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Foregut, Midgut, & Hindgut

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wiheramu's version from 2016-05-22 11:12

foregut

development & spaces of foregut
Question Answer
foregut is supplied by what artery?celiac artery
what organs are derived from the foregut?- stomach - liver - gallbladder - pancreas - duodenum (1&2)
the greater curvature is the embryonic (D/V) side of the stomachdorsal
how are greater/lesser curvatures madedorsal stomach grows more than ventral
how does greater curvature find its way from dorsal --> ______left, by rotating 90 degrees clockwise
rotation of stomach (& consequent pouching of mesentery) formslesser sac (R of dorsal mesentery)
lesser sac is also calledomental bursa
omental bursa is also calledlesser sac
what do we call dorsal/ventral mesoderm near stomach?dorsal/ventral mesogastrium
space behind the stomach is calledlesser sac
what's behind the lesser sac?pancreas
what & where is the entrance to the lesser sac?foramen of Winslow
- behind pyloris (to R of stomach)
greater omentum is formed fromovergrowth of mesogastrium (rotation of stomach)
the greater omentum hangs frominferior surface of stomach
greater omentum overliestransverse colon
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organs of foregut
Question Answer
what is the entrance to the stomach called?cardiac orifice (gastroesophageal jxn)
top apex of stomachfundus
middle long part of stomachgastric canal
narrowing of stomachpyloric antrum --> pyloric canal
where is the cardia of the stomach?near the entrance of the esophagus
first part of duodenum is also calledsuperior (it's horizontal)
2nd part of duodenum is also calleddescending
where is the boundary of fore-midgut?at 2-3 duodenum
what parts of duodenum are intraperitoneal?1 & 4
3rd part of duodenum is also calledhorizontal
4th part of duodenum is also calledascending
1st part of the duodenum is (intra/retro)peritonealintraperitoneal
2nd part of the duodenum is (intra/retro)peritonealsecondarily retroperitoneal
3rd part of the duodenum is (intra/retro)peritonealsecondarily retroperitoneal
4th part of the duodenum is (intra/retro)peritonealintraperitoneal
where does the spleen develop?in dorsal mesogastrium
fxn of adult spleenstores & recycles blood
most vascular organ of bodyspleen (350 L passes / day)
most commonly injured organ when thoracoabdominal trauma occursspleen (25% blunt injuries to abdominal viscera)
pancreas develops fromventral & dorsal pancreas (come together when gut rotates)
why is the fusion of dorsal & ventral pancreatic ducts significant clinically?- failure to fuse
- annular pancreas
- can constrict gut tube
superior mesenteric a & v are wrapped by what organ?pancreas (between primordial ventral & dorsal pancreas)
"nutcracker effect"left renal vein between the abdominal aorta (AA) and superior mesenteric artery (
pancreas is intra/retro)peritonealsecondarily retroperitoneal
duodenum wraps aroundhead of pancreas
what wraps head of pancreas?duodenum
fxn of hepatic arterysupplies liver with blood
fxn of portal veinblood from small intestines -> liver
fxn of bile ductenzymes from gallbladder -> small intestine
portal triad consists of- hepatic artery
- portal ven
- bile duct
porta hepatis"door to liver"
- where substances enter/leave liver (portal triad)
where do substances enter & leave the liver?porta hepatis
how many functionally independent segments does the liver have?8!
what makes up a surgical lobe of the liver?- branch of hepatic artery
- branch of protal vein
- hepatic duct
the surgical lobes of the liver do/not correspond to anatomical lobesdo NOT
what structure of the liver is intersegmentalhepatic veins
anterior contacts of liver2 remnants of ventral mesentery
- falciform ligament
- lesser omentum
what does falciform mean?sickle-shaped
what is the lesser omentum?anterior wall of lesser sac
2 parts of lesser omentum- hepatogastric ligament
- hepatoduodenal ligament
lesser omentum is part of (D/V) mesenteryventral
the portal triad travels withhepatoduodenal ligament
what is the Pringle maneuver?surgical technique
- clamp hepatoduodenal ligament to stop bloodflow to liver
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neurovasculature of foregut
Question Answer
3 branches of celiac artery- L gastric
- splenic
- common hepatic
parasympathetic innervation to foregut is viavagus (CN X)
parasympathetic motor innervation to foregut action- varies by organ
- increases motility of gut
- aids in digestion
parasympathetic sensory innervation to foregut carries what information?afferent reflexes (controls digestion)
which organ of foregut has little to no parasympathetic innervationspleen (not even really foregut)
sympathetic innervation to foregut is viasplanchnic branches of sympathetic chains
sympathetic innervation of esophagus is viaT5-6 sympathetic chain
sympathetic innervation of stomach is viaT6-10 sympathetic chain
sympathetic innervation of spleen is viaT6-10 sympathetic chain
sympathetic innervation of pancreas is viaT6-10 sympathetic chain
sympathetic innervation of liver is viaT7-9 sympathetic chain
sympathetic innervation of gallbladder is viaT7-9 sympathetic chain
sympathetic motor innervation to foregut action- varies by organ
- decreases motility of gut
- inhibits digestion
sympathetic sensory innervation to foregut carries what information?pain -> TL spinal cord
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midgut & hindgut

