One of the following lies in the wall of right auricle

Options

A. Purkinje fibres
B. Bundle of HIS
C. SA node
D. Chordae tendinae

Answer

To determine which structure lies in the wall of the right auricle, we will analyze the options provided and identify the correct answer step by step.

### Step 1: Understanding the Right Auricle
The right auricle (or right atrium) is one of the four chambers of the heart. It receives deoxygenated blood from the body through the superior and inferior vena cavae.

### Step 2: Analyzing the Options
We need to evaluate the options provided to see which one is located in the wall of the right auricle.

1. **Purkinje Fibers**: These are specialized fibers that are part of the heart's conduction system. They are primarily found in the ventricular walls and are responsible for conducting electrical impulses to the ventricular muscles. Therefore, they do not lie in the wall of the right auricle.

2. **Bundle of His**: This structure is also part of the heart's conduction system and is located in the interventricular septum. Its main function is to transmit electrical impulses from the atrioventricular (AV) node to the ventricles. Thus, it is not located in the wall of the right auricle.

3. **SA Node (Sinoatrial Node)**: The SA node is known as the natural pacemaker of the heart. It is located in the upper wall of the right atrium (auricle) and is responsible for initiating the electrical impulses that regulate heartbeats. This is the correct answer.

4. **Chordae Tendineae**: These are fibrous cords that connect the papillary muscles to the tricuspid valve and mitral valve in the heart. They help in the functioning of the heart valves but are not located in the wall of the right auricle.

### Conclusion
Based on the analysis, the correct answer is the **SA Node**, as it is the only structure listed that is found in the wall of the right auricle.

### Final Answer
**The structure that lies in the wall of the right auricle is the SA Node.**

---