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The first division of the small intestine, about 25 cm or 12 fingerbreadths (hence the name) in length, extending from the pylorus to the junction with the jejunum at the level of the first or second lumbar vertebra on the left side. It is divided into the superior part, the first part of which is the duodenal cap, the descending part, into which the bile and pancreatic ducts open, the horizontal (inferior) part and the ascending part, terminating at the duodenojejunal junction. [Mediev. L. fr. L. duodeni, twelve]
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du·o·de·num .d(y)ü-ə-'dē-nəm, d(y)u̇-'äd-ən-əm n, pl -de·na -'dē-nə, -ən-ə or -de·nums the first, shortest, and widest part of the small intestine that in humans is about 10 inches (25 centimeters) long and that extends from the pylorus to the undersurface of the liver where it descends for a variable distance and receives the bile and pancreatic ducts and then bends to the left and finally upward to join the jejunum near the second lumbar vertebra
du·o·de·nal -'dēn-əl, -ən-əl adj
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n.
the first of the three parts of the small intestine. It extends from the pylorus of the stomach to the jejunum. The duodenum receives bile from the gall bladder (via the common bile duct) and pancreatic juice from the pancreas. Its wall contains various glands (including Brunner's glands) that secrete an alkaline juice, rich in mucus, that protects the duodenum from the effects of the acidic chyme passing from the stomach.
• duodenal adj.
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du·o·de·num (doo″o-deґnəm) (doo-odґə-nəm) [L. duodeni twelve at a time] [TA] the first or proximal portion of the small intestine, much shorter than the following portions, extending from the pylorus to the jejunum; so called because its length is about 12 finger breadths. duodenal adjMedical dictionary. 2011.