Small Intestine

The small intestine is a coiled tube about 20 feet in length and is located in the center of the lower abdomen. The small intestine is divided into three arbitrary sections: the duodenum, the jejunum and the ileum, note however that these three sections are indistinct as the intestines are continuous. The duodenum begins at the pyloric opening with the stomach. It is C shaped and bound to the abdomen by the peritoneum (the lining of the abdomen). The duodenum is in close contact with several other abdominal organs including the liver, pancreas, gallbladder and left kidney. At about the level of the 2nd lumbar vertebra it becomes the jejunum. The jejunum segment is about nine feet long and is similar in appearance to the duodenum. The ileum is the last segment of the small intestine beginning at the jejunum and ending at the junction with the large intestine. It is smaller in diameter than the jejunum but longer and its walls are thinner and are less vascularized. Both the jejunum and ileum are completely covered by the peritoneum