Superior lingular segmental bronchus of left lung
Bronchus segmentalis lingularis superior pulmonis sinistri
- Latin synonym: Bronchus IV pulmonis sinistri
- Synonym: Bronchus 4 of left lung; B4
- Related terms: Superior lingular bronchus [B IV]
Definition
The superior lingular segmental bronchus (B4) is the branch of the lingular division bronchus that supplies the superior lingular segment (S4) of the left upper lobe of the lung.
Anatomical definition and relationships:
The left upper lobe bronchus divides into two main divisions: the superior division (supplying the apicoposterior and anterior segments) and the lingular division bronchus. The lingular division bronchus then typically bifurcates into two segmental bronchi:
B4 (superior lingular segmental bronchus) supplies the superior lingular segment
B5 (inferior lingular segmental bronchus) supplies the inferior lingular segment
The superior lingular segment (S4) lies anterosuperiorly along the left cardiac border, while the inferior lingular segment (S5) lies inferiorly. The lingula of the left lung is considered the anatomical homologue of the right middle lobe.
The most common pattern is a simple vertical bifurcation of the lingular bronchus into B4 and B5, observed in approximately 91-96.5% of individuals. Less common variants include:
A trifurcation pattern (B4, B5, and an accessory branch B), seen in approximately 9% of cases.
A rare horizontal bifurcation into lateral and medial lingular bronchi rather than superior and inferior, with an incidence of approximately 0.6%
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