Anatomy of the renal vasculature. Which one is TRUE?a. The posterior segmental artery is formed after entering the renal hilum
Roughly a quarter of the cardiac output is supplied to the kidneys via the paired renal arteries. They branch from the aorta at the level of L2 just below the origins of the superior mesenteric (SMA) and adrenal arteries. The right artery passes behind the inferior vena cava (IVC) first, in contrast to the left, which passes almost directly to the kidney. Before entering the hilum, each artery initially gives off a single posterior segmental branch that passes behind the renal pelvis to supply the posterior aspect of the kidney. It can cause obstruction of the pelvi-ureteric junction if it passes in front of the ureter. After entering the hilum, the artery commonly divides into four anterior segmental branches (apical, upper, middle and lower). The divisions and blood supply of the anterior and posterior segmental arteries give rise to a longitudinal avascular plane, known as Brodel’s line, 1–2 cm posterior to convex border of the kidney. Segmental arteries give rise to lobar arteries within the renal sinus, which become interlobar arteries that lie in between the Columns of Bertin in the parenchyma. These give off arcuate branches, which become the interlobular arteries that eventually form the afferent arteries of the glomeruli. The renal vein lies in front of the artery in the renal hilum. The right vein is 2–4 cm in length in comparison to the left, which may be up to 10 cm. The left renal vein reaches the IVC by passing behind the SMA and in most cases in front of the aorta.