Answer to Nightmare Before Christmas

Correct answer is B. The indicated structure is the coronary sinus, characterized by its presence in the atrioventricular sulcus.  The atrioventricular sulcus is identified because the valve to the left is the mitral valve and the left atrium is posterior (in the anatomical position). Hence, the left ventricle must be anterior. Anterior cardiac veins  drain directly to the right atrium, as does the SVC. Right and left pulmonary veins drain directly to the left atrium. This is a classic example of a gross anatomy  question, asking you to identify a structure, but the stem throws a curve ball to get the student to think in a different direction. Realize that whether the patient has congestive heart failure or not, the answer is the same.

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Answer to this question is based on material presented in lectures 10 of the Thorax Lecture Series.