There are 10 tertiary bronchi in the right lung serving corresponding segments of lung. On the left, the apical and posterior segments of the upper lobe come off a common bronchus as do the anterior and medial basal segments, resulting in only 8 tertiary bronchi.
The right upper lobe has anterior, posterior and apical segments. Right middle has lateral and medial segments. The right lower lobe has a superior segment and anterior, posterior, medial and lateral basal segments. The left upper lobe consists of apical-posterior, anterior and lingular segments. The lingula is divided into a superior and inferior segment. The left lower lobe has a superior segment, an antero-medial basal, posterior and lateral basal segments.
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