Lung fissures

Last revised by Liz Silverstone on 12 Mar 2023

Lung fissures are double-folds of visceral pleura that either completely or incompletely invaginate lung parenchyma to form the lung lobes. 

Each lung has an oblique fissure separating the upper lobes from the lower lobes and the right lung has a horizontal fissure that separates the right upper lobe from the middle lobe

There are numerous accessory fissures that are common anatomical variants


Oblique fissure (also known as major fissure) is similar for both lungs. It extends from the level of T4/T5 vertebrae posterosuperiorly to the hemidiaphragms anteroinferiorly and is gently undulating in nature. The left oblique fissure has a more vertical course compared to the right oblique fissure 2.

A transverse fissure (also known as a minor fissure) is only found in the right lung. It separates the upper and middle lobes of the right lung. The transverse fissure runs horizontally at the level of right fourth costal cartilage from the hilum to the anterior and lateral surfaces of the right lung. The fissure is complete in only one-third of the subjects and is absent in 10% of the subjects 2.

See also

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Cases and figures

  • Figure 1
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  • Case 1: normal appearance on chest CT
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