The applied anatomy and clinical significance of the proximal , V 1 segment of vertebral artery Short title : The V 1 segment of a sample of Chinese cadavers

Background: The aim of the study was to probe the morphological features of the proximal segment (V1) of vertebral artery (VA) in a sample of Chinese cadavers. Materials and methods: The origin, course and outer diameter at origin of the prevertebral part of the VAs were evaluated in 119 adult cadavers. Results: 94.12% of the VAs originated from the subclavian arteries, bilaterally. The variant origins were present in 5.88% of the cadavers and all originated directly from the arch of the aorta. All the variations were observed on the left side of male cadavers. The average outer diameters at origin of the normal and variation groups were 4.35 ±1.00 mm and 4.82 ±1.42 mm, respectively P=0.035). In the normal group, no variation group, the average diameter in the males was significantly larger than that in the females (4.50 ±0.99mm, 3.92 ±0.92mm), respectively, P=0.000. In addition, only 5 cadavers in the normal had hypoplastic VAs (4.20%, 4 males, 3 right sided). VAD was present in 91 (69 males) out of 112 cadavers and more common on the left (n=48). In addition, 3 cadavers satisfied conditions for coexistence of VAD and VAH. All 7 cadavers in the variations group exhibited VAD that was more common on the right side (n=5). Conclusions: The morphologic variations and frequencies described above have implications for the early prevention, abnormal anatomy detection, accurate diagnosis, safe surgery and endovascular treatment on cardiovascular and neurological disease.