Inferior Aspect of the Anterior Segmental Bronchus Supplying the Left Lung

Description

Seen from the diaphragmatic (inferior) surface, the left lung is oriented with the cardiac impression and lingula positioned anteromedially and the oblique fissure sweeping posteroinferiorly toward the hilum. The left superior lobar bronchus is traced to its anterior segmental bronchus (B3, bronchus segmentalis anterior), which courses anteroinferiorly within the upper lobe to supply the anterior bronchopulmonary segment. Segmental branching is shown in relation to the medial and lateral margins of the lung base, helping separate B3 from adjacent segmental territories such as the apicoposterior segment (B1+2) and the lingular bronchi (B4 and B5). Clear topography. For bronchoscopy and thoracic surgery, segmental anatomy is the map, and B3 is a common landmark when planning a left upper lobe segmentectomy or when interpreting selective airway obstruction. A mucus plug or aspirated material lodged in the anterior segmental bronchus can produce focal atelectasis or postobstructive infection confined to the anterior segment, a distribution that makes more sense when you appreciate the bronchus’ anteroinferior course from an inferior viewpoint. This perspective also supports correlation with CT in the supine patient, where dependent changes and basal atelectasis can obscure fissural boundaries unless the segmental bronchial tree is kept in mind. Use this illustration in respiratory anatomy teaching blocks, bronchoscopy curricula, and surgical atlases covering bronchopulmonary segments, including preoperative planning discussions for VATS segmentectomy of the left upper lobe. It also fits radiology texts that annotate segmental bronchial anatomy for CT airway mapping and localization of endobronchial lesions. Anatomical accuracy verified by SciePro's Medical Advisory Board.