Accessory fissures of the lung

Abstract

Accessory fissures of the lung are commonly observed in lung specimens, but are often unappreciated or misinterpreted in radiographs and computer tomographic (CT) scans. They usually occur at the boundaries between bronchopulmonary segments. Most common are the inferior accessory fissure, which demarcates the medial basal segment; the superior accessory fissure, which demarcates the superior segment; and the left minor fissure, which demarcates the lingula. This essay will illustrate the findings of the common accessory fissures both on plain radiographs and on CT scans.