This article or section appears to contradict itselfon Last's Anatomy states: "The internal vertebral plexus sends its efferent veins (the intervertebral veins) [...] to drain into the external vertebral venous plexus and thence into the segmental veins." This seems to contradict the content referencing Gray's Anatomy.. Please see the talk page for more information.(August 2023)
Intervertebral veins
Transverse section of a thoracic vertebra, showing the vertebral venous plexuses.
Median sagittal section of two thoracic vertebrae, showing the vertebral venous plexuses.
It is unclear whether intervertebral veins contain functional venous valves; blood flow through intervertebral veins may be reversible, suggesting a possible mechanism for metastatic spread of e.g. prostatic cancer to the spine during temporary blood flow reversals (e.g. during periods of elevated intra-abdominal pressure or during postural alterations).[2]