The vertebral venous plexuses: The internal veins are muscular and external veins have valves

Abstract

The internal and external vertebral venous plexuses (VVP) extend the length of the vertebral column. Authoritative sources state that these veins are devoid of valves, permitting bidirectional blood flow and facilitating the hematogenous spread of malignant tumors that have venous connections with these plexuses. The aim of this investigation was to identify morphologic features that might influence blood flow in the VVP. The VVP of 12 adult cadavers (seven female, mean age 79.5 years) were examined by macro- and micro-dissection and representative veins removed for histology and immunohistochemistry (smooth muscle antibody staining). A total of 26, mostly bicuspid, valves were identified in 19 of 56 veins (34%) from the external VVP, all orientated to promote blood flow towards the internal VVP. The internal VVP was characterized by four main longitudinal channels with transverse interconnections; the maximum caliber of the longitudinal anterior internal VVP veins was significantly greater than their posterior counterparts (P < 0.001). The luminal architecture of the internal VVP veins was striking, consisting of numerous bridging trabeculae (cords, thin membranes and thick bridges) predominantly within the longitudinal venous channels. Trabeculae were composed of collagen and smooth muscle and also contained numerous small arteries and nerve fibers. A similar internal venous trabecular meshwork is known to exist within the dural venous sinuses of the skull. It may serve to prevent venous overdistension or collapse, to regulate the direction and velocity of venous blood flow, or is possibly involved in thermoregulation or other homeostatic processes.

The posterior intercostal vein: A thermoregulatory gateway to the internal vertebral venous plexus

“…They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined. However, orientation of the valves in the intervertebral veins in the present study was consistent with that reported by Stringer et al (). It is therefore clear that at least part of the blood that flows from the intercostal spaces can be delivered to the IVVP.…”

“…In agreement with the present study, Stringer et al () showed that the orientation of valves in the connecting veins was consistent with blood flow towards the IVVP. They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined.…”

“…Therefore, this study did not allow a detailed description of the typology and morphological characteristics of the valves found. However, our observations corresponded to the descriptions of the same valves by Maros () and Stringer et al ().…”

The posterior intercostal vein: A thermoregulatory gateway to the internal vertebral venous plexus

“…They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined. However, orientation of the valves in the intervertebral veins in the present study was consistent with that reported by Stringer et al (). It is therefore clear that at least part of the blood that flows from the intercostal spaces can be delivered to the IVVP.…”

“…In agreement with the present study, Stringer et al () showed that the orientation of valves in the connecting veins was consistent with blood flow towards the IVVP. They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined.…”

“…Therefore, this study did not allow a detailed description of the typology and morphological characteristics of the valves found. However, our observations corresponded to the descriptions of the same valves by Maros () and Stringer et al ().…”

Anatomy and Surgical Implications of the Lumbar Epidural Venous Plexus: A Risk Zone Framework

“…This variability was particularly evident in the anterior component, where the venous lumen was frequently subdivided by trabeculations that ranged from delicate membranous partitions to thicker bridging structures, creating a multilayered channel system rather than a single uninterrupted conduit [ 13 ]. By contrast, the posterior plexus appeared less trabeculated and showed greater segmental and inter-individual irregularity, a pattern also supported by the microsurgical observations of Chaynes et al and the broader structural reassessment by Stringer et al [ 2 , 13 , 15 ].…”

The collateral venous system in late pregnancy: A systematic review of the literature

“…This has been demonstrated in multiple venographic, CT and MRI studies on patients with IVC obstruction (Filler and Edwards, ; Ferris et al, ; Pagani et al, ; Paksoy and Gormus, ; Umeoka et al, ). While it is typically described as an independent pathway, the VVP has multiple anastomoses with the ALV, HAV and AV via the intervertebral veins (Golub et al, ; Stringer et al, ; Griessenauer et al, ), so much so that the present authors agree that the two systems should be considered extensions of each other rather than independent pathways.…”

The posterior intercostal vein: A thermoregulatory gateway to the internal vertebral venous plexus

“…They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined. However, orientation of the valves in the intervertebral veins in the present study was consistent with that reported by Stringer et al (). It is therefore clear that at least part of the blood that flows from the intercostal spaces can be delivered to the IVVP.…”

“…In agreement with the present study, Stringer et al () showed that the orientation of valves in the connecting veins was consistent with blood flow towards the IVVP. They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined.…”

“…Therefore, this study did not allow a detailed description of the typology and morphological characteristics of the valves found. However, our observations corresponded to the descriptions of the same valves by Maros () and Stringer et al ().…”

Anatomy and Surgical Implications of the Lumbar Epidural Venous Plexus: A Risk Zone Framework

“…This variability was particularly evident in the anterior component, where the venous lumen was frequently subdivided by trabeculations that ranged from delicate membranous partitions to thicker bridging structures, creating a multilayered channel system rather than a single uninterrupted conduit [ 13 ]. By contrast, the posterior plexus appeared less trabeculated and showed greater segmental and inter-individual irregularity, a pattern also supported by the microsurgical observations of Chaynes et al and the broader structural reassessment by Stringer et al [ 2 , 13 , 15 ].…”

The collateral venous system in late pregnancy: A systematic review of the literature

“…This has been demonstrated in multiple venographic, CT and MRI studies on patients with IVC obstruction (Filler and Edwards, ; Ferris et al, ; Pagani et al, ; Paksoy and Gormus, ; Umeoka et al, ). While it is typically described as an independent pathway, the VVP has multiple anastomoses with the ALV, HAV and AV via the intervertebral veins (Golub et al, ; Stringer et al, ; Griessenauer et al, ), so much so that the present authors agree that the two systems should be considered extensions of each other rather than independent pathways.…”

The posterior intercostal vein: A thermoregulatory gateway to the internal vertebral venous plexus

“…They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined. However, orientation of the valves in the intervertebral veins in the present study was consistent with that reported by Stringer et al (). It is therefore clear that at least part of the blood that flows from the intercostal spaces can be delivered to the IVVP.…”

“…In agreement with the present study, Stringer et al () showed that the orientation of valves in the connecting veins was consistent with blood flow towards the IVVP. They found such valves in two out of six intervertebral veins whereas in the present study, the number of intervertebral veins equipped with valves could not be determined.…”

“…Therefore, this study did not allow a detailed description of the typology and morphological characteristics of the valves found. However, our observations corresponded to the descriptions of the same valves by Maros () and Stringer et al ().…”

Anatomy and Surgical Implications of the Lumbar Epidural Venous Plexus: A Risk Zone Framework

“…This variability was particularly evident in the anterior component, where the venous lumen was frequently subdivided by trabeculations that ranged from delicate membranous partitions to thicker bridging structures, creating a multilayered channel system rather than a single uninterrupted conduit [ 13 ]. By contrast, the posterior plexus appeared less trabeculated and showed greater segmental and inter-individual irregularity, a pattern also supported by the microsurgical observations of Chaynes et al and the broader structural reassessment by Stringer et al [ 2 , 13 , 15 ].…”

The collateral venous system in late pregnancy: A systematic review of the literature

“…This has been demonstrated in multiple venographic, CT and MRI studies on patients with IVC obstruction (Filler and Edwards, ; Ferris et al, ; Pagani et al, ; Paksoy and Gormus, ; Umeoka et al, ). While it is typically described as an independent pathway, the VVP has multiple anastomoses with the ALV, HAV and AV via the intervertebral veins (Golub et al, ; Stringer et al, ; Griessenauer et al, ), so much so that the present authors agree that the two systems should be considered extensions of each other rather than independent pathways.…”