Posterior Perspective of the Colored Lateral Basal Segments of the Lungs

Description

Colored segmental anatomy of the lower lobes is presented with emphasis on the lateral basal bronchopulmonary segment (Segmentum basale laterale, S9) on each side. Positioned on the inferolateral aspect of the lung, S9 wraps onto the costal surface and sits inferior to the superior (apical) segment of the lower lobe (S6) and posterior to the anterior basal segment (S8), while remaining lateral to the medial basal segment (S7, when present on the right). The oblique fissure forms the superior boundary between lower lobe basal segments and the upper lobe, and the diaphragmatic surface curves medially and inferiorly beneath the basal pyramid. Segment-level orientation matters when you are correlating imaging and interventions at the lung base. S9 commonly abuts the posterolateral pleura and adjacent ribs, which explains why subpleural opacities, contusions, or peripheral pneumonias in this distribution can localize pain to the lateral chest wall and why thoracentesis and pleural biopsy trajectories must respect the nearby intercostal neurovascular bundle. On CT, dependent atelectasis and aspiration-related changes often favor the lower lobe bases, and distinguishing S9 from S10 helps map disease to a bronchopulmonary unit that can be approached with segmentectomy. Use this artwork in thoracic anatomy teaching (bronchopulmonary segments and fissures), radiology primers on lobar and segmental localization, and surgical or pulmonary publications discussing VATS segmentectomy planning at the lower lobe base and peripheral pleural-based lesions. Anatomical accuracy verified by SciePro's Medical Advisory Board.