The basilar bronchial trunk usually separates in two branches: B⁸ and B⁹⁺¹⁰ which lie posterior to the segmental arteries (◘ Fig. 19.1a).

The basilar arterial trunk branches in most cases in two arteries: A⁸ and A⁹⁺¹⁰. But all arteries to the lower lobe must be clearly identified in order to avoid misidentification, such as a low A^8a being mistaken for an A⁹⁺¹⁰ (see below). When in doubt during dissection, it is preferable to control only the anterior branch of A⁸ (A^8b), then the bronchus, and eventually check the direction of the second branch (◘ Fig. 19.1b).

The superior basal vein (SBV), which is the middle root of the IPV, does not always represent the venous drainage of segment 8. Its posterior branch can drain segment 9. It is advisable to divide only the anterior branch of the vein (V^8a) which runs immediately behind the bronchus, rather than controlling V⁸ centrally in the inferior pulmonary vein (◘ Fig. 19.1c).