Kidneys and Ureters 27

Stefanella Merola, Ugo Ponticelli, Crescenzo Cacciutto

L. Romano, M. Silva, S. Fulciniti, A. Pinto (eds.) MDCT Anatomy – Body 169 © Springer-Verlag Italia 2011 170 S. Merola et al.

Right Left adrenal gland adrenal gland Upper pole of the kidney Dorsal vertebra a

Inferior vena cava Abdominal aorta Left renal vein Renal sinus

Superior mesenteric artery

Inferior vena cava Abdominal aorta

Left renal vein Right renal vein

Fig. 27.1 a The two kidneys, one on each side of the spine, are located in the retroperitoneum, approximately at the level of vertebrae T12-L3, between the anterior and posterior fascia of Gerota. They are contained within a fatty capsule, with an adrenal gland situated at the top of each one. The asymmetry within the abdominal cavity caused by the presence of the liver typically results in the right kidney being slightly lower than the left, and the left kidney slightly more medial than the right. b The renal artery enters the kidney at the renal hilum, with the renal vein and ureter exiting from this site. The artery is somewhat narrower than the vein. c The renal veins connect the kidney to the inferior vena cava. Since the inferior vena cava is on the right half of the body, the left renal vein is generally longer than the right. The right renal vein is anterior to the right renal artery, while the left renal vein courses between the aorta and superior mesenteric artery to join the inferior vena cava 27 Kidneys and Ureters 171

Liver Upper pole of the right kidney

Colon

Inferior pole of the right kidney

Ileopsoas muscle

Stomach Spleen

Upper pole of Pancreas the left kidney

Inferior pole of the left kidney

Rectus muscle

Fig. 27.2 a Sagittal views along the major axis of the kidney more clearly evidence its anatomical relationships. The anterior surface of the right kidney is related to the inferior surface of the liver and, next to the hilum, to the second portion of the duodenum. Inferiorly, the right kidney is con- fined by the curvature of the right colon. Posteriorly, the relationships of both kidneys with the lumbar quadrate muscle and, more medially, the psoas muscles can be appreciated. b The anterior surface of the left kidney has a direct relationship with the tail of the pancreas, its superior pole with the spleen, and the hilum with the small bowel. Both the lateral profile and the inferior pole of the left kidney are related to the descending colon 172 S. Merola et al.

Left renal artery Right renal artery

Left renal vein Lumbar spine

Superior mesenteric artery

Right renal artery Left renal vein

Left renal artery

Aorta

Right renal artery Left renal artery

Segmental artery

Fig. 27.3 a Classically, each kidney is supplied by a single renal artery and a single renal vein, aris- ing from the abdominal aorta and inferior vena cava, respectively. These vessels typically originate off the aorta at the level of L2, below the takeoff of the superior mesenteric artery, with the vein anterior to the artery. b The right renal artery typically demonstrates a long downwards course to the relatively inferior right kidney, traversing behind the inferior vena cava. Conversely, the left renal artery, which arises below the right renal artery and has a more horizontal orientation, takes a rather direct upwards course to the more superiorly positioned left kidney. In addition, both renal arteries course in a slightly posterior direction because of the position of the kidneys. c The main renal artery divides into five segmental arteries near the renal hilum. The first division is typically the posterior branch. The main renal artery then continues before dividing into four anterior branch- es at the renal hilum: the apical, upper, middle, and lower anterior segmental arteries 27 Kidneys and Ureters 173

Liver Spleen

Renal hilum Renal cortex

Renal medulla

Psoas muscle

Diaphragm

Liver Pyramids

Renal medulla Renal sinus (pyramids)

Psoas muscle

Renal calyx Renal calyx Renal pelvis Renal pelvis

Lumbar vertebra Ureter

Fig. 27.4 a The corticomedullary phase is characterized by intense enhancement of the renal cortex and renal columns. b In the nephrographic phase, the attenuation of the renal medulla slowly in- creases until this portion of the kidney becomes isoattenuated or even hyperattenuated relative to the renal cortex. c The excretory phase shows opacification of the pyelocaliceal system 174 S. Merola et al.

Renal pelvis

Lumbar ureter

Sacrum Ureter

Urinary bladder

Inferior vena cava Renal pelvis

Calix

Lumbar vertebra

Inferior vena cava

Ureter Ureter

Psoas muscle

Fig. 27.5 a Volume rendering reconstruction shows the ureters as muscular tubes that propel urine from the kidneys to the urinary bladder. The ureters arise from the renal pelvis, on the medial as- pect of each kidney, before descending towards the bladder on the front of the psoas major muscle. They cross the pelvic brim near the bifurcation of the iliac arteries (which they traverse) to run posteroinferiorly on the lateral walls of the pelvis. They then curve anteromedially to enter the bladder through the back, at the vesicoureteric junction, running within the wall of the bladder for a few centimeters. b On axial scan, the ureters are situated at the pelviureteric junction. c The abdominal part of the ureter is located anteromedially, on the psoas muscle 27 Kidneys and Ureters 175

Right ureter Left ureter

Calyx Psoas muscle

Right ureter Left ureter

Internal External iliac iliac artery artery

Sacrum

Urinary bladder

Left ureter Right ureter

Fig. 27.6 a In this scan, the ureters are located anterior to the psoas muscle. The right ureter, in its downwards course, lies to the right of the inferior cava, while the left ureter is crossed by the left colic vessels. b The ureter crosses the pelvic brim at the level of the bifurcation of the common iliac artery. c The ureter descends along the retroperitoneal pelvic wall to the ureteral orifice located on the posterolateral wall of the bladder