Anatomy Veins The Anatomy of the Axillary Vein A Large Vein of the Upper Limb, Chest, and Armpit By Mark Gurarie Mark Gurarie LinkedIn Mark Gurarie is a freelance writer, editor, and adjunct lecturer of writing composition at George Washington University. Learn about our editorial process Updated on February 11, 2021 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Yasmine S. Ali, MD, MSCI Medically reviewed by Yasmine S. Ali, MD, MSCI Facebook LinkedIn Twitter Yasmine Ali, MD, is board-certified in cardiology. She is an assistant clinical professor of medicine at Vanderbilt University School of Medicine and an award-winning physician writer. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Anatomy Function Clinical Significance The axillary vein is a major vein in the upper body that carries blood from the upper limb, armpit, and the upper side of the chest wall towards the heart. On each side of the body, it forms where the basilic and brachial veins join in the axilla, a space just below the shoulder that allows arteries, veins, and nerves to pass. Its course is relatively short as it moves upwards towards the middle of the body and terminates into the subclavian vein at the border of the first (topmost) rib. MedicalRF / Getty Images As a deep vein that plays a critical role in upper body circulation, diseases or disorders of the axillary vein can become problematic. In particular, axillary thrombosis—a kind of deep vein thrombosis (DVT), or blood clotting—is a relatively rare, but potentially very dangerous condition. This vein may also sometimes be considered as a means to gain venous access for the placement of a pacemaker, though it’s a riskier alternative. Anatomy Structure The body has an axillary vein on each side, typically varying between 1.1 and 1.2 centimeters (cm) in diameter. Veins are typically a little thinner than arteries, which are the vessels that carry blood away from the heart. They consist of three layers: Tunica intima: The inner lining of veins is composed of a layer of flat cells, called squamous epithelium, in contact with a base membrane that keeps blood inside.Tunica media: The middle layer of veins is smooth muscle, which can apply pressure on the axillary vein to push blood along and help regulate function.Tunica adventita: This thicker, outer layer has elastic fibers that help connect vessels to surrounding tissues for support. Location The axillary vein arises at the lower border of the axilla, just beneath the teres major shoulder muscle, near where the underarm meets the body. Along its course are several important features: Origin: The basilic vein, a primary surface (“superficial”) vein of the arm, and the brachial vein, one of the upper arm’s deep veins, join together to form the axillary vein. Axillary region: The axillary vein travels upwards and towards the middle of the body, crossing the armpit. As it does so, it runs close to the axillary artery along with a bundle of nerves, including the lateral and medial pectoral nerves, the brachial plexus, and the ulnar nerve. Termination: As it crests to the top of the axilla space, another major vein of the arm, the cephalic vein, joins up, and the two terminate into the subclavian vessel. This occurs at the border of the top-most rib. In addition to the cephalic vein, the axillary vein has several other tributaries, which correspond to branches of the axillary artery. These are: Thoracoacromial veinLateral thoracic veinSubscapular veinAnterior circumflexHumeral veinPosterior circumflex humeral vein Anatomical Variations Congenital differences in the anatomy of the axillary vein are relatively common, and many people will display small variations. In particular, accessory axillary vein, in which a small, second vein arises alongside the primary one, may occur in over half the population. The specific position of this second vein varies a great deal, and it may join In addition, doctors have observed different origins for the axillary vein, as the brachial and basilic veins may meet at different positions. Furthermore, the cephalic vein—usually joining near to the end of the axillary vein’s course—may also run into it earlier along. Function The circulatory system’s main job is to deliver oxygen from the lungs to the rest of the body. Blood cells are laden with oxygen in the heart and then pumped out through the arteries. In turn, it’s the veins that bring deoxygenated blood back. Given its position in the body, the axillary vein conveys blood from the axilla, the side of the chest cavity (thorax), and the upper arm. Clinical Significance Clinically speaking, there are a couple cases where the axillary vein comes into play. Cannulation This vein may be considered for cannulation, which means inserting a tube or catheter. Most often, this technique is employed as means to implant a pacemaker near the heart using a minimally-invasive procedure. The axillary vein will be considered in cases where employing other veins is likely to be dangerous. Axillary Vein Thrombosis Blood clotting of the axillary vein is relatively rare in the general population, though it occurs more often in competitive athletes. Repeated strain, injury, or other factors this condition, which leads to swelling, blue color, heaviness, and pain in the arm. If untreated, this condition can lead to pulmonary embolism (blood clot in the lung), stroke, heart failure, and venous insufficiency, among other dangerous conditions. Blood-thinning medications, physical therapy, as well as surgeries, resolve this condition. How Deep Vein Thrombosis Is Treated Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 6 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Sendic G. Axillary vein. Kenhub. Cleveland Clinic. Axillo-subclavian vein thrombosis. Lavallée C, Ayoub C, Mansour A et al. Subclavian and axillary vessel anatomy: a prospective observational ultrasound study. Can J Anesth. 2017;65(4):350-359. doi:10.1007/s12630-017-1032-8 National Cancer Institute. Classification & structure of blood vessels. SEER Training Modules. Debowski M, Hoskins A. Axillary vein: radiology reference article. Radiopaedia. Felix V, Santos J, Fernandes K et al. Anatomical study of the accessory axillary vein in cadavers: a contribution to the axillary surgical approach. J Vasc Bras. 2016;15(4):275-279. doi:10.1590/1677-5449.003616