Clinical Embryology Flashcards
What is Ectopia cordis and what causes it
condition where heart is partly or completely exposed usually on thoracic surface
results usually from failure of lateral folds to fuse in that region
What is Gastroschisis and what causes it
usually on right side, allows abdominal viscera to protrude into amniotic cavity
uncommon defect in ventral abdominal wall resulting from incomplete closure of lateral folds
What is pulmonary hypoplasia and what is the major cause of it
Lung underdevelopment
Congenital diaphragmatic hernia
What is a congenital diaphragmatic hernia and what usually causes it
Posteriolateral defects in diaphragm allowing herniation of abdominal viscera into thoracic cavity
failure of pleruoperitoneal membrane to fuse with septum transversum and or dorsal mesentery of esophagus
on which side is a congeneital diaphragmatic hernia almost always found
Left
The mesodermal structure lying caudal to the pericardial cavity after folding of the head region is the septum transversum primitive streak developing heart oropharyngeal membrane notochord
septum transversum
A newborn infant has a congenital diaphragmatic hernia, this results from defective formation of which structures Costodiaphragmatic recess dorsal mesentery of the esophagus lateral body wall pleuroperitoneal membrane septum transversum
Pleuroperitoneal membrane
failure to fuse with dorsal mesentery of esophagus and septum transversum
What is the most common abnormality of the lower respiratory system and what causes it
Tracheoesophageal fistual
iincomplete separation of the esophagus and trachea
What are tracheoesophageal fistulas usually associated with
esophageal atresia
What symptoms come with tracheoesophageal fistulas and esophageal atresia
polyhydramnios: excess amniotic fluid during pregnancy (not oligohydraminos which is too little)
excess salivation
regurgitation after feeding
abdominal distention after crying
inflammation of lungs
Why might you get inflammation of the lungs with tracheoesophageal fistulas and esophageal atresia
reflux of stomach contents into the lungs
Which of the following is often associated with a tracheoesophageal fistulas and esophageal atresia Unilateral agenesis of the lung Laryngeal atresia Unilateral pulmonary agenesis polyhydramnios during pregnancy congenital lung cysts
Polyhydramnios during pregnancy
because fetus is unable to swallow amniotic fluid which then accumulates because it is unable to pass to the fetal stomach and intestines for absorption
What is the first indication of lower respiratory tract development in the human embryo Bronchial bud laryngotracheal groove primary bronchus bronchopulmonary segment lung bud
Laryngotracheal groove
forms as an outgrowth from primitive pharyngeal floor during 4th week
Why would polyhydramnios occur during pregnancy with tracheoesophageal fistulas and esophageal atresia?
because fetus is unable to swallow amniotic fluid which then accumulates because it is unable to pass to the fetal stomach and intestines for absorption
Atrial Septal defects is the term for defects in formation of what 2 structures
septum primum and/or septum secundum
What causes a probe patent foramen ovale and what type of shunting does it allow
caused by incomplete adhesion of the foramen ovale valve with the septum secundum
Left to right shunting
What causes a patent foramen ovale and what type of shunting does it allow
Ostium secundum defects;
abnormal or excessive resorption of the septum primum or abnormal development of septum secundum
Left to right shunting
What causes a patent foramen primum and what type of shunting does it allow
Ostium primum defects involving deficiencies in the endocardial cushion and atrioventricular septum formation
Failure of septum primum to fuse with endocardial cushions to fuse
In what group is a patent foramen primum more common
those with Down syndrome
What is the most common congenital heart defect
Ventricular septal defects
Where do most VSD’s occur
defects in membranous portion of the interventricular septum
What type of shunting do VSD’s allow and what can they cause
Left to right shunting of blood
Can result in pulmonary hypertension and possible cardiac failure
What is the key defect in tricuspid atresia and what does it result in
complete occlusion of the right atrioventricular opening
results in cyanosis
What defects always accompany tricuspid atresia
underdeveloped right ventricle and usually ASD and VSD
What causes Persistant Truncus arteriosus
failure of the aorticopulmonary septum to develup and divide the truncus arteriosus into aorta and pulmonary trunk
What defect is always associated with Persistant Truncus arteriosus and why?
