---
title: "Ulnar Artery | Anatomy and Physiology I"
description: "The ulnar artery is a major forearm artery that supplies blood to the hand and forearm in Anatomy and Physiology I, often studied with the radial artery."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/ulnar-artery"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 20"
---

# Ulnar Artery | Anatomy and Physiology I

## Definition

The ulnar artery is one of the two main arteries of the forearm. In Anatomy and Physiology I, you study it as a branch of the brachial artery that supplies blood to the forearm and hand.

## What It Is

The ulnar artery is a major artery in the forearm in Anatomy and Physiology I, where you learn it as a branch of the brachial artery that carries oxygenated blood toward the hand. It runs along the medial side of the forearm, which means the pinky side in anatomical position.

It usually begins at the elbow region, where the brachial artery divides into the radial artery and ulnar artery. From there, the ulnar artery travels down the forearm and contributes to blood supply for many muscles, connective tissues, and structures in the hand. Because arteries carry blood away from the heart, the ulnar artery is part of the delivery system that keeps working tissues supplied with oxygen and nutrients.

The ulnar artery does not work alone. It connects with other vessels and helps form the arterial arches in the hand, especially the superficial palmar arch. Those connections matter because blood can still reach the hand through more than one route, which adds a backup pathway if one vessel is narrowed or blocked. That redundancy is a common theme in the circulatory system.

A lot of students first meet the ulnar artery while tracing blood flow through the upper limb. The easiest way to place it is to remember the sequence: brachial artery in the arm, then division into the radial and ulnar arteries near the elbow, then circulation through the forearm and hand. If you picture the forearm in anatomical position, the radial artery is on the thumb side and the ulnar artery is on the pinky side.

In lab or on an image quiz, the ulnar artery is often identified by location rather than by a huge list of branches. You are usually expected to know where it is, what direction blood moves, and how it fits into the larger pattern of circulatory pathways. The term is not just a label, it is part of the route blood takes from the heart to the upper limb and back through the veins.

## Why It Matters

The ulnar artery matters because it is one of the clearest examples of how Anatomy and Physiology I connects structure to function. You are not just memorizing a name. You are learning how a named vessel fits into the path that delivers oxygenated blood to the forearm and hand.

This term also comes up when you compare the upper limb arteries. The radial artery and ulnar artery are paired in a way that makes location-based questions easier to answer. If you can place the ulnar artery on the medial side of the forearm and connect it to the brachial artery, you can usually trace the rest of the circulatory pathway more confidently.

It also reinforces a bigger circulatory idea: arteries branch, reconnect, and distribute blood through networks. That network matters in the hand, where blood supply has to support movement, grip, and fine motor control. When you study the ulnar artery, you are also seeing how the body builds alternate routes so tissues stay perfused even when one pathway is less efficient.

In practical class work, this term often appears in diagrams, vessel-tracing questions, and anatomy identification activities. Knowing the ulnar artery helps you read those visuals faster and explain why the vessel is placed where it is. It is a small term with a big payoff because it sits right in the middle of the circulatory pathway content.

## Connections

### [Brachial Artery](/anatomy-physiology/key-terms/brachial-artery)

The brachial artery is the parent vessel that gives rise to the ulnar artery near the elbow. If you know the brachial artery pathway first, it becomes much easier to place the ulnar artery as part of the next step in blood flow through the upper limb. This relationship is often tested in vessel-tracing questions and anatomy diagrams.

### [Radial Artery](/anatomy-physiology/key-terms/radial-artery)

The radial artery is the ulnar artery’s main partner in the forearm. They split from the brachial artery and run on opposite sides of the forearm, which is why location clues matter so much. Students often confuse them at first, so comparing thumb side versus pinky side is a useful way to keep them straight.

### Circulatory Pathways

The ulnar artery is one piece of the larger circulatory pathway that moves blood from the heart to body tissues. In this unit, you are expected to follow flow logically, not just memorize vessel names. The ulnar artery shows how blood is distributed through branching vessels after leaving the larger arteries.

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

The aortic arch is much farther upstream in the arterial system, but it helps you understand how blood ultimately reaches the upper limbs. From the arch, major branches eventually lead to arteries that supply the arm, including the pathway that becomes the brachial artery and then the ulnar artery. It helps place the term in the full route from heart to hand.

## On the AP Exam

A diagram question may ask you to identify the ulnar artery by its position on the medial, pinky side of the forearm. A pathway question may ask you to trace blood from the brachial artery into the radial and ulnar arteries, then into the hand. In lab practicals, you might need to label the vessel on a chart or compare it with the radial artery. Short-answer prompts often focus on direction of flow and vessel type, so remember that it carries oxygenated blood away from the heart and supplies the forearm and hand. If a question uses anatomical position, read left and right carefully, because side labels depend on the body facing forward.

## ulnar artery vs radial artery

These two are commonly mixed up because both are major forearm arteries and both come from the brachial artery. The easiest difference is location: the radial artery is on the thumb side, while the ulnar artery is on the pinky side. If a question gives you a forearm image, orientation in anatomical position is the clue that usually decides it.

## Key Takeaways

- The ulnar artery is one of the two main arteries of the forearm and carries oxygenated blood to the hand.
- It branches from the brachial artery near the elbow and runs along the medial, pinky side of the forearm.
- The ulnar artery works with the radial artery to supply the forearm and contribute to blood flow in the hand.
- Its connections in the hand show how the circulatory system builds backup routes for blood delivery.
- In Anatomy and Physiology I, you usually need to identify it on diagrams, trace its pathway, and compare it with the radial artery.

## FAQs

### What is the ulnar artery in Anatomy and Physiology I?

The ulnar artery is a major artery of the forearm that branches from the brachial artery and carries oxygenated blood toward the hand. In Anatomy and Physiology I, it is usually studied as part of upper-limb circulatory pathways and compared with the radial artery.

### Where is the ulnar artery located?

It runs along the medial side of the forearm, which is the pinky side in anatomical position. That location is one of the fastest ways to tell it apart from the radial artery, which runs on the thumb side.

### What is the difference between the ulnar artery and the radial artery?

Both are branches of the brachial artery and both supply the forearm and hand. The main difference is location: the ulnar artery is medial, while the radial artery is lateral. On diagrams, that side-by-side comparison is usually what you are being tested on.

### Why does the ulnar artery matter in the hand?

It helps supply blood to the muscles and tissues of the hand and contributes to arterial arches that distribute blood more widely. Those connections matter because the hand needs a dependable blood supply for movement, grip, and fine motor control.

## Related Study Guides

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

## About This Document

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