Each kidney receives arterial blood supply from its corresponding renal artery, and it is drained by its corresponding renal vein.

Arterial blood supply

Each kidney is supplied by a single large renal artery, which is a lateral branch of the abdominal aorta. The renal arteries usually arise at the level between the L1 and L2 vertebrae, just inferior to the origin of the superior mesenteric artery.

The left renal artery typically arises a bit higher than the right. In contrast, the right renal artery is longer and travels posterior to the inferior vena cava. Upon reaching the hilum, each renal artery divides into anterior and posterior branches, which supply the renal parenchyma.

Additionally, it is common for kidneys to have accessory renal arteries. They originate from the lateral aspect of the abdominal aorta above or below the primary renal arteries. The accessory renal arteries enter the hilum together with the primary arteries or pass directly into the kidney somewhere else except the hilum. This type of accessory renal arteries is called the extrahilar arteries.

Venous drainage

Multiple veins from the renal hilum merge and form the left renal vein and right renal vein. The renal veins are located anterior to the renal arteries, and they are the most anterior structures within the renal hilum.

Both renal veins drain into the inferior vena cava, which further carries venous blood back to the heart. On its way to the inferior vena cava, the left renal vein collects the left suprarenal vein, while the right suprarenal vein directly flows into the inferior vena cava.

Additionally, the left renal vein is longer than the right one. It passes anterior to the abdominal aorta and posterior to the superior mesenteric artery. It is important because an aneurysm (bulging) of either of these two vessels can compress the left renal vein.

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Blood supply of kidneys