<prompt> Poal vein is formed ?Behind the spleenBehind the tail of pancreasBehind the neck of pancreasBehind the second pa of duodenum  <response>: The poal vein is about 8 cm long.It is formed by union of superior mesenteric vein and splenic vein behind the neck of pancreas at the level of L2 veebrae in front of inferior vena cava IVC. 