Kidneys, Ureters & Suprarenals

What are the parts and functions of the urinary system?

• Parts: Kidneys, ureters, urinary bladder, urethra.

• Functions:

  • Filtration of blood & formation of urine.

  • Waste excretion.

  • Fluid & electrolyte balance → body fluid volume & blood pressure.

  • Acid‑base balance.

  • Hormone formation & release: Renin (BP), Erythropoietin (RBC production), Calcitriol (Ca²⁺ balance).

Where are the kidneys, ureters, and suprarenals located?

• Kidneys: bean‑shaped, retroperitoneal, posterior abdominal region, lateral to vertebral column.

• Extent: T12–L3 in supine position.

• Right kidney lower than left.

• Ureters: run inferiorly, cross pelvic brim at common iliac bifurcation.

• Suprarenals: associated with superior pole of each kidney.

What are the surfaces, poles, and borders of each kidney?

• 2 surfaces: anterior, posterior.

• 2 poles: superior, inferior.

• 2 borders: medial, lateral.

• Hilum (medial indentation): transmits renal vein, renal artery, ureter (VAU), plus lymphatics & nerve plexuses.

• Hilum continuous with renal sinus → contains renal pelvis.

What structures relate to the anterior surfaces of kidneys?

• Right kidney: right suprarenal, liver, descending duodenum, right colic flexure, small intestine.

• Left kidney: left suprarenal, stomach, spleen, pancreas, left colic flexure, descending colon, jejunum.

: What structures relate to posterior surfaces of kidneys?

• Diaphragm superiorly.

• Psoas major, quadratus lumborum, transversus abdominis inferiorly.

• Subcostal nerves/vessels, iliohypogastric & ilioinguinal nerves.

• Left kidney anterior to ribs 11 & 12; right kidney anterior to rib 12 only.

• Pleural sacs & costodiaphragmatic recesses lie posterior.

What are the coverings of the kidneys?

• Perirenal fat: covers fibrous capsule & adrenal glands.

• Fibrous capsule: closely applied to kidney surface.

• Renal fascia (Gerota): condensation of extraperitoneal connective tissue enclosing perirenal fat; encloses kidneys & suprarenals (separated by septum).

• Fascia incised during surgery.

How is renal fascia continuous with surrounding structures?

• Superiorly: diaphragm.

• Laterally: fascia transversalis.

• Medially: anterior layer continuous with renal vessel sheaths, aorta, IVC; posterior layer blends with psoas fascia.

• Inferiorly: encloses ureter, directs infection inferiorly into pelvis.

• Pararenal fat: external to fascia, part of retroperitoneal fat.

What are the cortex and medulla features?

• Cortex: outer layer.

• Medulla: inner, divided by renal columns into pyramids.

• Pyramid bases face cortex; apices (papillae) project into renal sinus, surrounded by minor calyx.

How do calyces and pelvis form?

• Minor calyces unite → major calyces.

• 2–3 major calyces unite → renal pelvis, funnel‑shaped superior ureter.

What structures are in cortex vs medulla?

• Cortex: renal corpuscles (glomerulus + Bowman’s), proximal parts of PCT/DCT, collecting ducts.

• Medulla: thick/thin limbs of Henle, distal parts of PCT/DCT, distal collecting ducts.

Describe renal arterial supply.

• Renal artery: branch of abdominal aorta, arises below SMA (Superior Mesenteric Artery) (L1–L2).

• Right renal artery longer, passes behind IVC.

• Accessory renal arteries common, may enter hilum or extra‑hilar.

Describe renal venous drainage.

• Multiple veins unite → left & right renal veins.

• Lie anterior to arteries at hilum, drain into IVC.

• Left renal vein longer, crosses midline between aorta & SMA → can be compressed (nutcracker syndrome).

How are kidneys segmented by arteries?

• Renal artery → anterior & posterior branches → 5 segmental end arteries (no anastomosis).

• Segments: superior, inferior, posterior, anterosuperior, anteroinferior.

• Pathway: lobar → interlobar → arcuate → interlobular → afferent arterioles → glomerulus → efferent → peritubular capillaries (cortex) or vasa recta (medulla).

What are features of vasa recta?

• Descending portion: arterial, small diameter, continuous endothelium.

• Ascending portion: venous, larger diameter, thin fenestrated walls.

• Ascending drains → interlobular vein → arcuate → interlobar → renal vein.

Why are segmental arteries clinically important?

• End arteries, no collateral circulation.

• Occlusion → infarction of segment.

• Infarct may be silent or cause pain, CVA tenderness, hematuria.

