---
title: "Axillary Artery | Anatomy and Physiology I"
description: "Axillary artery: the major artery of the armpit that continues the subclavian artery and becomes the brachial artery, supplying the upper limb in A&P I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/axillary-artery"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 20"
---

# Axillary Artery | Anatomy and Physiology I

## Definition

The axillary artery is the main artery in the armpit region of Anatomy and Physiology I. It carries oxygen-rich blood from the subclavian artery toward the upper limb and becomes the brachial artery after the teres major muscle.

## What It Is

The axillary artery is the continuation of the subclavian artery after it passes the outer edge of the first rib. In Anatomy and Physiology I, you learn it as the main blood vessel running through the axilla, or armpit, before it becomes the brachial artery at the lower border of the teres major muscle.

That location matters because the axilla is a traffic hub for structures going to and from the upper limb. The artery travels with the axillary vein and parts of the brachial plexus, so the region is packed with vessels and nerves. When you study body landmarks, this is a good example of how one muscle boundary can mark a change in a vessel name.

The axillary artery is part of the pathway that delivers oxygenated blood to the shoulder, chest wall, and arm. Its branches supply nearby muscles and tissues as the vessel moves through the axilla, then the flow continues into the brachial artery for the rest of the upper arm. So even though the name changes, the blood is still moving along one connected route.

A lot of A&P students mix up vessel names because the same artery gets renamed as it crosses anatomical landmarks. The axillary artery is not a different vessel from the subclavian artery and brachial artery in a functional sense. It is the middle segment of one continuous arterial path, identified by where it is located.

You will usually picture this vessel on diagrams of the upper limb circulation, especially when tracing blood flow from the heart to the fingers. If you can remember the landmarks, first rib to teres major, you can place the axillary artery correctly and avoid confusion with nearby structures in the shoulder and armpit.

## Why It Matters

The axillary artery matters because it sits right in the middle of upper-limb circulation. If you are tracing how blood reaches the arm, shoulder, and hand, this vessel is the bridge between the subclavian artery and the brachial artery. That makes it a useful checkpoint when you map circulation from the heart outward.

It also gives you a clean example of how anatomy uses landmarks to name vessels. In A&P, a structure can keep the same physical continuity while its name changes based on location. The axillary artery is one of the easiest places to see that idea in action, especially when you compare the first rib, the axilla, and the lower border of teres major.

This term also shows up when you are identifying structures on models, images, or diagrams of the shoulder and upper limb. If you know where the artery starts and ends, you can separate it from the subclavian artery above and the brachial artery below. That helps with lab practicals, labeling exercises, and circulation tracing questions.

It is also a good reminder that vessels do not run alone. In the axilla, the artery sits near major nerves and veins, so understanding its position helps you make sense of the whole region instead of memorizing isolated names.

## Connections

### [Subclavian Artery](/anatomy-physiology/key-terms/subclavian-artery)

The subclavian artery comes before the axillary artery in the blood flow pathway. Once it crosses the outer edge of the first rib, its name changes to axillary artery. When you trace circulation in the upper limb, this is the vessel you identify upstream of the armpit region.

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

The brachial artery is the continuation of the axillary artery after it passes the lower border of teres major. In diagrams and lab practicals, students often confuse the name change, but the vessel is still carrying oxygenated blood down the arm. The landmark tells you where the switch happens.

### Teres Major Muscle

Teres major is one of the main landmark muscles for naming the axillary artery. The artery becomes the brachial artery at the lower border of this muscle. In anatomy labs, that boundary is a helpful visual marker for dividing the upper limb into arterial regions.

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

The aortic arch is farther upstream in the arterial system and helps lead blood toward the subclavian arteries. The axillary artery is part of the downstream route that eventually supplies the upper limb. Seeing that sequence helps you move from the heart to the arm without losing the order.

## On the AP Exam

A practical quiz question might ask you to label an upper-limb diagram, trace blood flow, or identify where the subclavian artery becomes the axillary artery. You use the axillary artery by connecting it to the correct landmark, the lateral edge of the first rib, and by knowing where it ends, at the lower border of teres major.

In a lab practical, you may be shown a shoulder model or a cadaver image and asked to distinguish the axillary artery from the brachial artery. On written questions, the fastest move is to follow the pathway and name the segment based on location, not just memorize a list of vessel names.

## axillary artery vs brachial artery

These are easy to mix up because they are continuous segments of the same arterial route. The axillary artery is the segment in the axilla, while the brachial artery is the segment after the lower border of teres major. If a question points to the armpit region, axillary artery is the better match.

## Key Takeaways

- The axillary artery is the main artery in the armpit region and carries oxygen-rich blood toward the upper limb.
- It begins as a continuation of the subclavian artery at the lateral edge of the first rib.
- It becomes the brachial artery after it passes the lower border of the teres major muscle.
- In Anatomy and Physiology I, this vessel is a classic example of how anatomy uses landmarks to rename the same continuous structure.
- If you can place the axilla and teres major on a diagram, you can usually identify the axillary artery without guessing.

## FAQs

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

The axillary artery is the main artery that runs through the axilla, or armpit, and supplies blood to the upper limb. It continues from the subclavian artery and later becomes the brachial artery. In A&P, you usually identify it by its location between the first rib and teres major.

### Where does the axillary artery begin and end?

It begins at the lateral edge of the first rib, where the subclavian artery becomes the axillary artery. It ends at the lower border of the teres major muscle, where it becomes the brachial artery. Those landmarks are the easiest way to place it on a diagram.

### Is the axillary artery the same as the brachial artery?

No, but they are continuous parts of the same arterial pathway. The axillary artery is the segment in the armpit, and the brachial artery is the segment farther down the arm. The name changes when the vessel crosses the teres major landmark.

### Why does the axillary artery matter in upper-limb circulation?

It is the route that carries oxygenated blood from the subclavian artery toward the shoulder and arm. If you are tracing blood flow or labeling a model, it helps you connect the chest, axilla, and upper arm in the right order. It also shows how vessels are named by location.

## Related Study Guides

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

## About This Document

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