The Anatomy of the Subclavian Vein

Table of Contents
View All
Table of Contents

The subclavian vein is a large paired, deep vein that extends along each side of the neck.

Deep veins are those located deep in the body to protect the larger veins from injury. The primary function of veins is to transport deoxygenated blood from all parts of the body, returning it to the heart, and then on to the lungs to be reoxygenated.

Both subclavian veins—right and left—are located underneath the clavicle (collarbone). They connect with the jugular veins—one on each side of the neck—to form the brachiocephalic veins, which are sometimes referred to as innominate veins. Without the veins and arteries continuously circulating blood throughout the body, a person would be unable to live.

subclavian vein

MedicalRF.com / Getty Images

Anatomy

The subclavian vein is a continuation of the axillary vein, which is located under the arm. The subclavian vein extends along the medial (middle) side of a muscle called the anterior scalene muscle.

From there, the subclavian vein continues to the outer border of the first rib where it then joins the internal jugular vein to form the brachiocephalic vein (also called the innominate vein). The brachiocephalic vein joins one of the largest veins in the body called the superior vena cava, where the blood is drained directly into the left atrium of the heart.

As each subclavian vein empties blood from the upper extremities to carry the blood back to the heart, they connect with smaller veins (such as the jugular veins) on each side of the body. These smaller veins are called tributaries. Tributaries are veins that drain waste products into a larger vein. The main tributaries of the subclavian vein include the:

  • External jugular vein
  • Dorsal scapular vein
  • Anterior jugular veins

Size

The subclavian vein diameter is approximately 2 cm, which is nearly the same size as your pinky finger.

Structure

Every type of blood vessel—including veins, arteries, and capillaries—has a similar structure but can slightly differ. Each blood vessel is structured as a hollow tube with a lumen (inner open space) that allows blood to run through the vessel. The width of the blood vessel and the walls of the vessel may differ, depending on the type of vessel.

The three layers that comprise the structure of veins include:

  • The tunica intima: The innermost, thin layer of the vein which is comprised of a single layer of endothelial cells.
  • The tunica media: The middle layer of veins.
  • The tunica adventitia: The outer layer of veins that is comprised of connective tissues and nerves; this is the thickest layer of the vein.

Location

The left subclavian vein and the right subclavian vein arise as a continuation of the vein that is under the arm, called the axillary vein; there is one axillary vein extending from under the arm on each side of the body.

The subclavian veins originate at the outer border of the first rib.

Both subclavian veins end by meeting with the jugular veins to form the brachiocephalic, which joins with the superior vena cava vein—where the blood is returned to the heart.

Anatomical Variations

A congenital defect is an abnormality occurring during fetal development. It is commonly referred to as a birth defect. Congenital defects of the subclavian vein are not as prevalent as other types of congenital defects, but there have been some case reports.

Function

The primary function of the subclavian vein is to drain deoxygenated blood from the upper region of the body—including the arms and the shoulder areas—and transport it back to the heart. Another important function of the subclavian is to collect lymph fluid from the lymphatic system from the internal jugular vein.

Clinical Significance

In a clinical setting, the subclavian vein has traditionally been considered as a location for the insertion of a catheter, which is used to deliver intravenous (IV) fluids and/or medications directly into the bloodstream. This is known as a central venous catheter, sometimes referred to as a central line.

There are some advantages and disadvantages of using the subclavian vein to insert a central line, these include:

Advantages of Using the Subclavian for a Central Line

  • The subclavian vein has a predictable course—compared with other veins such as the jugular vein.
  • The location is cosmetically acceptable.

Disadvantages of Using the Subclavian for a Central Line

  • There is a high risk of the subclavian vein becoming stenotic (abnormal thickening and narrowing of a vein) due to venipuncture.
  • Higher risk of pneumothorax—a collection of air between the thin layer of tissue that covers the chest cavity and lungs.
  • Higher risk of catheter-related deep vein thrombosis or DVT, which often results in swelling and pain in the arm, requiring removal of the catheter and/or anticoagulant thrombolytic treatment.
Was this page helpful?
Article 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.
  1. National Cancer Institute. Introduction to the Cardiovascular System.

  2. Fortune JB. Effect of patient position on size and location of the subclavian vein for percutaneous puncture. Arch Surg. 2003;138(9):996. doi:10.1001/archsurg.138.9.996

  3. Nadesan T, Keough N, Suleman FE, Lockhat Z, van Schoor AN. Appraisal of the surface anatomy of the Thorax in an adolescent population. Clin Anat. 2019 Sep;32(6):762-769. doi:10.1002/ca.23351 

  4. Wolfe, Y. Bhargava, V. Lobo, V. American College of Emergency Physicians. Emergency ultrasound. Tips and tricks: US-guided subclavian vein.

  5. Schwarz K, Pitcher DW. Congenital subclavian arteriovenous fistula. Case Reports. 2009;2009(dec17 1):bcr0920092312-bcr0920092312. doi:10.1136/bcr.09.2009.2312 

  6. Anatomy.net. Subclavian vein.

  7. Funaki B. Central venous access: a primer for the diagnostic radiologistAmerican Journal of Roentgenology. 2002;179(2):309-318. doi:10.2214/ajr.179.2.1790309