Topography and fascial spaces
The kidneys are located in the retroperitoneal space, specifically within the perirenal space (perirenal space). This space is bounded by a thin layer of connective tissue, Gerota fascia (Gerota fascia). Gerota fascia sometimes divides into the posterior Zuckerkandl fascia and the lateroconal fascia. It closely adheres to the adrenal glands superiorly and encloses the renal pedicle (vessels, lymphatic and collecting systems).
Thin connective tissue septa, Kümin's septa, run through the perirenal space. In pathological processes (e.g., inflammation), they may thicken, appearing on scans as perinephric stranding (perinephric stranding). The perirenal spaces communicate with each other, with the retroperitoneal vascular compartment, and with the bare area of the liver.
Vascular anatomy
The topography of the elements of the renal pedicle from anterior to posterior follows a strict rule: renal veins (v. renalis) are located anteriorly, renal arteries (a. renalis) lie behind them, and renal pelves (pelvis renalis) are posterior to all.
Venous drainage has specific features: ipsilateral adrenal and gonadal veins may drain into the anterior and posterior branches of the renal vein, which is a normal variant. Among incidental findings on MRI or CT, a retroaortic left renal vein is not uncommon. Arterial blood supply is also variable: accessory (duplicate) renal arteries are frequently identified.
Collecting system
The collecting system of the kidney begins with 10–14 concave minor calyces (minor calyces). They are bounded at the edges by forniceal angles (forniceal angles). Minor calyces merge to form upper, middle, and lower major calyces (major calyces), which continue into the renal pelvis (renal pelvis).
The renal pelvis may lie entirely within the renal sinus or partially protrude beyond its borders (extrarenal pelvis). With age, renal atrophy, or steroid use, adipose tissue may proliferate within the renal sinus—a condition known as renal sinus lipomatosis.
Ureters and urinary bladder
The ureters (ureters) have three physiological constrictions: at the ureteropelvic junction, at the crossing of the iliac vessels, and at the entrance to the lesser pelvis. On radiographs, they project along the anterior surface of the psoas major muscle, and the distance between them at the L3 vertebral level should exceed 5 cm.
The urinary bladder consists of a peritoneum-covered apex, base, neck, and inferolateral surfaces. An important landmark is the trigone of the bladder, bounded by the ureteric orifices and the internal urethral orifice. Urine outflow from the bladder in males occurs through the urethra, in the posterior part of which (prostatic part) the seminal colliculus and prostatic utricle (remnant of the Müllerian duct) are located.
Briefly: answers to topical questions
Which branches arise from the renal artery before it enters the renal hilum?
Before entering the renal hilum, the renal artery gives off branches heading superiorly and inferiorly to adjacent structures. These include:
- Inferior suprarenal arteries (aa. suprarenales inferiores) — thin vessels running superiorly.
- Ureteric branches (rr. ureterici) — vessels heading inferiorly.
What anatomical segments does the kidney consist of?
The kidney consists of five anatomical segments formed by the branching of the anterior and posterior divisions of the renal artery. The following segments are distinguished:
- Superior (a. segmenti superioris) — supplied by the anterior division.
- Anterior superior (a. segmenti anterioris superioris) — supplied by the anterior division.
- Anterior inferior (a. segmenti anterioris inferioris) — supplied by the anterior division.
- Inferior (a. segmenti inferioris) — supplied by the anterior division.
- Posterior (a. segmenti posterioris) — supplied by the posterior division.
Which organs are related to the anterior surface of the right kidney?
The anterior surface of the right kidney is related to abdominal organs, separated from it by the prerenal fascia (fascia prerenalis) and loose connective tissue. These include:
- Liver — related to the superior pole.
- Colon — the right colic flexure is related laterally.
- Duodenum — the descending part is related to the hilum and medial margin.
What are the normal dimensions of the kidney (length, width, thickness) according to ultrasound in adults?
The normal length of the kidney in adults is 12–14 cm, while the difference in length between the right and left kidney should not exceed 2 cm. Ultrasound tends to underestimate organ length. Information on the normal width and thickness of the kidney is not provided in the sources.
To memorize the arrangement of the renal pedicle elements from anterior to posterior, use the rule V-A-P: Vein — Artery — Pelvis.
Class and exam questions
What is fetal lobulation of the kidney?
This is an irregular, lobular contour of the kidney at the junction of the renal lobes. Normally, it is clearly visible in children under 5 years of age. If it persists in adults, it is considered a normal variant.
What does the perirenal space communicate with?
The perirenal spaces communicate with each other along the midline, with the retroperitoneal vascular space, and with the bare area of the liver.
How does inflammation in the perirenal tissue appear on CT?
Inflammation is manifested by thickening of perinephric stranding, a radiological symptom known as "Kumin's septa thickening".
What else to study on this topic
- MRI anatomy of retroperitoneal vessels and their structural variants (e.g., circumaortic left renal vein)
- Radiological signs of cloacal exstrophy and associated pathologies on voiding cystourethrography
- Anatomical constrictions of the ureters as sites of typical calculus obstruction
- Histological structure of various sections of the male urethra and urinary bladder
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