All of the following form posterior relations of head of pancreas, except
First pa of duodenum forms the anterior relation of head of pancreas while all others form the posterior relations. Anterior relations of head of pancreas include first pa of duodenum, transverse colon, jejunum . Posterior relations include inferior vena cava, terminal pas of renal veins, right crus of diaphragm and bile duct. ref - BDC 6e vol2 pg300
Common Bile Duct
First pa of duodenum
Aoa
Inferior Vena cava
Abdomen and pelvis