The lumbar veins are four pairs of blood vessels that drain the lumbar segments of the spinal cord, posterolateral abdominal wall and lumbar structures of the back. They usually empty into the inferior vena cava, but they can also drain into the ascending lumbar, azygos, renal or other lumbar veins.
Ipsilateral lumbar veins are interconnected by ascending lumbar veins, one on each side of the body. On their way towards the inferior vena cava, the lumbar veins receive many tributaries from the posterolateral abdominal wall. This establishes an alternate pathway for the drainage of the pelvis, spinal cord and lower limbs in case of an inferior vena cava obstruction.
|Drains from||Lumbar part of sympathetic chain, skin and muscles of posterolateral abdominal wall, joints of the lumbar spine, lumbar portion of the deep back muscles, lower two-thirds of spinal cord|
|Tributaries||Epigastric, superficial epigastric, circumflex iliac and lateral thoracic veins; internal and external vertebral venous plexuses|
|Drains to||Inferior vena cava (occasionally ascending lumbar, azygos, renal, other lumbar veins)|
|Drainage area||Lumbar segments and structures of the spinal cord and back
Posterolateral abdominal wall
This article will discuss the anatomy and function of the lumbar veins.
Anatomy and course
The four pairs of lumbar veins begin their course by arising from small venules that drain the skin and muscles of the posterolateral abdominal wall. They travel posteriorly along the posterolateral abdominal wall, alongside the corresponding lumbar arteries. Along the way, they receive tributaries from superficial veins of the anterolateral trunk; epigastric (superior, inferior), superficial epigastric, lateral thoracic and circumflex iliac veins.
As the lumbar veins continue along the wall of the posterior trunk, they usually pass posterior, or occasionally anterior to the lumbar part of the sympathetic trunk. Here, each lumbar vein drains blood from the sympathetic trunk and the lumbar portion of the deep back muscles.
Next, the lumbar veins continue towards the lumbar vertebrae. Anterior to the transverse processes of the lumbar vertebrae, the lumbar veins interconnect via two longitudinal vessels called ascending lumbar veins. There are two in total, one right and one left, corresponding to the right and left lumbar veins, respectively. Each ascending lumbar vein courses medially to the psoas major muscle and interconnects the ipsilateral lumbar, iliolumbar and common iliac veins. The ascending lumbar veins unite with the corresponding subcostal veins to form the azygos vein on the right and hemiazygos vein on the left. Occasionally, the ascending lumbar veins might drain into the first lumbar veins.
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The lumbar veins continue anteriorly along the anterolateral surfaces of the lumbar vertebral bodies. Here, they receive blood from the internal and external vertebral venous plexuses, draining the inferior two-thirds of the spinal cord. The lumbar veins also receive blood from the joints of the lumbar spine. From this point onwards, the trajectory of the lumbar veins can vary slightly. The third and fourth lumbar veins are constant and drain into the inferior vena cava. The left pairs are longer because they travel posterior to the abdominal aorta before reaching the inferior vena cava. In contrast, the first and second lumbar veins are quite variable. They can drain into several blood vessels, including the inferior vena cava, ascending lumbar veins, lumbar azygos veins or renal veins. The first and second lumbar veins can even empty into inferior lumbar veins.
Learn more details about the anatomy of the trunk veins, including the lumbar veins, using the resources provided in the following study unit: