**Question:** Atrial myxoma commonly arises from-

A. Right atrium
B. Left atrium
C. Aortic valve
D. Mitral valve

**Core Concept:** Atrial myxomas are benign tumors that can develop within the heart, particularly in the atria. They are classified as primary cardiac tumors, meaning they arise from the heart itself, rather than spreading from elsewhere within the body.

**Why the Correct Answer is Right:** Atrial myxomas are primarily found in the atria, with a higher prevalence in the left atrium. This is due to the fact that the left atrium has a larger surface area and receives a higher volume of blood, providing a more favorable environment for tumor formation.

**Why Each Wrong Option is Incorrect:**

A. Right atrium: The right atrium receives deoxygenated blood from the body and oxygenated blood from the lungs, making it less suitable for tumor formation.
B. Left atrium: As explained above, the left atrium has a larger surface area and receives a higher volume of blood, making it the correct choice.
C. Aortic valve: Atrial myxomas do not arise from the valvular structures, but within the heart muscle itself.
D. Mitral valve: Like option C, atrial myxomas do not develop from valvular structures, but rather from the heart muscle.

**Clinical Pearl:** Atrial myxomas are a rare but important differential diagnosis when assessing a patient presenting with embolic events (e.g., stroke) or systemic embolization. A thorough clinical examination, imaging studies, and echocardiography can help diagnose these tumors.

**Correct Answer:** B. Left atrium