The left and right bronchus are divided into lobar bronchus, the lobar bronchus and the segmental bronchus,Each lung segment has a corresponding lung segmental bronchus, whose name is roughly the same as the lung segment.(1) Right bronchus1. The upper lobe bronchus is divided into 1, 2 apical branches, 3 anterior branches and 3 posterior branches2. Middle lobe bronchus: divided into 4, medial 5, lateral branches3. Lower lobar bronchus: divided into 6, 7, 8, 9, 10 and 10 branches(2) Left bronchus1. Upper lobe bronchus: divided into 1, apical branch 2, anterior branch 3, superior lingual branch 4, inferior lingual branchLower lobar bronchus: it is divided into 5 branches, 6 upper branches, 7 anterior basal branches, 8 lateral basal branches and 8 posterior basal branches4、 Hilum: it shows the adjacent relationship between the left and right pulmonary vessels and bronchi