intervertebral veins

{{Contradict|about=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.|date=August 2023}}{{Infobox vein

| Name = Intervertebral veins

| Latin = vena intervertebralis

| Image = Gray578.png

| Caption = Transverse section of a thoracic vertebra, showing the vertebral venous plexuses.

| Image2 = Gray579.png

| Caption2 = Median sagittal section of two thoracic vertebrae, showing the vertebral venous plexuses.

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The intervertebral veins accompany the spinal nerves through the intervertebral foramina to drain the internal vertebral venous plexuses into the external vertebral venous plexuses.{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |publisher= |year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=453}} They drain (in craniocaudal sequence) into vertebral vein, intercostal veins, lumbar veins, and lateral sacral veins. Upper posterior intercostal veins may additionally drain via brachiocephalic vens. They may drain to ascending lumbar veins. They may drain into the inferior vena cava directly, reaching it by winding around the surface of the vertebral body.{{Cite book |last=Standring |first=Susan |url=https://www.worldcat.org/oclc/1201341621 |title=Gray's Anatomy: The Anatomical Basis of Clinical Practice |year=2020 |isbn=978-0-7020-7707-4 |edition=42nd |location=New York |pages=882 |oclc=1201341621}}

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).