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Figure 3a.  Tracheal bronchus. (a) Drawing shows the most frequent origin of the tracheal bronchus (arrows). (b) CT section demonstrates a right-upper-lobe bronchus (arrows) arising from the trachea, above the carina. (c) CT scan of the same patient at the level of the carina, 2 cm below the origin of the tracheal bronchus. (d) Bronchogram helps confirm the diagnosis and shows the origin of the tracheal bronchus. Rib alterations in the right hemithorax are secondary to prior thoracotomy.