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 of which organ or structure lacks innervation from the parasympathetic nervous system, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Innervation**: Innervation refers to the supply of nerves to a specific organ or structure. The autonomic nervous system is divided into two branches: the sympathetic and the parasympathetic.

2. **Analyze Each Option**:
- **Option 1: Iris Muscle**: The iris muscles are responsible for controlling the size of the pupil and are innervated by the parasympathetic nervous system. Therefore, this option does not lack parasympathetic innervation.

- **Option 2: Erector Pili Muscles**: These muscles are associated with hair follicles and are responsible for causing hair to stand on end (goosebumps). They are innervated by the sympathetic nervous system. Therefore, this option lacks innervation from the parasympathetic nervous system.

- **Option 3: Liver**: The liver receives innervation from the parasympathetic nervous system, primarily through the vagus nerve. Thus, this option does not lack parasympathetic innervation.

- **Option 4: Salivary Glands**: Salivary glands also receive innervation from the parasympathetic nervous system, which stimulates saliva production. Hence, this option does not lack parasympathetic innervation.

3. **Conclusion**: Based on the analysis, the only structure that lacks innervation from the parasympathetic nervous system is the **Erector Pili Muscles**.

### Final Answer:
The organ/structure that lacks innervation from the parasympathetic nervous system is the **Erector Pili Muscles**.

---