Left subcostal vein

At a glance

English

Left subcostal vein

Latin (TA2)

Vena subcostalis sinistra

System

Vein

Region

Trunk

Side

Single, on the midline

About the left subcostal vein

The left subcostal vein is the lowest member of the series of segmental veins that follow the ribs. It lies below the twelfth rib rather than between two ribs, so it is called subcostal rather than intercostal, but in every other way it behaves like a posterior intercostal vein.

It drains the tissues of the upper posterior and lateral abdominal wall below the last rib, the muscles and skin of that band of the body wall, and receives small tributaries from the vertebral region. It runs with the subcostal artery, a branch of the thoracic aorta, and with the subcostal nerve, the anterior ramus of the twelfth thoracic spinal nerve. As in the intercostal spaces the vein is usually the highest of the three, with the artery and then the nerve below it.

Traced medially, the vein passes behind the lateral arcuate ligament and onto the side of the twelfth thoracic vertebra. There it unites with the left ascending lumbar vein, which has climbed from the lumbar region, and the vessel formed is the hemiazygos vein. The hemiazygos ascends on the left of the vertebral bodies before crossing behind the aorta to the azygos vein.

Because it is one of the roots of the hemiazygos vein, the subcostal vein is part of the collateral pathway that opens up between the inferior and superior venae cavae when the inferior vena cava is obstructed. It may be met in surgery on the kidney or the upper lumbar spine through the loin, since it runs close to the lower border of the twelfth rib.

Course and drainage

Begins at

Begins in the tissues of the posterior and lateral abdominal wall below the left twelfth rib.

Drains into

Joins the left ascending lumbar vein beside the twelfth thoracic vertebra to form the hemiazygos vein.

Drains

Drains the band of body wall below the last rib on the left.