Lumbar veins

At a glance

English

Lumbar veins

Latin (TA2)

Venae lumbales

System

Vein

Region

Trunk

Side

Paired, left and right

About the lumbar veins

The lumbar veins drain the back and side walls of the abdomen, the lumbar muscles and the lumbar part of the vertebral column. They are the abdominal counterparts of the posterior intercostal veins in the chest. There are usually four on each side, accompanying the four pairs of lumbar arteries around the bodies of the first to fourth lumbar vertebrae. As in the intercostal spaces, each vein lies just above its artery.

Each vein starts with a dorsal tributary from the muscles and skin of the back and an abdominal tributary from the abdominal wall. Near the spine it receives branches from the vertebral venous plexuses, including veins from the front of the spinal canal. Running forwards and medially along the vertebral body, each vein passes deep to psoas major and behind the sympathetic trunk.

The lumbar veins are linked by a vertical channel, the ascending lumbar vein, which runs in front of the transverse processes behind psoas. The upper two lumbar veins usually end in this channel rather than in the cava. Above, the ascending lumbar vein meets the subcostal vein and continues as the azygos (right) or hemi-azygos (left). The lower two normally open into the back of the cava. On the left they must pass behind the aorta to get there, while on the right they have a shorter path. The pattern varies: any lumbar vein may favour the ascending lumbar or caval route, and a left lumbar vein may end in the left renal vein.

Because they connect the inferior vena cava with the azygos and vertebral systems, the lumbar veins offer a bypass if the cava is blocked. They are also a nuisance in practice: catheters passed up the cava can slip into a lumbar vein and need repositioning, and during anterior spinal surgery or aortic surgery the lumbar veins must be identified and controlled, as they are short and bleed freely.

Course and drainage

Begins at

Formed beside the lumbar vertebrae from dorsal and abdominal tributaries of the posterior abdominal wall and back, with branches from the vertebral venous plexuses.

Drains into

The upper veins usually end in the ascending lumbar vein; the lower two open into the back of the cava.

Drains

Drain the posterior and lateral abdominal wall, the lumbar back muscles, the lumbar vertebrae and what lies in the lumbar spinal canal.