Question
The SA node is situated at the junction of:
| A. |
SVC and RA |
| B. |
SVC and LA |
| C. |
LA and LV |
| D. |
IVC and RA |
Show Answer
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Correct Answer � A Explanation |
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The Sinoatrial (SA) node, often called the “pacemaker” of the heart, is anatomically located at the junction of the superior vena cava (SVC) and the right atrium (RA). This specialized cluster of cells generates electrical impulses that initiate the heartbeat and set the heart rate.
Key Points About the SA Node:
-
Location:
- The SA node is situated in the upper part of the right atrium, near the opening of the superior vena cava.
-
Function:
- It initiates electrical impulses that spread through the atria, causing their contraction.
- The intrinsic rate of the SA node is typically 60–100 beats per minute in adults.
-
Blood Supply:
- The SA node is usually supplied by the right coronary artery (in 60% of individuals) or the circumflex artery (in 40%).
Reasons to Rule Out Other Options:
B. SVC and LA:
- The left atrium (LA) is not connected to the superior vena cava. Hence, the SA node cannot be located here.
C. LA and LV:
- This junction represents the left atrioventricular region, unrelated to the SA node, which is on the right side of the heart.
D. IVC and RA:
- The inferior vena cava (IVC) connects to the lower part of the right atrium, but the SA node is located at the superior aspect of the right atrium near the SVC opening.
