Anatomy

The kidneys are situated in the retroperitoneum and lie between the upper border of the twelfth thoracic and third lumbar vertebrae. Each kidney has a convex lateral border and a concave medial border which merge at the poles (superior and inferior portions). Surrounding each organ is the fibrous renal capsule, which is loosely adherent to it. Adipose tissue (peri-renal fat) encases the capsule and is in turn surrounded by the Gerota's fascia, which secures the kidney to the posterior abdominal wall. Much of the medial border comprises an indentation - the hilum -through which the renal vessels, nerves, lymphatics and the renal pelvis enter or leave the renal sinus, the space enclosed by the renal parenchyma. The right kidney is usually slightly lower than the left on account of the liver. Each kidney is about 11-12 cm in length, 5-7.5 cm in breadth, and 2.5-3.5cm in thickness and weighs between 115 and 175 g (Figure 28.1). The persistence of distinct fetal lobes is common and is a normal anatomical variant.

Lymph Nodes

Renal calyces

Figure 28.1. Anatomy of the kidney. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

Renal calyces

Figure 28.1. Anatomy of the kidney. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

Pictures Malignant Lymph Lodes

Figure 28.2. Kidney - regional lymph nodes. The regional lymph nodes are the hilar, abdominal para-aortic and paracaval nodes. Laterality does not affect the N categories. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

Figure 28.2. Kidney - regional lymph nodes. The regional lymph nodes are the hilar, abdominal para-aortic and paracaval nodes. Laterality does not affect the N categories. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

The relative position of the main structures in the hilum is generally as follows: the vein is in front, the artery in the middle, and the ureter behind and directed downwards. The renal capsule is easily stripped off revealing a smooth and even surface. The parenchyma consists of cortex and medulla that are grossly distinct. The cortex forms a 1 cm layer beneath the renal capsule and extends down between the renal pyramids forming the columns of Bertin. The medulla consists of renal pyramids and is divided into an outer medulla and inner medulla or papilla. The papilla protrudes into the minor calyx. Its tip has between 20 and 70 openings of the papillary collecting ducts (Bellini's ducts).

The renal pelvis is the sac-like expansion of the upper ureter. Two or three major calyces extend from the pelvis and divide into minor calyces, into which the papillae protrude. The ureters measure approximately 30 cm in length equally divided between retroperitoneum and pelvis. They are usually placed on a level with the spinous process of the first lumbar vertebra and run downwards and medially in front of the psoas major and, entering the pelvis, reach the lateral angle of the bladder. Finally, the ureters run obliquely for about 2 cm through the wall of the bladder and open by slit-like apertures into the cavity at the lateral angles of the trigone. Owing to their oblique course, the upper and lower walls of the terminal portions of the ureters become closely applied to each other when the bladder is distended, and, acting as valves, prevent regurgitation of urine from the bladder.

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