Renal artery
Arteria renalis
The renal arteries are paired branches from the sides of the abdominal aorta at about L1–L2, just below the SMA. Together they carry about 20–25% of the cardiac output to the kidneys.
Overview
Course. The right renal artery is longer and passes behind the IVC. The left renal artery is shorter and lies behind the left renal vein, the body of the pancreas and the splenic vein. At the renal hilum the structures are arranged from front to back as vein, artery and renal pelvis.
Segmental branches. Near the hilum each renal artery divides into anterior and posterior divisions. These give five segmental arteries: apical, anterosuperior, anteroinferior, inferior and posterior. They are end arteries, so a blocked branch infarcts a segment of kidney. A relatively bloodless plane between the anterior and posterior territories (Brödel's line) is used for incisions into the kidney.
Within the kidney. The vessels branch in sequence: interlobar, arcuate and cortical radiate (interlobular) arteries, then afferent arterioles, glomeruli, efferent arterioles, and finally peritubular capillaries and vasa recta.
Accessory arteries. Extra (accessory or polar) renal arteries occur in roughly a quarter to a third of people.
Anatomy
- Branches
The inferior suprarenal artery, ureteric branches and the segmental arteries.
Function
- Delivers about 1.1–1.2 L/min of blood for glomerular filtration (renal plasma flow ≈600–650 mL/min).
- Its pressure is sensed by the juxtaglomerular apparatus, which controls renin release.
- Physiology
Renal blood flow is autoregulated, staying nearly constant over a mean arterial pressure range of about 80–180 mmHg. Two mechanisms do this: the myogenic response of the afferent arteriole and tubuloglomerular feedback.
Clinical significance
Renal artery stenosis
In older patients, renal artery stenosis is usually atherosclerotic and affects the ostium and proximal artery. In younger women it is often due to fibromuscular dysplasia, which gives a "string of beads" appearance in the middle and distal artery. Reduced kidney perfusion activates the RAAS, causing renovascular hypertension. Other features are a bruit over the abdomen, sudden ("flash") pulmonary oedema, and acute kidney injury when an ACE inhibitor is started in bilateral disease.
Accessory renal arteries
A lower-pole accessory artery can cross the ureter and obstruct the pelviureteric junction. Accessory arteries also matter for kidney transplantation and kidney surgery.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.