“…Most of the documented measurements of VA blood flow were made at several different levels (Figure 1), such as the pretransverse (first) part of the VA (VA1: Licht, Christensen, Hojgaard, and Hoilund-Carlsen, 1998a;Licht, Christensen, Hojgaard, and Marving, 1998b;Licht, Christensen, and Hoilund-Carlisen, 1999; the cervical vertebral level (second part) (VA2: Refshauge, 1994;Thiel, Wallace, Donat, and Yong-Hing, 1994;Haynes, 1996Haynes, , 2000Rivett, Milburn, and Chapple, 1998;Haynes, Hart, and McGeachie, 2000;Haynes and , 2001;Zaina et al, 2003;Arnold, Bourassa, Langer, and Stoneham, 2004), and in the region of the axis (VA2: Stevens, 1991;Refshauge, 1994;Haynes, 1996Haynes, , 2000Rivett, Milburn, and Chapple, 1998;Haynes, Hart, andMcGeachie, 2000, Haynes andMilne, 2001). No studies of the suboccipital (third) part of the VA (VA3) are reported in the current literature.…”