Right superior intercostal vein drains into:

Ans: B (Azygos vein) Ref: Gray's Anatomy, 39th edition, 2008, Page 966Explanation:Right second, third and sometimes fourth posterior intercostal veins unite to form superior intercostal veinRight superior intercostal vein joins with azygos veinTo remember:Left superior intercostal vein formed by the union of second, third and sometimes fourth left posterior intercostal veinsLeft superior intercostal vein open into left brachiocephalic vein.Azygos vein:Formed by union of right ascending lumbar vein and right subcostal vein opposite to LI or L2 vertebraEnters the thorax by passing through aortic opening of diaphragmAt the level of T4 arches over the root of right lung and opens into extra pericardial part of superior vena cavaTributaries of azygos vein:Right superior intercostal vein5'ih to 1101 right posterior intercostal veinsHemiazygos veinAccessory hemiazygos veinOesophageal veinsPericardial veinsRight bronchial veins