Medial Aspect of the Colored Apicoposterior Segment of the Left Lung

Description

Medially, the apicoposterior segment (segmentum apicoposterius, S1+S2) of the left upper lobe is isolated in color against the remainder of the lung, with its segmental bronchus and pulmonary arterial branch implied deep to the parenchyma. Its apex reaches superiorly toward the thoracic inlet, while the posterior component sweeps inferiorly and posteriorly along the upper thoracic wall. Along the medial surface, the segment abuts the mediastinum, sitting lateral to the superior mediastinal structures and superior to the oblique fissure that separates it from the superior segment of the lower lobe. Boundaries matter. This medial perspective is useful when you need to think in bronchopulmonary segments rather than lobes, such as planning a segmentectomy for a small peripheral non small cell lung carcinoma or discussing endobronchial localization for hemoptysis. On the left, S1 and S2 are commonly fused, so understanding the combined apicoposterior segment helps explain why wedge resection margins can be unpredictable and why segmental lymphatic drainage may track to hilar and superior mediastinal nodes. Surgeons and interventional pulmonologists often reference these planes when correlating bronchoscopy findings with CT. Use this plate for thoracic anatomy and respiratory system teaching, for surgical atlases illustrating left upper lobe segmentectomy, and for radiology education pairing color segment maps with axial and coronal CT bronchovascular anatomy. It also fits pathology and oncology publications that discuss segment based staging, resection planning, or targeted bronchoscopic sampling. Anatomical accuracy verified by SciePro's Medical Advisory Board.