Esophagogastrointestinal Tract

Abstract

In the earliest days of its development, the gastrointestinal tract is represented as a straight tube of uniform caliber which is suspended in the midline of the abdominal cavity by a ventral and a dorsal mesentery (Fig. 338). The dorsal mesentery extends along the entire length of this tube; it may be subdivided into mesogastrium, mesoduodenum, mesojejunum, mesoileum and the various mesocola. However, the ventral mesentery extends only as far as the first inch of the duodenum or, in other words, as far as the umbilicus; it is referred to as the ventral mesogastrium. The straight gastrointestinal tube lies between 2 layers of mesentery and therefore has right and left surfaces. The aorta supplies the entire tube by means of 3 branches: the celiac axis and the superior and the inferior mesenteric arteries. The celiac axis supplies the foregut (stomach and duodenum as far as the entrance of the bile duct). The superior mesenteric artery supplies the midgut (from the entrance of the bile duct to the junction of the middle and the left thirds of the transverse colon). The inferior mesenteric artery supplies the hindgut (from the left third of the transverse colon to the rectum).