This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2018, Subject name: Anatomy
Left superior intercostal vein drains into ? 
Select and explain. 
A. Azygous vein, B. Hemiazygous vein, C. Brachiocephalic vein, D. Internal thoracic vein
C: Brachiocephalic vein
Answer: C: Brachiocephalic vein 
Explanation: 2,3,4-posterior intercostal vein on left side drains into left superior intercostal which fuher drains into left brachiochephalic vein . Right and left brachiocephalic veins joins to form superior vena cava that opens into right atrium Posterior Intercostal Veins and their drainage: Right side drains into 1stposterior intercostal vein Right brachiocephalic vein 2,3,4 posterior intercostal vein Arch of azygos vein 5 to 11 posterior intercostal vein Azygos vein Left side drains into 1stposterior intercostal vein Left brachiocephalic vein 2,3,4-posterior intercostal vein Left brachiocephalic vein 5,6,7 posterior intercostal vein Superior hemiazygous vein 8,9,10 posterior intercostal vein Inferior hemiazygous vein