After entering the hilum, the renal artery ramifies
to form interlobar arteries, which run between the medullary pyramids.
At the corticomedullary junction, the interlobar arteries give rise to
arcuate arteries, which run parallel to the surface of the kidney. The
interlobular arteries, derived from the arcuate arteries, run between
the medullary rays toward the capsule. The interlobular arteries branch
into several afferent glomerular arterioles, which supply the
capillaries of the glomeruli. From there blood passes into the efferent
glomerular arterioles, which branch again to form a second capillary
network, supplying the majority of other portions of the same nephrons.
The blood is collected into the interlobular veins, which join the
arcuate veins. Then blood flows into the interlobar veins, which
collectively form the renal vein through which blood leaves the kidney.