Colored Lateral Basal Segment of the Left Lung, Medial View

Description

Oriented in a medial perspective from the midline, the left lung is presented with the inferior lobe emphasized, isolating the lateral basal segment (segmentum basale laterale, S9) in color against adjacent parenchyma. The highlighted territory lies inferolateral within the lower lobe, bounded superiorly by the superior segment (S6) and anteromedially by the anteromedial basal region (often described as S7 plus S8 or a merged anteromedial basal segment on the left, depending on the scheme). Along the medial surface, the segment relates to the mediastinal pleura near the inferior pulmonary ligament and sits inferior to the hilar structures where the left main bronchus and pulmonary artery enter the lung root. Segmental anatomy matters in the left lower lobe because S9 commonly participates in dependent atelectasis and aspiration-related consolidation, yet its bronchovascular supply can be preserved or sacrificed selectively during sublobar resection. Surgeons plan a left lower-lobe segmentectomy by tracing the segmental bronchus (B9) and segmental artery (A9) at the hilum, then dividing along the intersegmental plane that separates S9 from S6 and the adjacent basal segments. One wrong plane leaves a persistent air leak. Use this illustration for thoracic surgery teaching on segmentectomy planning, pulmonary segment nomenclature in gross anatomy and radiology curricula, and figure panels in manuscripts discussing lower-lobe pneumonia distribution, bronchopulmonary segment variations, or VATS/robotic approaches to S9. Anatomical accuracy verified by SciePro's Medical Advisory Board.