Left lower lobe bronchus
Lobar bronchi · 4 segments Anteromedial basal fused
Continuation of the left main bronchus after the upper lobe bronchus leaves it. It gives the superior segmental bronchus backwards, then anteromedial, lateral and posterior basal segmental bronchi; the medial and anterior basal bronchi usually share a common stem on the left.
Traced from the start
- Trachea
- Left main bronchus
- Left lower lobe bronchus
Detail
- Origin
- Posterolateral continuation of the left main bronchus beyond the upper lobe bronchus
- Branches
- Superior, anteromedial basal, lateral basal and posterior basal segmental bronchi
- Segment count
- Four, because the medial and anterior basal bronchi are fused; the left lung therefore has 8 segments in most texts against 10 on the right (9 or 10 if the fused pairs are counted separately)
When it goes wrong
Left lower lobe collapse
Triangular retrocardiac density (sail sign) with loss of the medial left hemidiaphragm; the commonest lobe to collapse after cardiac surgery
Aspiration while lying on the left side
Left lower lobe pneumonia in the superior or posterior basal segment; less common than the right because the bronchus is longer and more horizontal
Practise this structure
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