Venous drainage of the spinal cord and the vertebral column is accomplished by an extensive series of venous plexuses that are found both within and outside the vertebral canal. All parts of these venous plexuses anastomose without valves, making the venous plexuses of the vertebral column a reservoir for blood shifted from the body cavities and a route for metastasis (18). The importance of accurate knowledge of the vertebral plexuses, emphasized by the development of interventional radiology, has prompted examination of these plexuses using modern imaging techniques (19).
The internal venous plexuses are the anterior and posterior internal vertebral venous plexuses. The anterior internal vertebral venous plexus consists of longitudinal and transverse channels and lies in the epidural space in the vicinity of the posterior longitudinal ligament. Indeed, the posterior longitudinal ligament is thought to help compartmentalize the anterior internal vertebral venous plexus (20). The longitudinal channels receive the basivertebral veins, which are endothelial lined sinuses within the vertebral bodies. Superiorly, the anterior internal vertebral venous plexus communicates with the basilar and occipital sinuses, the sigmoid sinuses, and the vein of the hypoglossal canal.
The anterior external vertebral venous plexus is related to the anterior longitudinal ligament. The posterior external vertebral venous plexus is formed by veins in the vicinity of the spinous, transverse, and articular processes of the vertebrae. The anterior and posterior external plexuses communicate with the internal plexuses and all are tributaries to veins corresponding to the spinal branches of the segmental arteries.
The vertebral veins arise in the suboccipital region by the confluence of spinal branches of the segmental veins and muscular veins. The vertebral veins descend through the transverse foramina with the vertebral artery as an accompanying plexus. The vertebral veins receive the segmental and muscular veins at each level in the neck. The vertebral veins exit the foramina at C6 and drain into the right and left brachiocephalic veins.
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