Observation of the Oblique Fissure of the Left Lung, Medial View

Description

Seen from the medial aspect of the left lung, the oblique fissure (fissura obliqua) runs as a long interlobar cleft separating the superior lobe anteriorly and superiorly from the inferior lobe posteriorly and inferiorly. Its course sweeps inferoanteriorly toward the diaphragmatic surface, creating the major division between lobes without crossing the hilum. Medial visceral pleura borders the fissure margins, with the fissural lips forming the interface where lobar surfaces appose. Clear appreciation of the oblique fissure matters when you need to localize lobar disease on imaging and when planning procedures that track along interlobar planes. Lower lobe pneumonias and atelectasis can silhouette along this fissure on chest radiographs, and pleural effusions may layer to mimic fissural thickening or a pseudotumor within an interlobar septum. For thoracic surgeons, the fissure dictates the dissection plane during left upper lobectomy or left lower lobectomy, and a partially fused (incomplete) fissure increases air leak risk during fissure division. Fissure anatomy is not optional. Use this illustration for gross anatomy and respiratory system teaching, radiology correlation figures that compare medial lung morphology to lateral chest views, and operative atlases discussing fissure-based approaches in VATS lobectomy. It also suits educational content on lobar localization of bronchopulmonary pathology and interlobar pleural disease. Anatomical accuracy verified by SciePro's Medical Advisory Board.