VSD because the membranous interventricular septum normaly merges with the aorticopulmonary septum
How does blood shunting occur with Persistant Truncus arteriosus
OVERALL RIGHT TO LEFT
VSD thats present with it allows some left to right
but Persistant Truncus arteriosus overwhelms it with right to left ( allowing blood to bypass the lungs)
How do you end up with transposition of the great arteries
when the aorticopulmonary septm fails to follow a spiral course when dividing the truncus arteriosus and bulbous cordus
What other defects are also usually associated with transposition of the great arteries
ASD and VSD and possibly patent ductus arteriosus
How does blood shunting occur with transposition of the great arteries
Overall Right to left
ASD and VSD permit soome left right shuntin
but most deoxy blood returning to right atrium bypasses the lungs and enters the aorta
What is the major cause of cyanotic heart disease in newborns
Transposition of the great arteries
What causes Tetralogy of Fallot
Unequal division of the bulbus cordis with anterior displacement of the aorticopulmonary septum
What 4 things result from tetralogy of Fallot
pulmonary stenosis
overriding aorta
VSD
and hypertrophy of the right ventircle
What is the overall shunting in Tetralogy of Fallot
Right to left
of poorly oxygenated blood (thus cyanosis clinical sign)
What characterizes Coarctation of the aorta
constriction of varying length and usually occuriing directly opposite to the ductus arteriosus
What is Coarctation of the aorta typically associated with
Turners syndrome
When do you have Patent ductus arteriosus and what shunt does it cause
when the vessel fails to close and form ligamentum areriosum
Left right shunt
In what cases is Patent Ductus areriosus commonly found
MATERNAL RUBELLA INFECTION DURING EARLY PREGNANCY
Premature infants and those with persitent hypoxia
The fetal left atrium is primarily derived from coronary sinus endocardial cushion primitive atrium primitive pulmnoary vein sinus venosus
Primative pulmonary vein
Which of the following defects is associated with tetralogy of Fallot Aortic coarctation patent foramen ovale pulmnoary stenosis tricuspid atresia Patent foramen primum
Pulmnoary stenosis
also see overriding aorta VSD and right ventricular hypertropy
What causes stenosis (narrowing) of the esophagus and where in the esophagus does it normally occur
incomplete recanalization of the lumen
usually occurs in distal third of esophagus
What 2 ways can atresia (closing) of the esophagus occur and which is more common
incomplete recanalization of the lumen or
incomplete seperation of the trachea and esophagus
2nd is most common
What causes hypertrophic pyoric stenosis and what are the symptoms in an infant?
Thickening of the circular pyloric musculature (instead of incomplete recanalization)
stomach markedly distended and infant has projectile vomiting
Where does stenosis of the duodenum usually occur
Horizontal (3rd) and ascending (4th)
Where does atresia of the duodenum almost always occur and sometimes occur?
Almost always in descending (2nd)
sometimes in horizontal (3rd)
Atresia arises in 1/3rd of individuals with what
Down syndrome
What symptom characterizes duoodenal obstruction
vomit containing bile
What causes Extrahepatic biliary atresia and where does it normally occur
incomplete recanalization of hepatic ducts
usually at or superior to porta hepatis
What symptom characterizes Extrahepatic biliary atresia
Infant develops jaundice soon after birth
What can cause an anular pancreas and what does it cause
bilobed ventral pancreatic bud grows and encircles the duodendum CAUSES OBSTRUCTION
What accounds for 50% of intestinal obstrections
stenosis and atresia of the ileum
What causes most ileal atresias
infarctions from twistin of the intestines
What is an omphalocele and what causes it
extrusion of abdominal viscera in the proximal umbilical cord
caused by failure of intestines to normally return to abdominal cavity
What other defects is an Omphalocele associated with
Cardiac and neural tube defecs
How does an Omphalocele differ from an umbilical hernia
umbilical hernia, intestines return to abdominal cavity and then herniate through imperfectly closed umbilicus
Omphalocele they never return to abdominal cavity
How does an omphalocele differ from gastroschisis
Visera in an ophalocele are covered ny peritoneum and the amnion derived covering of the umbilical cord
What causes most anomalies of the intestine
incomplete gut rotation
What are 3 types of improper gut rotation
Non rotation (cecum in middle small on left)
mixed rotation ( small on left and middle colon transverse above and on right)
reversed rotation (normal layout but duodenum in front of transverse colon)
Which two improper gut rotations is Volvus (twisting) of the intestines associated with and what can it result in
Nonrotation and mixed rotation
can result in gangrene of bowls
What is an ileal (Meckel) diverticulum and what can happen to it
Rmnant of the proximal part of the omphaloenteric duct
can become inflamed and thus mimic symptoms of appendicitis
where is the ileal (Meckel) diverticulum attached and by what
can be connected to the umbilicus by an omphaloenteric fistula or a fibrous cord
What causes most anorectal anomalies
abnormal partitioning of the cloaca by the urorectal septum
What are 5 anorectal anomalies and which 2 usually present with fistula
imperforate anus anal agenesis (usually with fistula) anal stenosis anorectal agenesis (usually with fistula) rectal atresia
What makes up 2/3rds of anorectal defects
anorectal agenesis (with or without a fistula)
What is the most common cause of neonatal obstruction of the colon and what is it characterized by
Congenital megacolon (hirschsprung disease)
characterized by abnormal dilation of the sigmoid colon and rectum
What causes the dilation in Congenital megacolon (hirschsprung disease)
neural crest cells fail to migrate into the hindgut and form parasympathetic ganglia in the gut wall
what is characteristic of the affected bowl and the bowl proximal to it in Congenital megacolon (hirschsprung disease)
affected bowl has absence of peristalsis
proximal contains autonomic ganglia and consequently dilates
A 3 week old infant has a history of projectile vomiting. Vomit has no bile. Baby is constantly hungry but has not gained weight. Which explains the symptoms Esophageal atresia Ileal dierticulum Hypertrophic pyloric stenosis Tracheoesophageal fistula duodenal stenosis
Hypertrophic pyloric stenosis
narrowing of pyloric canal and obstruction to passage of food
blockage of duodeunum associated with vomit containing no bile
The embryonic midgut gives rise to which of the following duodenum liver sigmoid colon head of pancreas upper portion of anal canal
Duodenum
