Development of the Abdomen Flashcards
during third week of development what does the embryo become and what are the layers called
trilaminar disc three layers of disc (germ layers) ectoderm (continuous with amnion) mesoderm (single horseshoe shaped canal- intraembryonic coelom) endoderm (continuous with yolk sac)
what directions does the embryo fold and what does this do
craniocaudally
laterally
canals and part of yolk sac are incorporated into embryo
what is the result of embryonic folding
gut tube (endoderm surrounded by support mesoderm) suspended inside cavity b/w a dorsal and a ventral connection to the body wall
by the 5th week of development there is a single gut tube suspended by what?
THE dorsal mesentery
Major developmental events of the gastrointestinal system occur when in embryonic life (and what marks the beginning and the end
between
4th week- initial dilation of stomach
and 10th week- return of herniated loops of intestine
foregut derivatives are suppled by what artery
celiac artery
foregut derivaties are (name the organs)
esophagus stomach (gaster) proximal half of duodenum liver (hepar) gall pladder pancrease
the respiratory diverticulum is an outgrowth of what section of the gut and forms what?
foregut outgrowth
forms: larynx, trachea, and lungs
the foregut includes what (name of the gut and its extension from where to where)?
pharyngeal gut from buccopharyngeal membrane to respiratory diverticulum
the foregut forms part of what cavity and what other structures (not abdominal organs)
oral cavity
pharynx
directs of the pharyngeal arches
midgut derivatives are supplied by what artery
Superior Mesenteric Artery
midgut derivaties (name the organs)
distal half of duodenum jejunum and ileum cecum and vermiform appendix ascending colon proximal 2/3 of transverse colon
hindgut derivatives are supplied by what artery
inferior mesenteric artery
hindgut derivaties (name the organs)
distal 1/3 of transverse colon
descending and sigmoid coon
superior 1/2 of rectum
the esophagus is formed by what?
a partition that develops in the foregut tube called the tracheoesophageal septum
formation of esophagus begins as what?
respiratory diverticulum (lung buds) that expand caudally forming the esophagotracheal ridge- this later forms the septum that separates pharynx into esophagus and trachea
the stomach starts as?
dilation (swelling) in tube (foregut)
what surface of the stomach grows faster?
dorsal surface grows faster than ventral surface
what surface becomes the greater curvature and why
dorsal surface
because it grows faster than the ventral surface
rotation of stomach during development does what?
causes the original ventral surface to move to the right and the original dorsal surface to move to the left
this makes the greater curvature end up on the left side in adults
rotation of stomach during development results in what structure?
lesser sac (omental bursa)
the composition of vagal trunks (left being anterior and right being posterior) can be explained by?
90 degree rotation of stomach on its longitudinal axis
the liver develops as what?
a bud (hepatic diverticulum) off the foregut
the liver grows in what direction pushing through what?
grows out ventrally
pushes through the inferior part of the septum transversum (later becomes ventral mesentery)
as the liver grows it does what (in relation to abdominal cavity) and this causes what
bulges into abdominal cavity
pulls the septum transversum with it
causes liver to be suspended b/w foregut and anterior abdominal wall by ventral mesentery (septum transversum)
the septum transversum (other than ventral mesentery) is a main component of what and is formed from what germ layer?
diaphragm
mesoderms
the falciform ligament (derived from what, connects what, carries what)
derived from ventral mesentery
liver to anterior abdominal wall
free margin carries umbilical vein (ligamentum teres)
lesser omentum (derived from what, what does it connect)
derived from ventral mesentery
connects liver to foregut
lesser omentum (named parts and what they connect)
hepatogastric ligament- liver to stomach
hepatoduodenal ligament- liver to duodenum (carries portal triad)
the septum transversum ultimately becomes what (in relation to liver and diaphragm)?
visceral peritoneum of liver
central tendon of diaphragm
the liver is enclosed in what?
visceral peritoneum of ventral mesentery
the part of the liver not covered by visceral peritoneum is called what
bare area
the gallbladder and ventral pancreatic bud arise from what?
