Lower GI Tract Flashcards
which part of the duodenum has a mesentary?
only the first segment
is the duodenum intraperitoneal or retroperitoneal?
the first segment is intraperitoneal. the last 3 are retroperitoneal
which part of the duodenum does the common bile duct and pancreatic duct drain into?
second
what marks the caudal limit of the ventral mesentary?
the bile duct
what two organs run posterior to the superior mesenteric artery and anterior to the aorta?
the left renal vein and the third portion duodenum
what ligament suspends the dudenojejunal junction?
the ligament of Treitz
is the duodenum foregut, midgut, or hindgut?
the first portion is foregut, the last 3 segments are midgut
what vessels supply the duodenum
the superior pancreaticoduodenal artery supplies the first segment of the duodenum. the superior mesenteric artery supplies the distal 3 segments
what structure separates the secum from the ileum
the ileocecal valve
what marks the junction between the jejunum and ileum
there is no clear demarcation
are the jejunum and ileum intraperitoneal or retroperitoneal?
intraperitoneal. they are suspended by a mesentary which runs from the duodenojejunal junction to the ileocecal valve.
describe the differences in the vasculature in the mesentaries of the jejunum and ileum?
jejunum has fewer vascular arcades and longer vasa recta. ileum has more arcades and shorter vasa recta.
describe the peritoneal gutters
there are “gutters” on either side of the ascending and descending colon. the medial ascending gutter cannot drain into the pelvic cavity because it is occluded by the small bowel
what is the structure called where the bile and pancreatic ducts enter the duodenum
major papilla. ampulla of vater.
what are the folds of the small bowels? how do they change as the small bowel continues?
plicae circulares. they increase surface area for absorption. they increase in size and frequency in the ileum
plicae semilunares
these are folds which do not form complete circles around the bowel and are found in the large intestine
describe sympathetic innervation to the small bowel
splanchnic nerves to the preaortic ganglia (at the celiac trunk)
describe parasympathetic innervation to the small bowel
vagus nerve
what are the 3 longitudinal muscles along the large intestine?
taeniae coli
what are the large outpouchings of the large intestine?
haustra
what are the small collections of fatty tissue on the large intestine surface?
epiploicae appendices
is the cecum retro or intraperitoneal?
intraperitoneal but it does not have a mesentary
where is the transition from the mid to hindgut?
along the transverse colon distal to the splenic flexure
what blood vessels supply the hindgut?
the inferior mesenteric arteries
where does the parasympathetic innervation of the hindgut come from?
pelvic splanchnic with postganglionic nuclei in the inferior mesenteric ganglia
what arteries supply the ascending colon? the descending colon?
ascending- ilecolic, right colic, and middle colic. all originate from the SMA.
descending- left colic and sigmoid arteries. originate from the IMA.
how is the appendix created?
its found on the cecum where the 3 taeniae coli converge
SMA syndrome
in very thin females, the angle between the SMA and aorta becomes so narrow that it obstructs the duodenum
where does the IMV drain?
splenic vein
where do pelvic splanchnic nerves arise?
s2-4
where do the lymphatics ultimately drain in the bowels?
the drain into the superior and inferior mesenteric nodes at the aorta, which drain into the cisterna chyli, which begins the thoracic duct
