---
title: "Posterior Spinal Veins | Anatomy I"
description: "Posterior spinal veins drain blood from the back of the spinal cord into the vertebral venous plexus in Anatomy and Physiology I, linking spinal circulation."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/posterior-spinal-veins"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 13"
---

# Posterior Spinal Veins | Anatomy I

## Definition

Posterior spinal veins are the veins along the back of the spinal cord that drain deoxygenated blood from spinal tissues. In Anatomy and Physiology I, they are part of the spinal cord’s venous return system and connect with the vertebral venous plexus.

## What It Is

Posterior spinal veins are a venous network on the back, or posterior side, of the spinal cord in Anatomy and Physiology I. Their job is to collect deoxygenated blood from the spinal cord and nearby tissues and move it toward larger drainage pathways.

These veins do not work alone. They form a mesh of channels that anastomose, or connect, with the anterior spinal veins. That connection matters because the spinal cord needs more than one route for blood to leave, especially when one small vessel is compressed or blood flow changes with body position.

Blood enters the posterior spinal veins from smaller radicular veins. Those radicular veins run alongside spinal nerves as the nerves pass through the intervertebral foramina, so they act like connectors between the cord and the larger venous system around the vertebral column. If you picture the spinal cord as a long central structure, the posterior spinal veins are one of the main drainage lines running along its back surface.

After collecting blood, the posterior spinal veins drain into the vertebral venous plexus. That plexus sits inside the vertebral canal and links onward to vertebral, azygos, and intercostal veins. This creates a flexible drainage network that can route blood in more than one direction depending on pressure and body position.

A helpful way to think about it is that the posterior spinal veins are not isolated tubes, but part of a pressure-sharing network. In the spinal canal, veins often have thin walls and low pressure, so connections between vessels make the system more adaptable. That is why A&P classes often group the posterior spinal veins with the anterior spinal veins, radicular veins, and vertebral venous plexus as one connected drainage pathway for the spinal cord.

## Why It Matters

Posterior spinal veins matter because they show how the spinal cord stays supplied and drained as part of the central nervous system. In Anatomy and Physiology I, you are not just memorizing a vessel name, you are tracing how blood leaves the spinal cord after tissues use oxygen and nutrients.

This term also helps you make sense of how the spinal cord is organized around both arteries and veins. The spinal arteries bring blood in, and the spinal veins carry it away. If you understand that the posterior spinal veins are part of the drainage side, the whole circulatory picture becomes easier to follow.

They also connect to several other course ideas, like the vertebral venous plexus and the spinal nerves exiting through intervertebral foramina. That is useful when you are labeling diagrams, following a lab model, or answering questions that ask how structures in the vertebral canal are related.

The concept comes up again when you think about circulation changes with posture or pressure. Because the spinal venous system has many connections, it can serve as a backup route for blood flow. That is a good example of how anatomy supports homeostasis, even in a small, local vessel network.

## Connections

### Anterior Spinal Veins

The posterior spinal veins connect with the anterior spinal veins through anastomoses, so they function as part of one drainage network around the spinal cord. If you are tracing venous return on a diagram, the posterior system is the back-side pathway, while the anterior system runs along the front. Together, they help move blood out of spinal tissues.

### Radicular Veins

Radicular veins feed into the posterior spinal veins after traveling with spinal nerves through the intervertebral foramina. That makes them the smaller connecting vessels between the cord and the larger venous network. When you study spinal circulation, radicular veins explain how blood from the cord reaches the veins along its surface.

### Vertebral Venous Plexus

The posterior spinal veins drain into the vertebral venous plexus, so this plexus is the next step in venous return. In A&P diagrams, it often looks like a web of veins inside the vertebral canal. Knowing this connection helps you follow blood from the cord into broader drainage routes.

### [Arachnoid Mater](/anatomy-physiology/key-terms/arachnoid-mater)

Arachnoid mater is one of the meninges that surrounds the central nervous system, so it sits near the structures involved in spinal circulation. It does not carry blood itself, but it helps frame where the spinal cord and its vessels are located. That spatial relationship matters when you are identifying layers in a cross-section.

## On the AP Exam

A label question may ask you to identify a vessel on the posterior side of a spinal cord diagram, or a matching item may pair the posterior spinal veins with venous drainage of the cord. In short-answer responses, you may need to trace the path of blood from spinal tissues into the vertebral venous plexus. On lab practicals, look for the vessel network running along the back of the cord and distinguish it from the anterior spinal veins. If a question asks how the spinal cord drains, this term is part of the chain you name and explain.

## Key Takeaways

- Posterior spinal veins are the venous channels along the back of the spinal cord that carry deoxygenated blood away from spinal tissues.
- They connect with the anterior spinal veins, so the cord has a linked drainage network instead of a single route.
- Radicular veins feed into the posterior spinal veins as they travel with spinal nerves through the intervertebral foramina.
- The posterior spinal veins drain into the vertebral venous plexus, which continues blood return into larger veins.
- In Anatomy and Physiology I, this term shows how the central nervous system is supported by a flexible venous drainage system.

## FAQs

### What is posterior spinal veins in Anatomy and Physiology I?

Posterior spinal veins are the veins on the back side of the spinal cord that drain deoxygenated blood away from spinal tissues. In Anatomy and Physiology I, they are part of the venous system of the central nervous system and connect with the vertebral venous plexus.

### How are posterior spinal veins different from anterior spinal veins?

The posterior spinal veins run along the back of the spinal cord, while the anterior spinal veins run along the front. They are not separate, isolated systems, because they anastomose and help form one connected drainage network for the cord.

### What drains into the posterior spinal veins?

Radicular veins drain into the posterior spinal veins. Those veins travel with spinal nerves through the intervertebral foramina, so they connect the spinal cord’s smaller drainage channels to the larger venous network on its surface.

### Where do posterior spinal veins drain?

They drain into the vertebral venous plexus. From there, blood can continue into veins such as the vertebral, azygos, and intercostal veins, which carry venous blood away from the spinal region.

## Related Study Guides

- [13.3 Circulation and the Central Nervous System ](/anatomy-physiology/unit-13/3-circulation-central-nervous-system/study-guide/CvPockAsqI7E7aok)

## About This Document

Canonical Fiveable pages are available as Markdown at the same path plus `.md`.

- [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns
- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
- [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`)
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