Anatomical relationships between the V₂ segment of the vertebral artery and the cervical nerve roots

Object. During surgical procedures focused on the cervical nerve roots, the surgeon works in proximity to the V₂ segment of the vertebral artery (VA). Depending on the specific surgical approach, it may be necessary to identify, expose, or mobilize the artery. In most cases, the artery may be left undisturbed. To reduce the risk of iatrogenic injury to the V₂ segment during anterior and anterolateral approaches to the cervical spine, the authors analyzed the relationship between the V₂ segment and the proximal segment of the C3-6 nerve roots. Methods. Six cadaveric cervical spines (12 sides) were fixed with formalin, injected with red and blue latex, and investigated intraoperatively using different magnifications (X 3-40). The VA rested on the anteromedial surface of the cervical nerve roots at the level of each intertransverse space. The exiting nerve roots intersected the VA at a distance ranging from 4.5 to 8.1 mm (mean 6.3 ± 1.06 mm) from the dural sac. The distance was slightly shorter at cephalad levels, suggesting that the artery is more posteriorly and medially situated at those levels. Arterial pedicles anchored the VA to the cervical nerve roots at various levels. These arteries gave rise to purely radicular, ligamentous, and medullary branches without a predictable pattern. After reaching the nerve roots on their lower margin, the nonligamentous branches pierced the radicular dural sheath within the neural foramen at a distance of 2 to 4 mm from the VA. Conclusions. Proximal-to-distal dissection of a cervical nerve root may proceed with relative safety for at least 4 mm. The V₂ segment of the VA gives rise to at least one radicular arterial pedicle between C-4 and C-6. These trunks give rise to purely radicular, ligamentous, and medullary branches in an unpredictable pattern.