GI Tract
54 Anatomy, Histology, and Cell Biology
Peritoneal (supported by mesentery) Abdominal esophagus, stomach, superior
duodenum, liver, pancreatic tail, jejunum,
ileum, a variable portion of the cecum,
appendix, transverse colon, and sigmoid colon
Secondarily retroperitoneal (adherent) Descending and inferior duodenum, pancreatic
head and body, ascending colon, and
descending colon. These may be surgically
mobilized with an intact blood supply
Extra/retroperitoneal Thoracic esophagus, rectum, kidneys, ureters,
and adrenal glandsCHARACTERIZATION OF ABDOMINAL STRUCTURES
BY LOCATION AND SUPPORT
Characterization Organ- Peptic ulcerationof the lower esophagus, stomach, or superior duode-
num is referred along the greater splanchnic nerve to the fifth and sixth
dermatomes, which include the epigastric region. - The hepatic triangle,bounded by the cystic duct, gallbladder, and com-
mon hepatic duct, contains the cystic arteries and right hepatic artery
with potential for extensive variation. - The duodenal papillausually contains the hepatopancreatic ampulla,
formed by the joining of the common bile duct and the pancreatic duct.
If blocked by a stone, pancreatitis may develop. - The tail of the pancreascontains most of the pancreatic islets (of
Langerhans), a consideration in pancreatic resection. - Ileal (Meckel’s) diverticulumis found in about 2% of the population,
located within 2 ft of the ileocecal junction (on the anti-mesenteric side
of the ileum), and usually about 2 in. long. Often contain two types of
ectopic tissue (cardiac and pancreatic). Peptic ulceration of adjacent ileal
mucosa and volvulus are complications. - The hepatic portal veindirects venous return from the gastrointestinal
tract to the liver. - Because the hepatic portal system has no valves,blood need not flow
toward the liver. Liver disease (such as cirrhosis) or compression of a
vein (as in pregnancy or constipation) results in blood shunting through
the anastomotic connections to the systemic venous system.