Posterior Basal Segment of the Lung

Description

Posteriorly in the inferior lobe, the posterior basal bronchopulmonary segment (segmentum basale posterius, S10) occupies the most dependent portion of the lung base, lying inferior to the superior segment (S6) and posterior to the anteromedial basal segments. Its segmental bronchus and accompanying branch of the pulmonary artery course centrally within the segment, while the intersegmental pulmonary veins track along the connective tissue planes that separate S10 from adjacent basal segments. Laterally, the segment approaches the costal pleura, and inferiorly it rests against the diaphragmatic pleura at the extreme base. Boundaries are typically implied by the segmental anatomy rather than by gross fissures. Dependence matters. In the upright patient, aspirated material and secretions commonly gravitate to basal segments, and when the patient is supine the posterior basal segments become frequent repositories for aspiration pneumonia and dependent atelectasis. Segmental localization also guides interpretation of chest CT and bronchoscopy reports, where “posterior basal” opacities or bronchiectasis point you toward S10 and its segmental bronchus as the anatomic unit of disease. For thoracic surgeons, segmentectomy planning hinges on identifying the segmental bronchus (B10), artery (A10), and preserving the intersegmental veins that define the resection plane. Pulmonology and radiology curricula use this view to teach bronchopulmonary segments, gravity-dependent pathology, and the language of segmental reporting in CT, bronchoscopy, and operative notes. It also fits cleanly into atlases and publisher diagrams explaining lower-lobe segmentectomy and postoperative air leak patterns along intersegmental planes. Anatomical accuracy verified by SciePro's Medical Advisory Board.