---
title: "Median Sacral Artery | Anatomy and Physiology I"
description: "Median sacral artery: a small unpaired branch of the abdominal aorta that supplies the sacrum and coccyx in Anatomy and Physiology I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/median-sacral-artery"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 20"
---

# Median Sacral Artery | Anatomy and Physiology I

## Definition

The median sacral artery is a small, unpaired artery that branches from the posterior abdominal aorta just above its split into the common iliac arteries. It carries blood to the sacrum and coccyx.

## What It Is

The median sacral artery is a small midline artery in Anatomy and Physiology I that comes off the back of the abdominal aorta just before the aorta divides into the common iliac arteries. From there, it travels downward over the front of the sacrum toward the coccyx and gives blood to the lower part of the vertebral column and nearby tissues.

What makes it easy to miss is its size and position. It is not one of the big named branches students usually memorize first, like the renal arteries or common iliac arteries. Instead, it is a narrow, unpaired vessel that sits right in the center line, so on diagrams it may look like a thin continuation dropping from the aorta.

Its course matters because the aorta is ending at that point. The median sacral artery is part of the transition from one large trunk to the arterial supply of the pelvis and lower body. Even though it is small, it still fits the same basic arterial pattern you see throughout the circulatory system: oxygenated blood leaves a larger artery, then feeds a specific region through a smaller branch.

This artery mainly supplies the sacrum and coccyx, the bony structures at the base of the vertebral column. Those bones are not just passive supports. They are part of the pelvis, they anchor ligaments and muscles, and they sit near tissues that still need a steady blood supply for maintenance and healing.

You may also see it described as a remnant of the embryonic continuation of the dorsal aorta. For A&P I, you usually do not need to chase that history unless your instructor brings up development. What matters more is knowing where it starts, where it travels, and what region it supplies.

A common way to visualize it is to picture the abdominal aorta ending and splitting left and right into the common iliac arteries, with a thin middle branch continuing downward. That middle branch is the median sacral artery. If a diagram asks you to identify the vessel in the midline just above the aortic bifurcation, this is the one you are looking for.

## Why It Matters

The median sacral artery shows how vascular anatomy is organized by region, not just by big textbook vessels. In Anatomy and Physiology I, you are not only naming arteries, you are tracing where blood goes and why a structure gets that supply. This artery is a good example of a small branch that still has a real anatomical job.

It also helps you map the end of the abdominal aorta. Once you can place the median sacral artery, it becomes easier to picture the aortic bifurcation, the common iliac arteries, and the way the body routes blood into the pelvis. That makes pelvic circulation less of a memorized list and more of a connected pathway.

The term also shows up when you study the bony pelvis and spinal region. The sacrum and coccyx may seem like simple bones to label, but their blood supply matters for tissue health, injury repair, and understanding nearby vessels during dissection or imaging. If you are reading an anatomy diagram or identifying structures in lab, knowing this vessel can help you avoid confusing it with the neighboring iliac branches.

For circulation pathway work, it is a reminder that not every artery serves a huge organ. Some arteries are small, direct suppliers to bones and connective tissue. That detail makes the circulatory system feel more precise, because each branch reflects the needs of a specific region.

## Connections

### [Abdominal Aorta](/anatomy-physiology/key-terms/abdominal-aorta)

The median sacral artery branches from the abdominal aorta near its lower end. If you know the aorta’s course and where it bifurcates, you can place this vessel in the correct spot on a diagram. It is one of the last small branches before the blood flow is routed into the right and left common iliac arteries.

### Sacrum

The sacrum is one of the main structures supplied by the median sacral artery. In A&P I, this connection helps link circulation to skeletal anatomy, since bones still need blood for maintenance and healing. If you are labeling the pelvis, the artery and bone often appear close together.

### Coccyx

The coccyx sits just below the sacrum, and the median sacral artery helps supply that lower terminal part of the vertebral column. This is useful when you are studying how vessels follow body regions rather than just organs. It also helps explain why small midline arteries can matter in the pelvis.

### [Aortic Arch](/anatomy-physiology/key-terms/aortic-arch)

The aortic arch is another major aortic landmark, but it is much higher in the body and gives off branches to the head, neck, and upper limbs. Comparing it with the median sacral artery helps you see how the aorta changes its branches as it travels from the thorax down into the abdomen and pelvis.

## On the AP Exam

A diagram label question may point to a thin midline artery coming off the back of the abdominal aorta just above the bifurcation, and you would identify it as the median sacral artery. In a practical or image-based quiz, you might need to trace blood flow from the abdominal aorta into a pelvic branch and name the vessel.

It can also show up in short-answer questions about blood supply to the sacrum or coccyx. If your instructor asks which artery supplies the lower vertebral column at the midline, this is a good term to know. When you study circulation pathways, use it as a landmark for the transition from the abdominal aorta to the common iliac arteries.

## Key Takeaways

- The median sacral artery is a small unpaired branch of the abdominal aorta near its lower end.
- It runs in the midline, which makes it easy to spot on anatomy diagrams if you know where the aorta bifurcates.
- Its main job is to supply the sacrum and coccyx.
- This vessel is a good reminder that even small arteries matter because they deliver blood to specific structures.
- Knowing it helps you connect circulatory anatomy with the pelvis and lower vertebral column.

## FAQs

### What is the median sacral artery in Anatomy and Physiology I?

It is a small, unpaired artery that arises from the posterior abdominal aorta just above the point where the aorta splits into the common iliac arteries. It supplies the sacrum and coccyx. In A&P I, it shows up as part of the lower abdominal and pelvic circulation.

### Where does the median sacral artery come from?

It usually comes off the back of the abdominal aorta near its terminal bifurcation. That location matters because it sits right at the transition between the main abdominal trunk and the arteries that head into the pelvis. On a diagram, look for a thin midline branch dropping down from the aorta.

### What does the median sacral artery supply?

Its main supply area is the sacrum and coccyx. That means it provides blood to the lower part of the vertebral column and nearby tissues. In a lab image or test question, the clue is usually the combination of a midline artery and a pelvic bone target.

### How is the median sacral artery different from the common iliac arteries?

The common iliac arteries are the large paired vessels that form when the abdominal aorta bifurcates. The median sacral artery is much smaller and unpaired, and it continues in the midline between them. That size and position difference is what helps you tell them apart.

## Related Study Guides

- [20.5 Circulatory Pathways ](/anatomy-physiology/unit-20/5-circulatory-pathways/study-guide/nKkAS5lkN4RVf6Kk)

## About This Document

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