This study of the arterial blood of the spinal cord indicates that, of the 62 radicular branches (rami radiculares), at the most seven or eight truly participate in the vascularization of the spinal cord. The authors have observed that the situation and distribution of these branches enable the distinction of three large arterial areas: cervicothoracic, midthoracic, and thoracolumbar. The fixed nature of the intramedullary arterial distribution contrasts with the variability of the afferent arterial supplies. No demarcation permits separation of the vascularization of the spinal cord into anterior and posterior parts. The anastomotic systems situated on the arterial pathways are potentially valuable, but their functioning is problematical. The anterior spinal artery is not continuous, for in the midthoracic region there exists a critical narrow zone. The perimedullary anastomotic system appears insufficient while intramedullary anastomoses are without functional value.
Few studies have been done about the venous vascularization of the spine since neuroradiologic studies in the 1960s and 70s. The aim of this study was to clarify the topography of the internal vertebral venous plexuses in relation to the posterior longitudinal ligament and the dura. The relationships of the vv. were studied at different levels of the spine. The internal vertebral venous system of seven cadavers was injected with a blue bicomponent silicon rubber. It consisted with an anterior and a posterior venous plexus. At the cervical level, the anterior longitudinal vv. are located in a dehiscence of the periosteal layer, in the lateral part of the spinal canal. At each level, they joined the contralateral one at the midline by a retrocorporeal v. located behind the posterior longitudinal ligament. No vv. were found in the epidural space. There was a major development of the retrocorporeal v. of the axis, but it did not receive any venous drainage from the vertebral body. At the thoracic and lumbar levels, the anterior venous plexuses remain within a dehiscence of the periosteal layer, which is thinner. The retrocorporeal vv. become pre-ligamentous. We did not find any posterior venous plexuses at the cervical level, but they were evident at the thoracic level and became more voluminous and sinusoidal in the lumbar region.
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