - Erector Pili Muscles**:
- As stated above, these muscles do not receive parasympathetic innervation. They are controlled by sympathetic fibers.
- **Conclusion**: This option is correct as they lack parasympathetic innervation.

4. **Evaluate the Third Option - Liver**:
- The liver is innervated by both the sympathetic and parasympathetic nervous systems. The parasympathetic innervation comes from the vagus nerve.
- **Conclusion**: The liver does not lack parasympathetic innervation.

5. **Evaluate the Fourth Option - Salivary Glands**:
- Salivary glands receive innervation from both the sympathetic and parasympathetic nervous systems. The parasympathetic innervation is primarily through the facial nerve (VII) and glossopharyngeal nerve (IX).
- **Conclusion**: Salivary glands do not lack parasympathetic innervation.

6. **Final Conclusion**:
- Based on the evaluations, the only structure that lacks innervation from the parasympathetic nervous system is the **Erector Pili Muscles**.

### Answer:
The correct answer is **Erector Pili Muscles**.