Left superior intercostal vein

At a glance

English

Left superior intercostal vein

Latin (TA2)

Vena intercostalis superior sinistra

System

Vein

Region

Trunk

Side

Single, on the midline

About the left superior intercostal vein

The left superior intercostal vein collects blood from the upper intercostal spaces on the left. It is formed by the posterior intercostal veins of the second and third spaces, and often the fourth as well, which would otherwise have no direct route to the azygos system on this side.

From its formation beside the upper thoracic vertebrae, the vein turns forwards and upwards across the left side of the arch of the aorta. On the arch it passes between two nerves: the left phrenic nerve lies superficial to it, on its lateral side, while the left vagus nerve lies deep to it, medially. It then ends by opening into the left brachiocephalic vein behind the manubrium.

Small vessels may join it along the way, including left bronchial veins and, in some people, the left pericardiacophrenic vein. Below, it commonly has a connection with the accessory hemiazygos vein, so the upper left intercostal spaces can drain either upwards into the brachiocephalic vein or downwards into the azygos system.

On a frontal chest radiograph the end of this vein, seen end-on beside the aortic knuckle, sometimes produces a small rounded bump called the aortic nipple. It should not be mistaken for a lymph node or mass. The vein may enlarge when it carries collateral flow, for example when the superior vena cava or left brachiocephalic vein is obstructed. The vein is also a landmark in surgery on the aortic arch and for the course of the left vagus and phrenic nerves.

Course and drainage

Begins at

Formed by the left posterior intercostal veins of the second, third and often fourth spaces.

Drains into

Crosses the left side of the aortic arch to open into the left brachiocephalic vein.

Drains

Drains the upper left intercostal spaces and may receive left bronchial veins.