Foregut, Midgut, & Hindgut


foregut
development & spaces of foregutQuestion | 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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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