Left superior lobar bronchus

The left superior lobar bronchus (Left upper lobe bronchus) is the airway branch that arises from the left main bronchus and supplies the left upper lobe of the lung. It is one of two lobar bronchi on the left side (the other being the left inferior lobar bronchus, which supplies the left lower lobe), reflecting the bilobar anatomy of the left lung.

Key anatomical features:

• Origin: It branches from the left main bronchus after the carina. The left main bronchus is characteristically longer and more horizontal than the right before giving off the left superior lobar bronchus.

• Divisions: The left superior lobar bronchus typically divides into two major divisions:

  • The superior division (or upper division), which further branches into the apicoposterior segmental bronchus (B1+2) and the anterior segmental bronchus (B3).

  • The lingular division, which gives rise to the superior lingular (B4) and inferior lingular (B5) segmental bronchi.

• Branching patterns: The most common pattern of the superior division is a common stem of the apical and posterior segmental bronchi (B1+2) with a separate anterior segmental bronchus (B3), seen in approximately 64-76% of individuals. Other patterns include trifurcation of B1, B2, and B3 (~17-23%) and a common stem of B1+3 with a separate B2 (~6-10%).