Location of internal vertebral venous plexus?

• A. Subarachnoid space
• B. Extradural (epidural) space
• C. Subdural space
• D. Intraspinal fat

Answer: (B)

The internal vertebral venous plexus is located in the extradural (epidural) space of the spinal canal, the space between the dura mater and the vertebral periosteum. This epidural space also contains fat and a large, valveless venous network. Because these veins lack valves, they form a continuous, bidirectional route that communicates with the external vertebral venous plexus and systemic veins, allowing spread of infection or metastasis along the spine. The subarachnoid space is the CSF-filled space inside the arachnoid and pia mats; the subdural space is a potential space between dura and arachnoid; and adipose tissue can be found in the epidural space, but the venous plexus itself resides specifically in that extradural compartment.