---
title: "External Iliac Arteries | Anatomy and Physiology I"
description: "External iliac arteries are paired vessels that carry oxygenated blood from the common iliac arteries to the femoral arteries in Anatomy and Physiology I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/external-iliac-arteries"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 20"
---

# External Iliac Arteries | Anatomy and Physiology I

## Definition

The external iliac arteries are paired arteries that continue from the common iliac arteries and carry oxygenated blood toward the lower limbs. In Anatomy and Physiology I, they are the main arterial route that becomes the femoral arteries after passing under the inguinal ligament.

## What It Is

The external iliac arteries are the main arterial pathway that carries oxygen-rich blood from the pelvis into each lower limb. In Anatomy and Physiology I, you usually meet them as the next step after the common iliac arteries split from the abdominal aorta.

Each external iliac artery runs along the pelvic brim, which is the edge of the bony pelvis. That location matters because the vessel is still in the pelvic region for part of its path, but it is already heading toward the leg. The pelvic brim gives you a visual landmark for tracing the artery on diagrams or cadaver images.

As the vessel continues downward, it passes deep to the inguinal ligament. Once it crosses that landmark, its name changes to the femoral artery. That name change is a common anatomy exam point, because it shows how blood vessels are often renamed based on body region rather than because they become a completely different structure.

Functionally, the external iliac arteries are part of the systemic circuit, so they carry blood that has already been oxygenated by the lungs and pumped out of the left side of the heart. Their job is to make sure the pelvis and lower limbs receive enough oxygen and nutrients for muscle activity, tissue repair, and normal metabolism.

A simple way to track the pathway is: abdominal aorta, common iliac arteries, external iliac arteries, femoral arteries. If a diagram asks where blood goes next, the key clue is the inguinal ligament. Above it, you are still in the external iliac artery. Below it, you are in the femoral artery.

This term also comes up when you compare the arteries of the pelvis with the arteries of the leg. The external iliac artery is not the only vessel near the pelvis, but it is the main continuation that feeds the lower limb. That is why it shows up in circulatory pathway diagrams, vessel ID activities, and questions about blood flow to the legs.

## Why It Matters

External iliac arteries show how Anatomy and Physiology I connects structure to function. You are not just memorizing a vessel name, you are tracing how blood gets from the heart to the lower limb without losing its route.

This term also helps you follow vessel naming patterns. Many anatomy questions test whether you can identify where a vessel starts, where it ends, and what it becomes after crossing a landmark. The external iliac artery is a clean example because the transition to the femoral artery happens at the inguinal ligament, a structure you can point to on a diagram.

It also matters for circulation problems and case-style questions. If blood flow is narrowed in the external iliac artery, the lower limb may receive less oxygenated blood, which can affect walking, healing, and tissue health. That kind of cause and effect shows up when you connect anatomy to symptoms.

Finally, it reinforces the idea that arteries are defined by direction away from the heart, not by the oxygen level of the blood they carry. In the systemic circuit, the external iliac arteries carry oxygenated blood, which is exactly what you want to recognize when comparing them with veins in the same region.

## Connections

### Aorta

The aorta is the main highway out of the left ventricle, and the external iliac arteries sit much farther down that route. Blood reaches the external iliac arteries only after moving from the abdominal aorta into the common iliac arteries. That makes the aorta the starting point for tracing lower-body arterial flow on diagrams and pathway questions.

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

The abdominal aorta is the part of the aorta that descends through the abdomen before it splits into the common iliac arteries. Since the external iliac arteries come from that split, the abdominal aorta is the larger vessel you trace first when following blood toward the pelvis and legs. It is the parent vessel in this pathway.

### [Femoral Artery](/anatomy-physiology/key-terms/femoral-artery)

The femoral artery is the continuation of the external iliac artery after it passes beneath the inguinal ligament. This relationship is one of the easiest anatomy naming changes to remember because the vessel keeps going, but its regional name changes. If you see a vessel below the inguinal ligament, you should think femoral artery, not external iliac artery.

### Pelvic Brim

The pelvic brim is the bony edge along which the external iliac arteries run as they leave the abdominal cavity area and head toward the leg. It works like a landmark for orientation, especially on anatomy models or cross-section drawings. If you can spot the pelvic brim, you can often trace the external iliac artery more confidently.

## On the AP Exam

A quiz label or diagram question may ask you to trace blood flow to the lower limb, and this is where you name the external iliac arteries in order. You might also be asked to identify the vessel that becomes the femoral artery after it passes under the inguinal ligament. On a labeled model, the key move is to use location, not just memorization, because the same vessel changes name by region. In a case question about reduced circulation to the leg, you may need to explain that a blockage in the external iliac artery can reduce oxygen delivery below the pelvis and affect the femoral supply route.

## External Iliac Arteries vs Femoral Artery

These are the same continuous vessel in different regions, so they are easy to mix up. The external iliac artery is the segment above the inguinal ligament, while the femoral artery is the segment below it. If a question gives you an image or landmark, use the inguinal ligament to decide which name fits.

## Key Takeaways

- The external iliac arteries carry oxygenated blood from the common iliac arteries toward the lower limbs.
- They run along the pelvic brim and become the femoral arteries after passing beneath the inguinal ligament.
- This is a name change based on anatomical location, not a change into a different vessel type.
- In Anatomy and Physiology I, you use this term to trace lower-body blood flow and identify vessel landmarks on diagrams.
- Problems with this artery can reduce blood supply to the pelvis and leg, which makes the pathway clinically relevant.

## FAQs

### What is the external iliac artery in Anatomy and Physiology I?

The external iliac artery is the paired artery that carries oxygenated blood from the common iliac arteries toward the leg. It runs along the pelvic brim and becomes the femoral artery after it passes under the inguinal ligament. That name change is a common anatomy landmark question.

### Is the external iliac artery the same as the femoral artery?

They are continuous, but not named the same in the same region. The external iliac artery is the part above the inguinal ligament, and the femoral artery is the part below it. Anatomy questions often test whether you know that vessel names change by location.

### Where does the external iliac artery come from?

It branches from the common iliac artery, which comes from the abdominal aorta. If you are tracing blood flow from the heart to the lower limb, the route goes abdominal aorta, common iliac artery, external iliac artery, then femoral artery. That sequence is worth memorizing in order.

### Why do external iliac arteries matter in blood flow to the legs?

They are the main arterial pathway delivering oxygenated blood from the pelvis into the lower limb. If flow is reduced here, the leg can receive less oxygen and nutrients. That is why this vessel shows up in circulation diagrams and in questions about impaired blood supply.

## Related Study Guides

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

## About This Document

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- [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing
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