The tangent of the main influencing angle is an important parameter for mining subsidence prediction and surface displacement range demarcation .

主要影响角正切是开采沉陷预计的重要参数，对于 地表影响范围的 确定具有重要的意义。

Conclusion : Through separating anterior apex notch middle accessory fissure and basal-anterior accessory fissure could be shown and those intersegmental planes are the surface landmarks of bronchopulmonary segmental demarcation line and approaches of segmentectomy of lung .

结论：尖前切迹、中副裂、底前副裂能分离出段间平面，是肺段 分界 的 表面标志，可作为肺段切除术的手术入路。