Bean-shaped organs about 11 cm long on the back wall of the abdomen, the right lying lower because of the liver
Kidney — right lower than left by about 1 to 2 cm.
Anatomy · Organs & viscera
Kidney
Bean-shaped, retroperitoneal, T12 to L3
Posterior abdomen · urinary system
The kidneys are a pair of bean-shaped organs, each about the size of a fist, lying on either side of the spine against the back wall of the abdomen, behind the peritoneum. They span roughly T12 to L3, partly sheltered by the 11th and 12th ribs, and the right sits a little lower than the left because of the liver. Each has a hilum facing inwards, where the renal vein, artery and pelvis leave and enter, with an adrenal gland on its upper pole.
How to spot them
- ▸A pair of smooth, dark-red, bean-shaped organs on the posterior abdominal wall either side of the spine, in the fat of the loin
- ▸A notch called the hilum faces medially; from front to back the structures at the hilum are the vein, the artery and the pelvis
- ▸Inside, a pale outer cortex, an inner medulla of triangular pyramids, and a funnel-shaped renal pelvis
- ▸Wrapped in a fibrous capsule, then perinephric fat, then renal fascia (Gerota's fascia)
What to know
At its medial notch, the structures from front to back are the vein, the artery and the pelvis
The hilum of the kidney: vein, artery, pelvis.
Wrapped in fat and an envelope named after a Romanian anatomist, Dimitrie Gerota
Gerota's fascia (renal fascia) around the kidney.
Triangular masses of striped tissue with their tips pointing into cup-like spaces
The renal pyramids of the kidney, draining into the calyces.
Extensions of cortex that dip between the pyramids, named after a French anatomist
The renal columns (of Bertin) in the kidney.
Lies on the diaphragm, psoas major and quadratus lumborum, partly shielded by the 11th and 12th ribs
The kidney's posterior relations — a stab at the loin below the 12th rib may reach it.
In front of the right one lie the liver, duodenum and hepatic flexure; in front of the left, the stomach, spleen and pancreatic tail
The anterior relations of the right and left kidneys.
Fused at the lower poles in about 1 in 500 people, and caught under the inferior mesenteric artery
Horseshoe kidney.
Key ideas
- Because they lie behind the peritoneum, the kidneys are approached from the loin, and pain from a stone typically radiates from the loin to the groin.
- Blood comes straight from the aorta by short renal arteries; the kidneys receive around a fifth of cardiac output, which passes through the cortex first.
Quick-fire facts
- •Each kidney is about 11 cm long, 6 cm wide and 3 cm thick, and weighs about 150 g.
- •The left kidney lies at about T12 to L3 and the right about 1 to 2 cm lower; the hilum lies at about L1 (transpyloric plane).
- •The hilum contains, from front to back, the renal vein, the renal artery and the renal pelvis (VAP).
- •The right renal artery is longer and passes behind the inferior vena cava; the left renal vein is longer and passes in front of the aorta, below the superior mesenteric artery.
- •The kidney has about 8 to 18 pyramids (often about 8 to 12), each draining into a minor calyx; minor calyces join into major calyces and the renal pelvis.
- •The perinephric fat and renal fascia hold it in place; loss of fat can make it slip (nephroptosis).
- •Each kidney is capped by an adrenal gland, which is enclosed in the same fascia but lies above it, not inside the capsule.
- •Living kidney donation works because a person can live well with one kidney.
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Sources
- TeachMeAnatomy — The Kidney
- OpenStax — Gross Anatomy of Urine Transport (Anatomy and Physiology 2e, section 25.2)