<prompt> A 49 year old man suffering from carcinoma of prostate was x -rayed. He showed areas of sclerosis and collapse of T 10 and T11 veebrae in x-ray. The spread of this cancer to the above veebrae was through -Sacral canalLymphatic vesselsInternal veebral plexus of veinsSuperior rectal vein  <response>: Ans is c i.e. Internal veebral plexus of veins Prostatic cancer spreads to the bones through blood vessels; first into Batsons periprostatic venous plexus and then into the internal veebral plexus of veins. This metastatis is possible because of valveless communication between the periprostatic and veebral plexus of veins. 