AN ANALYSIS OF THE BRONCHOVASCULAR PATTERN OF THE LEFT LOWER LOBE IN FIFTY LUNGS OF THE CHINESE / 解剖学报

ABSTRACT

The distribution and arrangement of the segmental bronchi and blood vessels of the left lower lobe have been studied in fifty Chinese adult cadavers by the same methods as we did in the other four lobes.The bronchus of the left lower lobe usually divided into four segmental bronchi,namely the apical (B~6), the antero-medial basal (B~(7+8)), lateral basal (B~9), and the posterior basal (B~(10)). Occasionally, an extra one, the subapical bronchus (B~*), has been identified in 14% of the specimens in this series.The prevailing pattern (48%) of the branching of the apical bronchus is a bifurcation having the formula "B~6b, B~6a+c". The basal trunk bronchus frequently divides into two stems--commonly B~(7+8) and B~(9+10) (60%). The status of the medial basal bronchus in the left lower lobe has been discussed.Same reason as we have discussed in the bronchial pattern of the right lower lobe, the BX~*(9) and BX~*(10) of the lower lobe should be considered as a posterior ramus of B~9 and B~(10) respectively. The posterior ramus of the lateral basal bronchus (B~9c) has been found in 64% of the specimens, and that of the posterior basal (B~(10)c) in 88%. The distributive extents of the basal segmental bronchus of the left lower lobe, seems to present a tendency of more or less counterclockwise rotation, in contrast with the right lower lobe.In one-fourth of thespecimens, the mode of the branching of the basal artery ismuch more complicated than that of the basal ronchus. The prevailing pattern of thebranches of the apical segmental artery corresponds to the bronchial pattern having theformula "A~6b, A~6a+c" (30%). Similar to the basal trunk, A~(7+8) and A~(9+10) are the chiefpatterns (34%) of the branching of the basal artery. The subapical arteries (A~*) arefound in 14%; it may originate from the lateral basal artery (6%) or the posteriorbasal artery of the superior ramus of the anterior-basal subsegmental artery. Of specialinterest are the two specimens in which A~(10) is displaced upward and arises in commonwith A~6. Such an arrangement is clinically significant.The veins of the left lower lobe coincide with those of the other four lobes, mostof them are located between segments or subsegments. The venous pattern of the leftlower lobe resembles that of the right lower lobe, the left pulmonary vein received V~6and the common basal vein. The common basal veins receives two main tributaries, thesuperior and the inferior basal vein. The former is commonly formed by V~(7+8)a+V~9 and the latter by V~(10). Such instance is present in 36% of the specimens.