Veins of the Vertebral Column
The vertebral column is an aggregate structure, normally made up of 33 vertebrae and the components that unite them into a single structural, functional entity – the “axis” of the axial skeleton. In the normal erect posture, the vertebral column supports the head and trunk on the pelvis. This support is maintained by the bodies of the vertebrae and the intervertebral discs, which thus become progressively larger from above downwards.
As it provides the semi-rigid, central core about which movements of the trunk occur, soft or hollow structures that run a longitudinal course are subject to damage or kinking (e.g., the spinal cord, descending part of the aorta, inferior and superior vena cavae, thoracic duct, and esophagus ). Thus they lie in close proximity to the vertebral axis, where they receive its semi-rigid support and torsional stresses on them are minimized.
To meet the supportive and other important functions, the vertebral column requires an adequate supply of nutrients. Hence, it is richly supplied by blood vessels, like the periosteal and equatorial branches of the major cervical and segmental arteries.
The vertebral column also provides good venous drainage.
Vertebral Venous System
The vertebral column is drained by plexuses (networks) of veins. These venous plexuses are formed by spinal veins along the vertebral column, both inside and outside the vertebral canal. The plexuses include:
- Internal vertebral venous plexus (or the epidural venous plexus)
- External vertebral venous plexuses
Both of these two venous plexuses communicate through the intervertebral foramina. They are most dense anteriorly and posteriorly and relatively sparse laterally. Most of the vertebral veins parallel the arterial supply, and the large, tortuous basivertebral veins form within the vertebral bodies. These basivertebral veins emerge from foramina on the surfaces of the vertebral bodies (mostly the posterior aspect) and drain into the anterior external and especially the anterior internal vertebral venous plexuses, which may form large longitudinal sinuses.
Another important group of veins of the vertebral column are the intervertebral veins. They receive blood from the veins of the spinal cord and internal vertebral venous plexuses as they accompany the spinal nerves through the intervertebral (IV) foramina. The internal plexus drains into the external one, which in turn drains into the vertebral veins of the neck and segmental (intercostal, lumbar, and sacral) veins of the trunk.