Figure 6. Station 6. (A) The upper border of station 6 is a line tangential to the upper border of the aortic arch and lower border is the lower border of aortic arch (green lines). (B) The anterior border of station 6 is the imaginary horizontal line extending from the anterior wall of the aortic arch (yellow line), which discriminates station 6 from station 3a. AoA: aortic arch.