Chap1N Anatomy of kidney

First and most constant branch is the posterior segmental branch, which separates from the renal artery before it enters the renal hilum.

Four anterior branches

• Posterior segmental branch passes posterior to the renal pelvis while the others pass anterior to the renal pelvis.
• 

UPJO  caused by a crossing vessel can occur when the posterior segmental branch passes anterior to the ureter causing occlusion.

Between these circulations is an avascular plane. This longitudinal plane lies just posterior to the lateral aspect of the kidney.

Unlike the arterial supply, the venous drainage communicates freely through venous collars around the infundibula, providing for extensive collateral circulation in the venous drainage of the kidney.

Surgically, this is important because unlike the arterial supply, occlusion of a segmental venous branch has little effect on venous outflow.

• Left adrenal vein superiorly
• Lumbar vein posteriorly
• Left gonadal vein inferiorly

Aberrant renal artery: supplying the superior and/or inferior pole of the kidney. 

Accessory renal artery: supplying the renal hilum.

Early branching (or prehilar branching): occurs within 1.5-2.0 cm of origin in the left renal artery or in the retrocaval segment of the right renal artery

Left - Left lateral para-aortic lymph nodes 

Right - right interaortocaval and right paracaval lymph nodes

• Upper ureter - from the renal pelvis to the upper border of the sacrum.
• Middle ureter - from the upper to the lower border of the sacrum.
• Lower (distal or pelvic) ureter - from the lower border of the sacrum to the bladder

• Abdominal ureter - from a medial direction
• Pelvic ureter - from a lateral direction

After reaching the ureter, the arterial vessels course longitudinally within the periureteral adventitia in an extensive anastomosing plexus. It is this longitudinal vascularity that allows the ureter to be safely mobilized from the surrounding retroperitoneal tissues without compromising the vascular supply, provided that the periureteral adventitia is not stripped.

The exact role of the  ureteral autonomic input is unclear. Normal ureteral peristalsis does not require outside autonomic input but, rather, originates and is  propagated from intrinsic smooth muscle pacemaker sites located in the minor calyces of the renal collecting system.