Posterior segmental artery of right lung

The posterior segmental artery of the right lung (A2), is a segmental branch of the right pulmonary artery that supplies the posterior segment (S2) of the right upper lobe.

Origin and course: The right pulmonary artery first gives off a superior trunk known as the truncus anterior, which typically supplies the apical (A1) and anterior (A3) segmental arteries. The posterior segmental artery (A2) characteristically arises distal to the truncus anterior, either as a separate branch from the right pulmonary artery or from the interlobar artery (ascending posterior artery). It courses posteriorly to supply the posterior segment of the right upper lobe.

Anatomical significance:

• The posterior segment (S2) lies along the posterosuperior aspect of the right upper lobe, bordered superiorly by the apical segment (S1) and anteriorly by the anterior segment (S3).

• The A2 artery closely accompanies the posterior segmental bronchus (B2) and runs in proximity to the intersegmental veins that demarcate the boundaries between adjacent segments.

• Anatomical variants are common the A2 may arise as a single trunk, as duplicate branches, or may share a common origin with A1 (apicoposterior trunk). In some variant branching patterns (e.g., type-3 pattern), A2 may originate separately and directly from the mediastinal segment of the right pulmonary artery rather than from the interlobar artery.