USMLE High-Yield Questions on Instagram: "“Apex → axilla = the beat leaking backwards.” ⸻ ✅ Answer & Explanation Correct answer: B) Mitral regurgitation A holosystolic murmur best heard at the apex with radiation to the axilla is the classic auscultation finding of mitral regurgitation. Blood flows backward from the left ventricle into the left atrium throughout systole, and the sound tracks laterally toward the axilla. This is one of the most reliable murmur location → diagnosis pairings on USM