Colored Medial Basal Segments of the Lungs, Inferior View

Description

Seen from an inferior, posterior-leaning perspective, the medial basal bronchopulmonary segments (segmentum basale mediale, S7) are isolated in color on the diaphragmatic and mediastinal aspects of the lower lobes. Each S7 lies inferomedially, bordering the pulmonary ligament and abutting the vertebral side of the mediastinum, with its segmental bronchus and accompanying segmental pulmonary artery branch running centrally and the intersegmental pulmonary veins marking the planes laterally. Posteriorly it relates to the posterior basal segment (S10), while anterolaterally it transitions toward the anterior basal segment (S8) where the diaphragmatic surface begins to broaden. This angle matters because S7 is a frequent point of confusion in segmental anatomy: it is variably developed, sometimes fused with S8, and its boundaries are easiest to conceptualize when you think in terms of the bronchovascular pedicle rather than surface fissures. For bronchoscopy and segmental resection planning, the inferomedial position explains why secretions and aspiration-related infection can track into basal segments in dependent patients, and why lymphatic drainage from the lower lobe can present with subcarinal or inferior pulmonary ligament node involvement. Small, but clinically stubborn. Use this illustration for teaching bronchopulmonary segment mapping in gross anatomy, respiratory medicine, and thoracic surgery modules, or as a figure in atlases and papers discussing VATS segmentectomy of the lower lobe and segmental anatomy on CT with multiplanar reconstructions. Anatomical accuracy verified by SciePro's Medical Advisory Board.