The sphincter of Oddi is a smooth muscle valve that regulates the flow of bile and pancreas into the duodenum, first described by the Italian anatomist, Ruggero Oddi, in 1887. Sphincter of Oddi dysfunction (sphincter of Oddi D) is a broad term used to describe many disorders of the biliary, pancreatic, and hepatic systems that result from inappropriate contraction, tightening, and relaxation of this valve.