Surgical anatomy and quantitation of the branches of the V2 and V3 segments of the vertebral artery Laboratory investigation

Object. The vertebral artery (VA) and its branches may be encountered during various neurosurgical procedures such as far lateral suboccipital approaches to the skull base and spinal operations. Therefore, a working knowledge of the distribution and significance Of Such VA branches may be advantageous to the surgeon. To date, quantitation of these branches is lacking in the literature. Methods. The authors evaluated the branches of 20 VAs from 10 adult cadavers and assessed the distribution and surgical significance of the branches from the V-2 and V-3 segments. Results. In terms of target tissues, the VA branches encountered at the C1-2 level were most likely to be muscular, branches at C2-3 osseous, and those at C3-6 radicular. No radicular or medullary branches were identified arising from any V-3 segment of the VA or C1-2 level of the V-2 segment. The greatest concentration of branches per level was found arising from the V-2 segment at C2-3. Posterior branches of the VA tended to be radicular or muscular, whereas anterior branches tended to be radicular or osseous. Lateral branches were most commonly radicular and medial branches tended to be osseous or muscular in nature. The largest branches of the VA originated from its V-3 segment or the C2-3 part of its V-2 segment. Rarely, branches to the extracranial glossopharyngeal and spinal accessory nerves were identified originating from the V-3 and V-2 segments of the VA, respectively. Conclusions. Although seemingly diverse in their distribution, the branches of the V-2 and V-3 segments of the VA may follow a certain consistent arrangement. The potential for injury to neural branches of the VA is minimal at its V-3 segment and the C1-2 portion of its V-2 segment. Such knowledge may be of use to the neurosurgeon who operates in the neck and at the craniocervical junction. (DOI:10.3171/2009.3.SPINE08683)