hepatic diverticulum
dorsal pancreas develops as a bud off of what?
dorsal surface of developing duodenum
the common stay of the liver and gall bladder becomes what?
common bile duct
as the foregut rotates to the right what happens to duodenum
duodenum becomes C-shaped and ends up to the right of midline
as the foregut rotates to the right what happens to pancreas and bile duct and why
the pancreas and bile duct migrate dorsally
due to duodenum growing more quickly on the dorsal wall coupled with rotation
during what week do the two pancreatic buds fuse
6th week
the ventral pancreatic bud becomes what?
head and uncinate process
the dorsal pancreatic bud becomes what.
body and tail of pancreas
when the pancreatic buds fuse the ducts anastomose; what does each duct from each bud become (respectfully)
ventral bud- main pancreatic duct
dorsal bud- accessory pancreatic duct
Annular pancreas (what is it, what causes it, why is it significant)
rare congenital abnormality characterized by a ring of pancreatic tissue that encircles the descending portion of the duodenum
thought to originate from incomplete rotation of the pancreatic ventral bud
pancreatic tissue can constrict the duodenum and obstruct the intestine
Spleen (formation)
as an independent condensation of mesoderm between layers of the dorsal mesentery of the stomach
what abdominal organ is not an outgrowth of the gut
spleen
the part of the dorsal mesentery that extends posterior to the spleen does what
fuses to the posterior abdominal wall
the part of the dorsal mesentery between the spleen and the stomach becomes what?
gastrosplenic ligament
the confused part of the dorsal mesentery that extends posterior to the spleen becomes what?
splenorenal ligament
physiological umbilical herniation
normal
as the midgut elongates the intestinal loops project into the umbilical cord
Gastroschisis
ventral body wall defect that results in herniation of intestinal loops into the amniotic cavity
due to failure of the body wall to close
Omphalocele
ventral wall defect
caused when parts of the guy tube that normally hornet into the umbilical cord fail to return to the abdominal cavity
when the intestines project into the umbilical cord what happens to the midgut?
rotates 90 degrees counter clockwise
what type of rotation does the midgut undergo (and around what)
90 degree counter clockwise rotation along the axis of the superior mesenteric artery and vitelline duct
the cecum forms as what?
a swelling on the distal (caudal) loop
as the intestines return to the abdomen during the 10th week what happens?
they rotate another 180 degrees counterclockwise
what is the total degrees of rotation the intestines undergo
270 degrees
where does the cecum end up after intestinal rotation
lower right
where does the proximal end of the intestine end up after rotation
upper left part of abdominal cavity
goes back first
Meckle’s Diverticulum
persistence of vitelline duct
about 50 cm from ileocecal valve
what organs are secondarily retroperitoneal
2nd and 3rd parts of duodenum
head and body of pancreas
ascending colon
descending colon
midgut-hindgut transition (where does it occur)
2/3 of the way through the transverse colon near the left colic (splenic) flexure
midgut-hindgut transition (where does it get blood)
superior and inferior mesenteric arteries via the marginal artery of Drummond
cloaca (what is it and where)
part of hindgut
just proximal to the cloacal membrane
the cloaca is divided into what?
urogenital sinus (anterior) anorectal canal (posterior)
what divides the cloaca
growing urogenital septum between the hindgut and allantois
proctodeum (what is it)
an indentation of the body wall
forms distal opening of tube as septum grows
what happens to the proctodeum as the septum grows
pushes inward toward the anorectal cannot form the distal opening of the tube
fully formed anal canal is derived from what
cloaca (part of embryonic hindgut)
proctodeum (part of body wall)
the separation of the two region of the anal canal is called what?
the pectinate line
below the pectinate line where does the anal canal receive blood and innervation from?
branches of internal iliac artery
innervated by spinal nerves
above the pectinate line where does the anal canal receive blood and innervation from?
inferior mesenteric artery
autonomic nerves
what about the anal canal is important in understanding a variety of clinical conditions from rectal cancer to hermorrhoids
knowing about dual innervation, blood supply, and lymphatic drainage
