Anterior basal segmental bronchus of left lung

The anterior basal segmental bronchus of the left lung (B8) is the bronchus that supplies the anterior basal segment (S8) of the left lower lobe. It arises from the left basal trunk (the common basal bronchus) after the superior segmental bronchus (B6) has branched off, and it courses anteriorly and inferiorly to ventilate the anterior portion of the basal pyramid of the left lower lobe.

Anatomical details:

• The left lower lobe bronchus first gives off the superior segmental bronchus (B6), and the remaining trunk is termed the basal bronchus. This basal bronchus then divides into the individual basal segmental bronchi: the anteromedial basal (B7+8), lateral basal (B9), and posterior basal (B10) bronchi.

• In the left lung, the anterior basal (B8) and medial basal (B7) bronchi frequently share a common stem (B7+8), unlike the right lung where B7 and B8 are typically separate. This is because the heart occupies the space where a distinct medial basal segment would otherwise exist on the left side.

• The predominant branching pattern of the left basal bronchi is a bifurcation pattern (approximately 75% of individuals), where the basal trunk divides into an anteromedial trunk (B7+8) and a posterolateral trunk (B9+10). A trifurcation pattern (approximately 18%) is the next most common variant.

• The anterior basal segment (S8) that B8 supplies is located on the anterior and inferior surface of the left lower lobe, bordered by the lateral basal segment laterally and the medial basal segment medially.