This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
All of the following drain into azygous vein, except 
Select and explain. 
A. Left superior intercostals, B. Accessory hemiazygous, C. 5 to 11 posterior intercostals on Rt side, D. Esophageal veins
A: Left superior intercostals
Answer: A: Left superior intercostals 
Explanation: Accessory hemiazygous vein drain at the level of upper border of 8th thoracic veebra. 5th to 11th right posterior intercostal veins are tributaries of azygos vein. Left superior intercostal veins are tributaries of hemizygous and accessory hemiazygous vein. B D Chaurasia 7th edition Page no: 233