renal sinus renal sinus the renal sinus is a cavity within the kidney which is occupied by the renal pelvis, renal calyces, blood vessels, nerves and fat. the renal hilum extends into a large cavity within the kidney occupied by the renal vessels, minor renal calyces, major renal calyces, renal pelvis and some adipose tissue. renal sinusdetailssystemurinary systemidentifierslatinsinus renalista98a08.1.01.005ta23362fma15611anatomical terminology additional images renal sinus renal sinus