①Understanding the normal findings based on the anatomy of the trachea and bronchi, as well as their branching patterns and nomenclature, is necessary to perform bronchoscopy. ②Understanding the layered structure of the bronchial wall is particularly important and is the basis for detecting and deciphering abnormal findings. In the 2018 revision of the classification of bronchoscopic findings according to the Japan Society for Bronchology, changes to the endoscopic terminology used for different layers of the bronchial wall were introduced, and this publication has been drafted accordingly. Knowledge of the normal trachea and bronchi images is needed in order to perform high-quality bronchoscopy. Furthermore, an accurate analysis of the findings obtained can only be achieved by understanding the site (segmental anatomy) and histological structure (structural anatomy) that is being observed under bronchoscopy. In the 2018 revision of the classification of bronchoscopic findings according to the Japan Society for Bronchology, the words "mucosal" and "submucosal" were no longer used as endoscopic terms referring to different layers of the bronchial wall. Instead, the terms "epithelial", "subepithelial", and "intramural" were used in order to ensure consistency with anatomical terminology. Understanding the peripheral bronchial bifurcations is important for improving the accuracy of biopsies of the bronchi involved in peripheral lung nodules, as this facilitates the correct insertion of the bronchoscope. Ultrafine bronchoscopes can reach more-peripheral bronchi than standard-size bronchoscopes; therefore, understanding the branching of peripheral bronchi is more important than ever.