Question Answer
midgut is supplied by what artery?superior mesenteric a.
what organs are derived from the midgut?- duodenum (3&4) - jejunum - ileum - cecum - appendix - ascending colon - transverse colon (1st half)
hindgut is supplied by what artery?inferior mesenteric a.
what organs are derived from hindgut?- transverse colon (2nd half)  -descending colon - sigmoid colon - rectum
where is transition from mid-> hindgut?2/3 way through transverse colon
how do vessels of colon communicate with each other?marginal artery (of Drummond)
fxn of marginal artery (of Drummond)communication between vessels of colon
why is stenosis of IMA not a huge issuemarginal artery of Drummond maintains allows SMA to supply gut tube
flexures of colonR colic flexure (hepatic) & L colic flexure (splenic)
R colic flexure is also calledheaptic flexure
L colic flexure is also calledsplenic flexure
3 parts of small intestineduodenum, jejunum, ileum
branches connecting main branches --> small intestinesvasa recta (straight vessels)
(jejunum/ileum) is longerileum
(jejunum/ileum) has longer vasa rectajejunum
(jejunum/ileum) has few arcades of arteriesjejunum
(jejunum/ileum) has shorter vasa rectaileum
(jejunum/ileum) has more arcades of arteriesileum
(jejunum/ileum) has thicker wallsjejunum
(jejunum/ileum) has thinner wallsileum
(jejunum/ileum) has less fat in mesenteryjejunum
(jejunum/ileum) has more fat in mesenteryileum
(jejunum/ileum) has large, closely packed circular foldsjejunum
(jejunum/ileum) has more sparse circular foldsileum
circular folds are also calledplicae circularis
where does the small intestine terminate?ileocecal jxn
what is the cecum?blind pouch at start of large intestine
where is the appendix?off the cecum
appendix is also calledvermiform or cecal appendix
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midgut development
Question Answer
where is the midgut before body folding has completed?outside the body (herniates into umbilical cord)
what occurs DURING herniation- first 90 degrees of rotation
- coiling of SI loops
- formation of cecum
total rotation of the midgut during development270 degrees CCW
when does rotation 0-90 occur?during herniation
when does rotation 90-180 occur?after herniation
when does rotation 180-270 occur?after herniation
what direction does the midgut rotate?counter clockwise
the cecum descends from liver before/after/during herniationafter
ascending & descending colon are (intra/retro)peritonealsecondarily retroperitoneal
when is the location of ascending & descending colon fixed?as herniated gut comes back into abdomen
most common congenital anomaly of intestinenonrotation
what is a nonrotation congenital anomaly of intestinefailure of normal CCW rotation around the SMA
in the case of congenital nonrotation, where is the small intestine relative to the SMA?to the right of the artery
in the case of congenital nonrotation, where is the cecum?near midline
in the case of congenital nonrotation, where is the colon?L abdomen
in the case of congenital nonrotation, where is the small intestine?R abdomen
incomplete rotation usually stops at about what degree?180
in the case of congenital incomplete rotation, where is the cecum?upper abdomen
in the case of congenital incomplete rotation, where is the DJ jxn?just short of its L abdomen destination
people with ________ are susceptible to volvuluscongenital incomplete rotation
what is volvulusrotation of loop of bowel on its mesentery
volvulus can causeacute bowel obstruction / ischemia
fixation of ascending & descending colon to wall of intestine helps preventvolvulus
what pulls the intestine out --> herniationyolk stalk
what is Meckel's diverticulum?persistent vitelline (yolk) duct
how common is Meckel's diverticulum2-4% of population (often asymptomatic)
how does Meckel's diverticulum present?- blind pouch (from yolk stalk) on antimesentery border (opp side as mesentery) of ileum

