Duodenum shine kashi na farko kuma mafi guntu na ƙananan hanji. Bututu ne mai siffar C wanda ke haɗa ciki zuwa jejunum, sashi na biyu na ƙananan hanji. Sunan "duodenum" ya fito ne daga kalmar Latin "duodenum digitorum," wanda ke nufin "yatsu goma sha biyu," saboda tsayin duodenum yana daidai da faɗin yatsu goma sha biyu.
