Some standard anatomical descriptions of the cervical part of the vertebral artery mention little of its tortuosities. This study investigated the vertebral artery and its course using vertebral angiograms (37 sides) and preserved human cadaver injection studies (47 sides). In the Townes' projection of the former, the artery was seen consistently to pass laterally at the level of cervical vertebra 2 (C2), then to curve medially and then laterally as it climbed to enter the C1 foramen transversarium (F. T.). Analysis of dissection material and lateral angiograms revealed a tight posterior loop in the artery between C1 and C2. A “tortuosity variable” was calculated and was found to be positively correlated with age, but no relationship was found between tortuosity and the side of the body or the sex of the patient.
Analysis of radiographs of injected cadaver heads showed the posterior loop between C1 and C2 in 96% of cases; the region with the greatest variability in pathway was the C1/ C2 region, but tortuosity was also seen at a more caudal level in some cases.
As the tortuosity between C1 and C2 was also seen in young subjects (7 years old and older), reasons for its presence other than atherosclerosis are discussed. It is proposed that it may provide slack in the artery that is taken up on turning the head in order to avoid compromise to the cerebral circulation. © 1994 Wiley-Liss, Inc.