There is typically a single bronchial vein at each hilum, formed from the superficial bronchial veins with deep bronchial veins draining into the pulmonary veins.
Deep bronchial veins
The deep bronchial veins form from intrabronchial venous plexuses, which unite to form venous trunks that run along the bronchi and near the hilum, uniting to form deep bronchial veins. These veins drain either directly into the left atrium or into the pulmonary vein. Within the lung, there are significant anastamoses with the intrapulmonary pulmonary veins.
Superficial bronchial veins
The superficial bronchial veins consist of a subpleural venous network which receives tributaries from extra-pulmonary bronchi, hilar lymph nodes and the vaso vasorum of the hilar pulmonary vessels and unite to form a single bronchial vein at each hilum.
On the right they drain into the azygos vein. On the left they drain into the left superior intercostal vein, accessory hemiazygos vein or left brachiocephalic vein. At the hilum there is communication with the pulmonary veins.