Middle lobar artery of right lung

The right middle lobar artery of right lung arises from the right interlobar artery and supplies the lateral (S4) and medial (S5) segments. In approximately one-half of individuals, A4 and A5 arise as separate branches from the anteromedial aspect of the interlobar artery, and in the other one-half of individuals they arise as a common trunk at this location before dividing. 

Branches of right middle lobar artery:

• Medial segmental artery of right lung (A4)

• Lateral segmental artery of right lung (A5)