Which of the following parts of brain constitute the brain stem ?

Options

A. Midbrain and hindbrain
B. Hindbrain and forebrain
C. Forebrain and midbrain
D. Forebrain only

Answer

To determine which parts of the brain constitute the brain stem, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Nervous System**:
- The nervous system is divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and spinal cord, while the PNS consists of all the nerves branching off from the spinal cord.

2. **Identify the Components of the Brain**:
- The brain is further divided into several parts, including the forebrain, midbrain, and hindbrain. Each of these regions has specific functions and structures.

3. **Define the Brain Stem**:
- The brain stem is a crucial part of the brain that connects the cerebrum (the largest part of the brain) to the spinal cord. It plays a vital role in relaying information between these two regions.

4. **List the Parts of the Brain Stem**:
- The brain stem consists of three main components:
- **Midbrain**: The upper part of the brain stem, involved in vision, hearing, motor control, and alertness.
- **Pons**: Located below the midbrain, it acts as a bridge between different parts of the nervous system and plays a role in regulating breathing.
- **Medulla Oblongata**: The lowest part of the brain stem, it controls vital functions such as heart rate, blood pressure, and breathing.

5. **Conclusion**:
- Based on the above information, the parts of the brain that constitute the brain stem are the **midbrain**, **pons**, and **medulla oblongata**.

### Final Answer:
The brain stem is constituted by the **midbrain**, **pons**, and **medulla oblongata**.

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