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

Explanation

To answer the question "Which of the following parts of the brain constitute the brain stem?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Brain Structure**: The brain is divided into several parts, including the cerebrum, cerebellum, and brain stem. The brain stem is crucial for regulating vital functions.

2. **Identify the Components of the Brain Stem**: The brain stem is primarily made up of three parts:
- **Midbrain**: The uppermost part of the brain stem, involved in vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation.
- **Pons**: Located below the midbrain, it acts as a bridge between different parts of the nervous system, including the cerebellum and the cerebrum. It plays a role in regulating breathing and communication between different parts of the brain.
- **Medulla Oblongata**: The lowest part of the brain stem, it controls autonomic functions such as breathing, heart rate, and blood pressure.

3. **Conclusion**: Based on the identification of these components, we can conclude that the brain stem consists of the midbrain, pons, and medulla oblongata.

4. **Final Answer**: Therefore, the correct answer to the question is that the brain stem is constituted by the midbrain, pons, and medulla oblongata.