Anterior segmental bronchus of left lung

Latin synonym: Bronchus III pulmonis sinistri
Synonym: Bronchus 3 of left lung; B3
Related terms: Anterior segmental bronchus [B III]

Bronchus segmentalis anterior pulmonis sinistri

Antoine Micheau

The anterior segmental bronchus of the left lung (B3) is the segmental bronchus that arises from the left upper lobe bronchus (specifically the upper division bronchus) and ventilates the anterior segment (S3) of the left upper lobe.

Anatomical details:

The left upper lobe bronchus typically divides into an upper division and a lingular division. The upper division further branches into the apicoposterior segmental bronchus (B1+2) and the anterior segmental bronchus (B3).
The most common branching pattern (~76% of cases) is a bifurcation into B1+2 and B3. Less commonly (~17%), all three segments arise as a trifurcation (B1+2+3), and in ~6% of cases, B1+3 shares a common stem with B2 arising separately.