- occasionally ligament connecting ileum--> umbilicus 
how can Meckel's diverticulum become problematic?inflammation
ulcer
volvulus (if ligament)

- fistula (rare)
define fistulaabnormal passageway
if hernia doesn't completely retract...omphalocele
what is an omphalocele?persistence of herniation of ab contents --> umbilical cord
- failure to retract
- organs covered by peritoneum
in (omphalocele/ gastroschisis), organs are covered by peritoneumomphalocele
in (omphalocele/ gastroschisis), organs are NOT covered by peritoneumgastroschisis
(omphalocele/ gastroschisis) is caused by failure of body wall to fusegastroschisis
(omphalocele/ gastroschisis) is caused by persistence of herniation of abdominal contentsomphalocele
in (omphalocele/ gastroschisis), umbilicus is involvedomphalocele
if body wall fails to fuse...gastroschisis
what is gastroschisis?failure of body wall to fuse
or inadequate enlargement of peritoneal cavity
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hindgut development
Question Answer
cloaca meanssewer
the common cloaca (early in development) includesdistal end of gut tube
& distal end of urogenital pathway are connected
what divides the common cloaca?urorectal septum
what divides the uro-genital outflow?perineum
cloacal membrane becomesurogenital & anal membranes
what is persistent anal membraneanal membrane never opens, rectum has no exit
what is anoperineal fistulaanus is farther anterior than normal
what is rectovaginal fistularectum connected to vaginal opening
what is rectourethral fistularectum connected to urethra
what is rectovesical fistularectum connected to bladder
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innervation of midgut
Question Answer
parasympathetic innervation to midgut is viavagus (CN X)
parasympathetic motor innervation to midgut action- varies by organ
- increases motility of gut
- aids in digestion
parasympathetic sensory innervation to midgut carries what information?afferent reflexes (controls digestion)
sympathetic innervation to midgut is viasplanchnic branches of sympathetic chains
- lesser splanchnic
- least splanchnic
- lumbar splanchnic 
sympathetic motor innervation to midgut action- varies by organ
- decreases motility of gut
- inhibits digestion
sympathetic sensory innervation to midgut carries what information?pain -> TL spinal cord
sympathetic innervation of small intestine is viaT9-10 sympathetic chain
sympathetic innervation of appendix is viaT10 sympathetic chain
sympathetic innervation of cecum -> L colic flexure is viaT11 -L1 sympathetic chain
important landmark of innervation to midgutappendix @ T10
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Question Answer
parasympathetic innervation to hindgut is viapelvis splanchnic nerves
parasympathetic motor innervation to hindgut action- varies by organ
- increases motility of gut
- aids in digestion
parasympathetic sensory innervation to hindgut carries what information?afferent reflexes (controls digestion)
sympathetic innervation to hindgut is viasplanchnic branches of sympathetic chains
- lumbar splanchnic
-sacral splanchnic 
sympathetic innervation of L colic flexure -> rectum is viaL1-2 sympathetic chain
sympathetic motor innervation to hindgut action- varies by organ
- decreases motility of gut
- inhibits digestion
sympathetic sensory innervation to hindgut carries what information?pain -> TL spinal cord
what are pelvic splanchnics?parasympathetic nerves from SACRAL (not cranial like vagus) spinal cord
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