Internal vertebral venous plexuses
Encyclopedia
The internal vertebral venous plexuses (intraspinal veins) lie within the vertebral canal in the epidural space
, and receive tributaries from the bones and from the medulla spinalis.
They form a closer network than the external plexuses, and, running mainly in a vertical direction, form four longitudinal veins, two in front and two behind; they therefore may be divided into anterior and posterior groups.
The anterior and posterior plexuses communicate freely with one another by a series of venous rings (retia venosa vertebrarum), one opposite each vertebra.
Around the foramen magnum they form an intricate network which opens into the vertebral veins and is connected above with the occipital sinus
, the basilar plexus
, the condyloid emissary vein, and the rete canalis hypoglossi.
Epidural space
In the spine, the epidural space is the outermost part of the spinal canal. It is the space within the canal lying outside the dura mater...
, and receive tributaries from the bones and from the medulla spinalis.
They form a closer network than the external plexuses, and, running mainly in a vertical direction, form four longitudinal veins, two in front and two behind; they therefore may be divided into anterior and posterior groups.
- The anterior internal plexuses consist of large veins which lie on the posterior surfaces of the vertebral bodies and intervertebral fibrocartilages on either side of the posterior longitudinal ligamentPosterior longitudinal ligamentThe posterior longitudinal ligament is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebræ, from the body of the axis, where it is continuous with the membrana tectoria, to the sacrum....
; under cover of this ligament they are connected by transverse branches into which the basivertebral veinsBasivertebral veinsThe basivertebral veins emerge from the foramina on the posterior surfaces of the vertebral bodies.They are contained in large, tortuous channels in the substance of the bones, similar in every respect to those found in the diploë of the cranial bones....
open.
- The posterior internal plexuses are placed, one on either side of the middle line in front of the vertebral arches and ligamenta flavaLigamenta flavaThe ligamenta flava are ligaments which connect the laminae of adjacent vertebrae, all the way from the axis to the first segment of the sacrum...
, and anastomose by veins passing through those ligaments with the posterior external plexuses.
The anterior and posterior plexuses communicate freely with one another by a series of venous rings (retia venosa vertebrarum), one opposite each vertebra.
Around the foramen magnum they form an intricate network which opens into the vertebral veins and is connected above with the occipital sinus
Occipital sinus
The occipital sinus is the smallest of the cranial sinuses.It is situated in the attached margin of the falx cerebelli, and is generally single, but occasionally there are two....
, the basilar plexus
Basilar plexus
The basilar plexus consists of several interlacing venous channels between the layers of the dura mater over the basilar part of the occipital bone , and serves to connect the two inferior petrosal sinuses....
, the condyloid emissary vein, and the rete canalis hypoglossi.