This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The renal arteries come off opposite the first lumbar vertebra. The right one, a little the longer and higher, passes out beneath the vena cava, head of the pancreas, and second portion of the duodenum. The left one passes behind the pancreas. On reaching the kidney they break into three or four (sometimes more) branches. One of these branches usually proceeds down and enters the kidney on the lower posterior side of the pelvis. The other branches enter anteriorly. The renal vein on leaving the kidney is formed by several branches which pass either in front or posterior to the arterial branches. Greig Smith held ("Abdominal Surgery," vol. ii., p. 799) that the veins were posterior to the arteries. The pelvis is posterior; hence in searching for stone if it is desired to open the pelvis of the kidney it should be incised posteriorly. The usually accepted order is, pelvis posterior, then the arteries, and lastly the veins most anterior (Fig. 434). The blood-vessels of the anterior portion pass out toward the cortex and on passing its middle encroach a little on the posterior side. For this reason incisions through the kidney substance are made on its convex border about 1 cm. (2/5 in.) posterior to its middle (Fig. 435).
View of inner edge.
Fig. 434. - The right kidney, showing the relations of the pelvis and blood-vessels.
There are two capsules of the kidney - a fibrous one and a fatty one. The fibrous capsule covers the outside of the kidney and is prolonged into the hilum and lines the sinus. It can be stripped from the kidney, but when the organ is diseased it brings small portions of the kidney substance with it. The fatty capsule surrounds the kidney, being more abundant around its edges and not so much on its anterior and posterior surfaces. The kidney lies comparatively loose in this fatty capsule, slipping backward and forward. The fatty capsule is continuous below with the subperitoneal fat.
Covering the fatty capsule is the perirenal fascia, composed of two layers - anterior and posterior. The anterior is continuous with that of the opposite side over the vertebral column. It proceeds outward over the vessels, ureter, and kidney, and fatty capsule, blending at the outer and upper border with the posterior layer; below, it fades away in the subperitoneal tissue of the iliac fossa. The posterior layer passes inward behind the kidney from its outer and upper borders, to be attached to the sides of the vertebral column. Above, these layers are attached to the diaphragm; below, they are continuous with the subperitoneal tissue of the iliac fossa. There is also some perirenal fat behind the perirenal fascia, between it and the muscles beneath (Fig. 436).