Each of the tertiary bronchi serves a specific bronchopulmonary segment. These segments each have their own artery. Thus, each bronchopulmonary segment is supplied by a segmental bronchus, and two arteries, a pulmonary artery and a bronchial artery which run together through the center of the segment. Veins and lymphatics drain along the edges.
There are 10 bronchopulmonary segments in the right lung (3 in superior lobe, 2 in middle lobe, 5 in inferior lobe) and 9 segments on the left (4 in upper lobe, 5 in lower lobe).
Note : there are some variation in the nomenclature and numbers of lobes, for example, in the lower lobe of left lungs, some authors merge the anterior and medial basal segments, with only 4 segments in this lobe.