Foregut, Midgut, & Hindgut

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 stomach	dorsal
how are greater/lesser curvatures made	dorsal 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) forms	lesser sac (R of dorsal mesentery)
lesser sac is also called	omental bursa
omental bursa is also called	lesser sac
what do we call dorsal/ventral mesoderm near stomach?	dorsal/ventral mesogastrium
space behind the stomach is called	lesser 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 from	overgrowth of mesogastrium (rotation of stomach)
the greater omentum hangs from	inferior surface of stomach
greater omentum overlies	transverse colon
	memorize

 

organs of foregut

Question	Answer
what is the entrance to the stomach called?	cardiac orifice (gastroesophageal jxn)
top apex of stomach	fundus
middle long part of stomach	gastric canal
narrowing of stomach	pyloric antrum --> pyloric canal
where is the cardia of the stomach?	near the entrance of the esophagus
first part of duodenum is also called	superior (it's horizontal)
2nd part of duodenum is also called	descending
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 called	horizontal
4th part of duodenum is also called	ascending
1st part of the duodenum is (intra/retro)peritoneal	intraperitoneal
2nd part of the duodenum is (intra/retro)peritoneal	secondarily retroperitoneal
3rd part of the duodenum is (intra/retro)peritoneal	secondarily retroperitoneal
4th part of the duodenum is (intra/retro)peritoneal	intraperitoneal
where does the spleen develop?	in dorsal mesogastrium
fxn of adult spleen	stores & recycles blood
most vascular organ of body	spleen (350 L passes / day)
most commonly injured organ when thoracoabdominal trauma occurs	spleen (25% blunt injuries to abdominal viscera)
pancreas develops from	ventral & 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)peritoneal	secondarily retroperitoneal
duodenum wraps around	head of pancreas
what wraps head of pancreas?	duodenum
fxn of hepatic artery	supplies liver with blood
fxn of portal vein	blood from small intestines -> liver
fxn of bile duct	enzymes 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 lobes	do NOT
what structure of the liver is intersegmental	hepatic veins
anterior contacts of liver	2 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) mesentery	ventral
the portal triad travels with	hepatoduodenal ligament
what is the Pringle maneuver?	surgical technique - clamp hepatoduodenal ligament to stop bloodflow to liver
	memorize

 

neurovasculature of foregut

Question	Answer
3 branches of celiac artery	- L gastric - splenic - common hepatic
parasympathetic innervation to foregut is via	vagus (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 innervation	spleen (not even really foregut)
sympathetic innervation to foregut is via	splanchnic branches of sympathetic chains
sympathetic innervation of esophagus is via	T5-6 sympathetic chain
sympathetic innervation of stomach is via	T6-10 sympathetic chain
sympathetic innervation of spleen is via	T6-10 sympathetic chain
sympathetic innervation of pancreas is via	T6-10 sympathetic chain
sympathetic innervation of liver is via	T7-9 sympathetic chain
sympathetic innervation of gallbladder is via	T7-9 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
	memorize

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 issue	marginal artery of Drummond maintains allows SMA to supply gut tube
flexures of colon	R colic flexure (hepatic) & L colic flexure (splenic)
R colic flexure is also called	heaptic flexure
L colic flexure is also called	splenic flexure
3 parts of small intestine	duodenum, jejunum, ileum
branches connecting main branches --> small intestines	vasa recta (straight vessels)
(jejunum/ileum) is longer	ileum
(jejunum/ileum) has longer vasa recta	jejunum
(jejunum/ileum) has few arcades of arteries	jejunum
(jejunum/ileum) has shorter vasa recta	ileum
(jejunum/ileum) has more arcades of arteries	ileum
(jejunum/ileum) has thicker walls	jejunum
(jejunum/ileum) has thinner walls	ileum
(jejunum/ileum) has less fat in mesentery	jejunum
(jejunum/ileum) has more fat in mesentery	ileum
(jejunum/ileum) has large, closely packed circular folds	jejunum
(jejunum/ileum) has more sparse circular folds	ileum
circular folds are also called	plicae 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 called	vermiform or cecal appendix
	memorize

 

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 development	270 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 herniation	after
ascending & descending colon are (intra/retro)peritoneal	secondarily retroperitoneal
when is the location of ascending & descending colon fixed?	as herniated gut comes back into abdomen
most common congenital anomaly of intestine	nonrotation
what is a nonrotation congenital anomaly of intestine	failure 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 volvulus	congenital incomplete rotation
what is volvulus	rotation of loop of bowel on its mesentery
volvulus can cause	acute bowel obstruction / ischemia
fixation of ascending & descending colon to wall of intestine helps prevent	volvulus
what pulls the intestine out --> herniation	yolk stalk
what is Meckel's diverticulum?	persistent vitelline (yolk) duct
how common is Meckel's diverticulum	2-4% 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 fistula	abnormal 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 peritoneum	omphalocele
in (omphalocele/ gastroschisis), organs are NOT covered by peritoneum	gastroschisis
(omphalocele/ gastroschisis) is caused by failure of body wall to fuse	gastroschisis
(omphalocele/ gastroschisis) is caused by persistence of herniation of abdominal contents	omphalocele
in (omphalocele/ gastroschisis), umbilicus is involved	omphalocele
if body wall fails to fuse...	gastroschisis
what is gastroschisis?	failure of body wall to fuse or inadequate enlargement of peritoneal cavity
	memorize

 

hindgut development

Question	Answer
cloaca means	sewer
the common cloaca (early in development) includes	distal 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 becomes	urogenital & anal membranes
what is persistent anal membrane	anal membrane never opens, rectum has no exit
what is anoperineal fistula	anus is farther anterior than normal
what is rectovaginal fistula	rectum connected to vaginal opening
what is rectourethral fistula	rectum connected to urethra
what is rectovesical fistula	rectum connected to bladder
	memorize

 

innervation of midgut

Question	Answer
parasympathetic innervation to midgut is via	vagus (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 via	splanchnic 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 via	T9-10 sympathetic chain
sympathetic innervation of appendix is via	T10 sympathetic chain
sympathetic innervation of cecum -> L colic flexure is via	T11 -L1 sympathetic chain
important landmark of innervation to midgut	appendix @ T10
	memorize

 

Question	Answer
parasympathetic innervation to hindgut is via	pelvis 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 via	splanchnic branches of sympathetic chains - lumbar splanchnic -sacral splanchnic
sympathetic innervation of L colic flexure -> rectum is via	L1-2 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
	memorize