Urology>>>>>Anatomy & Embryology
Question 7#

Anatomy of the kidneys. Which one of the following is TRUE?

A. The left kidney lies between L1 and L3
B. The dromedary hump on the medial aspect of the kidney is more common on the right
C. The lower pole of the kidney is more medial and posterior than the upper pole
D. Gerota’s fascia surrounds the kidney except medially where there is a potential open space
E. The main lymphatic drainage from the left kidney is into the lateral paraaortic nodes

Correct Answer is E

Comment:

Answer E

Each kidney measures 10–12 cm in length and weighs between 135 and 150 g. The right kidney is shorter and wider than the left and lies between the levels of the L1–L3 vertebrae from displacement by the liver. The left kidney lies up to 2 cm higher between T12 and L3. The dromedary hump is a bulge on the lateral contour of the kidney, more common on the left, caused by downward pressure from either the liver or spleen and is of no clinical significance. Each kidney is orientated in such a way that the upper poles are more medially and posteriorly located than the lower poles. Much of the surrounding relationship of each kidney is similar. The posterior upper third is covered by the diaphragm, the medial lower two-thirds lie against the psoas and the lateral contours are in contact with quadratus lumborum and the aponeurosis of transversus abdominis. Additionally, on the right, much of the medial aspect lies opposite the descending duodenum and the hepatic flexure of the colon cross over the anterior surface of the lower pole. On the left, the pancreatic tail reaches the upper pole and above this is the posterior gastric wall. The spleen is found on the outer upper aspect and is attached to the kidney by the splenorenal ligament. The splenic vessels lie adjacent to the hilum and the splenic flexure of the colon lies anterior to the lower pole. Gerota’s fascia surrounds the kidney except inferiorly. Each kidney is divided into an outer thinner cortex and deeper thicker medulla. The medulla typically contains 7–9 renal pyramids whose apex (renal papillae) point towards the renal pelvis. Each papillae is cupped by a minor calyx and each drains via an infundibulum into two or three major calyces. These coalesce to form the renal pelvis that gives rise to the ureter. The cortex extends between the pyramids as columns of Bertin that contain the branching renal vasculature. Closely associated with these blood vessels are lymphatics that empty into larger trunks in the renal sinus before eventually reaching the lymph nodes closely associated with the renal veins. On the left, the lymphatic drainage is mainly to the lateral paraaortic nodes whilst on the right it is to the interaortocaval and paracaval nodes. The autonomic supply to the kidney is mainly concerned with vasomotor control; the sympathetic fibres originate from spinal nerves T8 to L1 and cause vasoconstriction whilst the vagal parasympathetic fibres cause vasodilation.