Right inferior lobar bronchus

The right inferior lobar bronchus (Right lower lobe bronchus; RLLB) is the airway that arises from the bronchus intermedius after the right middle lobe bronchus branches off, and it supplies the right lower lobe of the lung.

• The right main bronchus divides into the right upper lobe bronchus and the bronchus intermedius. The bronchus intermedius then gives rise to the right middle lobe bronchus anteriorly, and continues as the right inferior lobar bronchus posteriorly.

• The right inferior lobar bronchus further divides into segmental bronchi that supply the five segments of the right lower lobe. In the most common branching pattern, these are:

  • B6 - superior (apical) segmental bronchus of the lower lobe

  • B7 - medial basal segmental bronchus

  • B8 - anterior basal segmental bronchus

  • B9 - lateral basal segmental bronchus

  • B10 - posterior basal segmental bronchus

Anatomical variations are common. The most frequent pattern (approximately 57% of cases) is the classic five-branch configuration (B6, B7, B8, B9, B10), but variants include absence of a separate B9, fusion of B8+9, or trifurcation patterns.