I would like to clarify my understanding because anatomy atlases do not provide me an explanation. As far as I know, the aortic bulbus is a part (the widest, the sinuses of Valsalva) of the aortic root. But browsing through some medical reports, I can see these are often reported individually, e.g. Ascending Aorta (X mm), Aortic Root (Y mm), Aortic Bulbus (Z mm). As the bulbus should be part of the root, what is the "root" exactly referring to?