embryology Flashcards
what is the embryonic disk ?
the interface between the amniotic sac and the yolk sac
whata are the layers of the embryonic disk ?
ectoderm
mesoderm
endoderm
where does the GI tract originally come from ?
endoderm
where does the connective tissue and the muscles of the GI tract come from (surrounding structures) ?
from the mesoderm
where does the spleen come from ?
mesoderm
what is the blood supply associated which of these sections :
foregut
midgut
hindgut
foregut : celiac trunk
midgut : SMA
Hindgut : IMA
what are the different derivatives of the foregut, midgut and hindgut ?
foregut : mouth to the ampulla of vater
midgut: ampulla of vater until transverse colon
hindgut: transverse colon to rectum
what is the mesentry made up of ?
holds everything in place
double layer of peritoneum
what is the difference between intraperitoneal and retroperitoneal organs ?
intraperitoneal are enclosed by the mesentry
retroperitoneal only have the mesentry on their anterior surface and lie posterior against abdominal wall
the mesentery comes from ?
mesoderm
what are the two types of mesentry ?
dorsal mesentry
ventral mesentry
where is ventral mesentry found ?
bottom oesophagus
stomach
upper duodenum
where is the ventral mesentry derived from ?
septum transversum ( mesenchyme tissue)
what two structures are derived from the ventral mesentry ?
lesser omentum - connects stomach and duodenum from the liver
falciform ligament - connects the liver to the anterior abdominal wall
what are thw two types of omentum ?
lesser and greater
greater omentum - hangs from greater curvature of the stomach
lesser - between stomach and liver
what is the greater omentum formed from ?
mesogastrium
what organ buds off from the foregut ?
the lungs called the respiraatory diverticulum
what seperates the respiratory diverticulum from the oesophagus ?
the tracheo oesophageal septum
what happens if there is abnormal development in the tracheo oesophageal septum development and how does it happen ?
esophageal atresia happens
this happens when the septum deviated posteriorly
what are the three forms of esophagela atresia ?
EA with TEF - most common
pure EA
H type EA
what are the clinical features of esophgeal atresia ?
polyhydraminous ( baby cant swallow the amniotic fluid )
drooling , choking and vomiting when the baby is born
a NG tube cannot be passed
what are the findings associated with tracheo oesophageal fistulas ?
gastric distention ( air in stomach )
as well as respiratory distress caused by aspiration pneumonia due to reflux
what is the treatment and prognosis of EA ?
surgical repair
some residual dismotilyty
what is physiologic herniation and when does it happen ?
on the 6th week of development a normal type of herniation occurs through the umbilical cord
reduction of this hernia happens by week 12
what happens if physilogic herniation persists ?
persistence results in omphalocele
intestines are outaide of the body covered by membrane
if the liver is found to be in the sac of the omphalocele what is this an indication of ?
failure of the lateral embryonic folds
what are the intestines and midgut in omphalocele covered by ?
peritoneum
happens through the umbilical cord
what are the genetic defects associated genetic defects ?
trisomy 21 ( down syndrome)
trisomy 18 ( edwards syndrome )
trisomy 13
what are the associated conditions with omphaocele ?
congenital heart defects
orofacial clefts
neural tube defects
what is the difference between omphalocele and gastroschisis ?
gastrochisis the herniation happens through the a paraumbilical abdominal wall defect
not covered by peritoneum as with omphalocele
what is the main problem associated with gastroschisis ?
poor GI function
what is physiologic rotation of the midgut and what is the normal positioning it ends up in ?
the bowel rotates in week 6-7 around the SMA
cecum in the right lower quadrant
what are the problems associated with malrotation of the gut ?
obstruction
volvulus - wraps around the SMA
left sided colon - anatomic variant
what is the presentation of volvulus ?
vascular compromise causes ischemia and obstruction
hence the vomiting and sepsis
what is the vitelline duct ?
like a connector between the yolk sac and the intestines , should disappear during development week 9
what are the anomalies associated with the vitelline duct ?
meckels diverticulum ( most common)
cysts polyps
what type of diverticulum is meckels diverticulum ?
true diverticulum contains all layers of the bowel
what are the contents of meckels diverticulum ?
contains all layers of the bowel
often contains gastric tissue
ectopic gastic tissue
what is the rule of 2 associated with meckles diverticulum ?
2 % of the population
male to female ratio is 2:1
within 2 feet of the ileocecal valve
usually 2 inches in size
how is a diagnosis of meckels made and what is the treatment ?
technetium scan
capsule endoscopy
surgery is the treatment
what are the other vitelline duct anomalies ?
cyst
sinus - cavity behind umbilicus
persistent duct - intestinal discharge from the umbilicus
foetus with atresia or stenosis ?
mother has polyhydraminous
what is the cause of atresia ?
failure of recanalization
what is the associated genetic disorder with duodenal atresia ?
down syndrome
what is seen on imaging with duodenal atresia ?
double bubble sign
what is the pathology associated with jejunal ileal colonic atresia ?
vascular disruption causing ischemic necrosis
what is seen on imaging of jejunal ileal colonic atresia ?
apple peel atresia
what is the presentation of pyloric stenosis ?
first born boys are more likely
projectile vomiting non bilious vomiting
olive palpable mass
what is the blood supply of the spleen ?
celiac trunk
