Small Intestine, Anatomy and Histology
The small intestine is a specialized tubular structure within the abdominal cavity in continuity with the stomach proximally and the colon distally. The small bowel is about 6 m in the adult. Three subdivisions; “the duodenum, jejunum, and ileum”are defined and characterized by various anatomic relationships. The first 25 cm of small intestine, the duodenum; excluding the most proximal several centimeters, is a fixed, retroperitoneal structure that forms a C- or U-shape around the head of the pancreas. Four subdivisions of the duodenum have been described: (a) the first portion, the duodenal bulb, is the most proximal and superior segment; (b) the descending or second portion, which the common bile duct and major and minor pancreatic ducts empty into the papillae; (c) the horizontal or third portion; and (d) the ascending or fourth portion. Duodenum ends at the ligament of Treitz, where it turns to the peritoneal cavity. The remainder of the...
References and Further Reading
- Adler, D. G., Crawford, J. M., & Farraye, F. A. (2015). GI tract endoscopic and tissue processing techniques and normal histology. In R. D. Odze & J. R. Goldblum (Eds.), Surgical pathology of the GI tract, liver, biliary tract and pancreas (pp. 4–33). Philadelphia: Elsevier.Google Scholar
- Bass, L. M., & Wershil, B. K. (2016). Small and large intestine. In M. Feldman, L. S. Friedman, & L. J. Brandt (Eds.), Sleisenger & Fordtran’s gastrointestinal and liver disease (pp. 1649–1678). Philadelphia: Elsevier.Google Scholar
- Katzin, W. E., & Petras, R. E. (2012). Small intestine. In S. E. Millis (Ed.), Histology for pathologists (pp. 647–672). Philadelphia: Lippincott.Google Scholar