Inferior accessory fissure of the lung

Dr Henry Knipe et al.

The inferior accessory fissure of the lung, also known as Twining's line, divides the medial basal bronchopulmonary segment from the rest of the lower lobe.

This accessory fissure occurs in 5-8% of frontal chest x-rays and is approximately five times more common on the right than the left. Commonly it is incomplete and may only extend for 0.5-2 cm 1.


Chest x-ray
Thoracic anatomy
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Article Information

rID: 22331
System: Chest
Section: Anatomy
Synonyms or Alternate Spellings:
  • Twining's line
  • Twining's lines
  • Inferior accessory fissure

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Cases and Figures

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    Case 1: inferior accessory fissure
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    Case 2: inferior accessory fissure
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    Case 3: right inferior accessory fissure
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    Sorry - bone wind...
    Case 4: right inferior accessory fissure
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    Case 5: Twining's line
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