Posterior Basal Segments of the Left Lung, Medial View

Description

Oriented from the medial aspect of the left lung, the posterior basal segment (segmentum basale posterius, S10) occupies the inferoposterior portion of the inferior lobe, deep to the visceral pleura and immediately superior to the diaphragmatic surface. Its segmental boundaries relate to the oblique fissure anterosuperiorly, while the posterior margin of the lung lies lateral to the mediastinal surface that faces the pericardium and descending thoracic aorta. Segmental bronchi and accompanying pulmonary arterial branches run centrally toward the hilum, with pulmonary veins tracking more intersegmentally along the connective tissue septa. Segmental anatomy matters here because S10 is a frequent locus for dependent atelectasis and aspiration-related consolidation when a patient is supine, and it is commonly targeted in bronchoscopy, segmental lavage, and segmentectomy planning. A medial perspective clarifies why posterior basal disease can sit adjacent to the descending aorta and esophagus on cross-sectional imaging, and why pleural effusions can obscure the diaphragmatic contour without directly involving the bronchovascular core. Small errors in segment identification change operative margins. Fast. Use this asset in thoracic surgery teaching for left lower lobe segmentectomy (S6 versus S10 differentiation), in radiology atlases correlating bronchopulmonary segments with CT anatomy, and in pulmonary medicine materials covering aspiration patterns and postural drainage positioning. Anatomical accuracy verified by SciePro's Medical Advisory Board.