Accessory renal aery:-
High-Yield Explanation
The accessory renal aery is the precocious origin of a segmental aery which sometimes arises from the aoa and supplies upper or lower pole of the kidney. The accessory renal aery is the remnant of the degenerated mesonephric aery. The aery for the lower pole usually passes behind the pelvis of ureter and may cause obstruction to urine flow producing hydronephrosis.