<prompt> Portal vein is formed -Behind the spleenBehind the tail of pancreasBehind the neck of pancreasBehind the second part of duodenum  <response>: Ans. is c i.e.. Behind the neck of the pancreas o The portal vein is about 8 cm long.o It is formed by union of superior mesenteric vein and splenic vein behind the neck of pancreas at the level of L2 vertebrae in front of inferior vena cava LVC. 