Left Lung, External Anatomy

Description

Positioned within the left hemithorax, the left lung is shown with its apex projecting superiorly toward the thoracic inlet and its base resting inferiorly on the diaphragm. Along the anterior border, the cardiac notch indents the upper lobe, with the lingula extending anteroinferiorly as a tongue-like projection. A single oblique fissure separates the superior lobe from the inferior lobe, running from a posterior, superior origin toward an anterior, inferior termination. The costal surface faces laterally toward the ribs, while the mediastinal surface lies medially, where the hilum would be located. Attention to the left lung’s external landmarks matters because they anchor bedside exam, imaging interpretation, and operative planning in the thorax. The cardiac notch explains why cardiac percussion and precordial auscultation encounter less overlying lung on the left, and it also frames the region where the lingula can mimic right middle lobe pathology on chest radiographs and CT when atelectasis or pneumonia is present. During thoracoscopic wedge resection or segment-oriented surgery, the oblique fissure guides access to the lower lobe and helps anticipate where incomplete fissures may complicate dissection and postoperative air leak. Faculty will find this plate useful for teaching respiratory gross anatomy in medical and allied health curricula, and for labeling exercises that contrast left and right lung lobation and anterior border contour. It also supports clinical education materials for radiology and pulmonary medicine that explain lingular syndromes, left-sided effusions, and how mediastinal impressions relate to surface anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.