Lung fissures (anatomy)

The lung fissures are divisions from the surface to the hila of lung tissue which divide it into lobes. They include the:

• oblique fissures on both sides
• the horizontal fissure on the right

The oblique fissure divides the left lung into superior and inferior lobes. On the right, the oblique fissure demarcates along a similar route, but the presence of the horizontal fissure results in the following arrangement:

• superior lobe rests superior to oblique and horizontal fissures
• middle lobe rests superior to oblique fissure but inferior to horizontal fissures
• lower lobe rests inferior to oblique fissure

In a significant proportion of the population, the fissures are incomplete and the lobes merge. Conversely, a minority display accessory lobes due to the creation of new fissures e.g. the meso-azygous fissure.