Superior accessory fissure

The superior accessory fissure is present in around 5% of individuals examined with CT 4

The superior accessory fissure of the right lobe of the lung is located in the same plane and posterior to the right minor fissure. It separates the right lower lobe into superior and basal segments. This superior segment is called the posterior or dorsal lobe.

The fissure varies in length from complete to incomplete fissure 1,2. The incidence is greater with right lung involvement and less common than an inferior accessory fissure 1.

Plain radiograph

Frontal chest radiographs demonstrate a thin horizontal linear opacity projecting below, parallel, and medial to the right minor fissure. Lateral radiograph demonstrates thin line posterior to the right minor fissure, usually in the same plane and in a horizontal or oblique orientation. It may look like a continuation of the right minor fissure posteriorly, which separates right lower lobe into superior and inferior segments 1,2

Consider:

  • pleural-parenchymal scarring 
Thoracic anatomy
Chest x-ray
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Article information

rID: 26525
System: Chest
Section: Anatomy
Synonyms or Alternate Spellings:
  • Superior accessory fissures

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