What is the blood supply to the lumbosacral (lower back and sacral) plexus?

From the Guidelines

The blood supply to the lumbosacral plexus primarily comes from the lumbar and iliolumbar arteries, branches of the abdominal aorta, and the lateral sacral arteries, which branch from the internal iliac artery. The lumbar portion of the plexus (L1-L4) receives its blood supply from the lumbar arteries, which arise from the posterior aspect of the abdominal aorta 1. Each lumbar artery divides into anterior and posterior branches, with the posterior branches supplying the vertebral bodies, spinal cord, and adjacent nerve roots of the lumbar plexus. The iliolumbar artery, a branch of the internal iliac artery, also contributes to the blood supply of the lower lumbar plexus. The sacral portion of the plexus (L5-S4) is primarily supplied by the lateral sacral arteries, which are branches of the internal iliac artery 1. These vessels provide crucial oxygenation and nutrients to the nerve fibers that form the major nerves of the lower extremity, including the femoral, obturator, and sciatic nerves. Adequate blood supply is essential for proper nerve function, and compromised blood flow to this region can result in neurological symptoms affecting the lower limbs. Some key points to consider when evaluating the blood supply to the lumbosacral plexus include:

• The lumbar arteries arise from the posterior aspect of the abdominal aorta and supply the lumbar portion of the plexus
• The iliolumbar artery contributes to the blood supply of the lower lumbar plexus
• The lateral sacral arteries supply the sacral portion of the plexus
• Compromised blood flow to this region can result in neurological symptoms affecting the lower limbs, as noted in studies on plexopathy 1.

From the Research

Blood Supply to the Lumbosacral Plexus

The blood supply to the lumbosacral plexus is provided by various arteries, including the iliolumbar artery. The following points highlight the key aspects of the blood supply:

• The iliolumbar artery originates from the posterior trunk of the internal iliac artery in most cases, but its origin can vary, arising from the common iliac artery, external iliac artery, or internal iliac artery 2.
• The iliolumbar artery supplies the lumbosacral plexus and surrounding structures, including the ilium, psoas muscle, and lumbar spine 3, 4.
• The arterial supply to the lower lumbar spine, including the lumbosacral region, is provided by segmental arteries and the iliolumbar artery 5.
• The segmental arteries run from the vertebra through the lamina, while the iliolumbar artery is distributed around the inferior articular process through the lamina 5.
• There are variations in the arterial supply to the lower lumbar spine, with different combination patterns of arteries observed in approximately 50% of patients 5.

Neurovascular Relationships

The neurovascular relationships of the lumbosacral plexus are complex, with several structures in close proximity:

• The S2 alar-iliac screw placement has significant regional neurovascular structures along its path, including the obturator nerve, lumbosacral trunk, sacral plexus, and iliac vein and artery 6.
• The iliolumbar artery passes anterior to the obturator nerve in 70% of cases and posterior to the obturator nerve in 30% of cases 4.
• The iliolumbar vein lies anterior to the obturator nerve in 45% of cases and posterior in 55% of cases 4.
• The anatomical features of the iliolumbar artery and vein, and their correlation with surrounding structures, are essential for decreasing iatrogenic trauma to neurovascular structures in the iliolumbar region 4, 2.