• Allows surgical resection of segment without affecting others.

What is renal vein entrapment syndrome?

• Left renal vein compressed between SMA & aorta.

• Causes left flank pain, hematuria.

• Males: varicocele, left testicular pain.

• Differs from SMA syndrome (duodenum compression).

Describe ureters.

• 25–30 cm muscular tubes connecting kidneys to bladder.

• Upper half: abdomen, retroperitoneum, medial to psoas major.

• At pelvic brim: cross common iliac or external iliac artery.

• Enter bladder in pelvic cavity.

• Adhere to peritoneum → risk during mobilization.

What are sites of ureteric constriction?

• Ureteropelvic junction (renal pelvis → ureter).

• Crossing pelvic brim/common iliac bifurcation.

• Ureterovesical junction (pierces bladder wall obliquely).

• Clinical: sites for stone impaction.

1. Ureteropelvic junction: Where the renal pelvis narrows as it transitions into the ureter.

2. Crossing pelvic brim/common iliac bifurcation: The point where the ureter passes over the iliac vessels and enters the true pelvis.

3. Ureterovesical junction: Where the ureter obliquely pierces the muscular wall of the bladder. 

What are features of renal calculi?urinary tract stones

• More common in men (20–60 years), associated with sedentary lifestyle.

• Symptoms: severe intermittent pain (ureteric colic) felt from loin to groin, proximal anterior thigh, or external genitalia (T11–L2 dermatomes).

• May present with hematuria.

• Lithotripsy: shock waves break stones into fragments that pass in urine.

What is a staghorn calculus?

• Large stone forming a cast of the renal pelvis and calyces.

• Resembles horns of a stag (coral calculi).

What is the blood supply of the ureter?

• Arteries:

  • Upper: renal artery branches.

  • Middle: testicular/ovarian arteries, abdominal aorta, common iliac arteries.

  • Pelvic: internal iliac artery branches.

  • Anastomose longitudinally.

• Veins:

  • Upper: renal vein.

  • Middle: gonadal vein.

  • Pelvic: internal iliac veins.

What is lymph drainage of kidneys and ureters?

• Kidneys: paraaortic (lateral aortic/lumbar) nodes at renal artery origin.

• Ureters:

  • Upper: paraaortic nodes.

  • Middle: common iliac nodes.

  • Inferior: external/internal iliac nodes.

What is the nerve supply of kidneys and ureters?

• Sympathetic: kidneys T10–T12; ureters T11–L2.

• Parasympathetic: kidneys vagus; ureters vagus & S2–S4.

• Fibers pass via renal/hypogastric plexuses along vessels.

• Pain referral: T11–L2 dermatomes → posterior/lateral abdominal wall, pubic region, scrotum/labia majora, proximal anterior thigh (“loin to groin”).

What are features of renal cell carcinoma?

• Grow outward into fat & fascia.

• Symptoms: hematuria, loin pain, palpable mass.

• Invade renal vein → spread to IVC, right atrium, across tricuspid valve into pulmonary artery.

What are features of renal transplant?

• Began in US in 1950s; rejection was major issue initially.

• Common procedure for end‑stage renal disease.

• Iliac fossa is ideal site: creates new space without compromising other structures.

• Extraperitoneal approach → faster recovery.

What are features of suprarenal glands?

• Size: 3–5 cm transverse, weight ~5 g.

• Color: yellowish‑orange.

• Location: superior pole of each kidney, embedded in perirenal fat/fascia, separated by septum.

• Cortex + medulla.

• Renal fascia attaches to diaphragm crura.

How do right and left suprarenal glands differ?

• Right: pyramidal, behind right liver lobe & IVC, anterior to right diaphragm dome.

• Left: semilunar, related to stomach, spleen, pancreas, left diaphragm dome.

What is the blood supply of suprarenal glands?

• Arteries:

  • Superior suprarenal (from inferior phrenic).

  • Middle suprarenal (from aorta).

  • Inferior suprarenal (from renal artery).

• Veins:

  • Right suprarenal vein → IVC.

  • Left suprarenal vein → left renal vein.

What is the nerve supply of suprarenal glands?

• Primarily sympathetic fibers via greater, lesser, least splanchnic nerves.

• Preganglionic fibers end in adrenal medulla.

• Postganglionic fibers to vessels arise from aortic ganglia.

What imaging techniques are used for kidneys and suprarenals?

• Plain X‑ray abdomen (KUB).

• Intravenous urogram (IVU).

• Ultrasound.

• CT scan.

• Nuclear medicine.