Inferior Lobe of the Left Lung Viewed in Medial Orientation

Description

Medial orientation of the left lung’s inferior lobe brings the diaphragmatic (basal) surface and its segmental anatomy into clear relief, with emphasis on the lateral basal bronchopulmonary segment (segmentum basale laterale, S9). From this inner aspect, the segment lies in the inferolateral portion of the lower lobe, abutting the costal surface laterally and the diaphragmatic surface inferiorly while remaining posterior to the lingula. The medial surface contours toward the cardiac impression anteriorly and the posterior mediastinum posteriorly, with the hilum and pulmonary ligament region providing proximal landmarks for segmental relationships. Segment-level understanding matters. Left lower-lobe pneumonias, atelectasis, and bronchiectasis often localize to the basal segments, and bronchoscopy, segmentectomy, or VATS wedge planning depends on anticipating where S9 sits relative to the oblique fissure and the mediastinal pleura. Radiologists also lean on this mental map when correlating a posterolateral basal opacity on CT with the expected airway and vascular territories, distinguishing a true segmental process from pleural-based disease. Use this artwork in thoracic anatomy teaching when you want learners to stop thinking in lobes alone and start thinking in bronchopulmonary segments, including segmental bronchi and their paired arterial supply. It also fits surgical atlases, pulmonary and critical care slide decks, and patient-facing materials explaining why a lesion in the left lower lobe may require a targeted, parenchyma-sparing resection. Anatomical accuracy verified by SciePro's Medical Advisory Board.