All the following are tributaries of Superior vena cava except
Right Brachiocephalic vein
Left Brachiocephalic vein
Hemiazygous vein
Azygous vein
Superior vena cava is a large venous channel which collects blood from the upper half of the body and drains it into the right atrium. It is formed by the union of the right and left brachiocephalic or innominate veins behind the lower border of the first right costal cailage close to the sternum. Each brachiocephalic vein is formed behind the corresponding sternoclavicular joint by the union of the internal jugular and subclan veins. Tributaries:1. The azygos vein arches over the root of the right lung and open into the superior vena cava at the level of the second costal cailage, just before thelatter enters the pericardium.2. Several small mediastinal and pericardial veins drain into the vena cava.Ref: BD Chaurasia; Volume 1; 6th edition; Page no: 258
Thorax