Lumbar arteries

Origin and course

The four lumbar arteries originate from each posterolateral side of the abdominal aorta. If the fifth pair of arteries is present, it arises either from the median sacral artery or iliolumbar arteries.

The lumbar arteries take a posterolateral course over the anterolateral surfaces of the corresponding lumbar vertebrae, passing posterior to the sympathetic trunk and the tendon of psoas major on each side. The right lumbar arteries continue their course, passing posteriorly to the inferior vena cava. The first left lumbar artery passes posterior to the left crus of the diaphragm, while the upper two right lumbar arteries pass posterior to the right crus. Each lumbar artery sends collaterals to anastomose with the lumbar artery one level below and above, respectively. The lumbar arteries on both sides all terminate by anastomosing with the ipsilateral subcostal, posterior intercostal, iliolumbar, deep circumflex iliac and inferior epigastric arteries.

Branches and supply

Each lumbar artery divides into the medial, middle and lateral branch adjacent to the corresponding intervertebral foramen.

• The medial branch gives rise to the spinal (anterior segmental medullary) and ganglionic branches to supply the lumbar segments of the spinal cord and the regional sympathetic ganglia, respectively. The most important spinal branch is the great radicular artery (of Adamkiewicz) which usually arises from the first left lumbar artery. This artery anastomoses with the anterior spinal artery and is the main source of arterial blood to the lower two-thirds of the spinal cord. If this artery gets injured during a thoracoabdominal aortic surgery, it can cause the infarction of the portion of the spinal cord.
• The middle branch gives off the anastomotic and dorsal branches. The dorsal branch takes a posterior course, passing between the transverse processes of lumbar vertebrae and supplies the adjacent deep muscles of the back, joints of the spine and the overlying skin of the back.
• The lateral branch courses over the surface of the posterior abdominal wall; deep to the psoas major and lumbar plexus and over the anterior surface of quadratus lumborum. It passes through the posterior margin of transversus abdominis and continues coursing forwards between the transversus abdominis and internal oblique muscles. Along its course, it gives off the perforating branches that supply the abdominal muscles near which it passes.

Anatomical variations

The great radicular artery (of Adamkiewicz) can sometimes originate from the spinal branch of the last or second to the last posterior intercostal artery, or from the subcostal artery.