Great Vessel Embryology Flashcards
what are PA’s outgrowths of? what forms within them?
outgrowths of head and neck mesenchyme
aortic arches thru vasculogenesis and angiogenesis
what gives rise to the aortic arches?
aortic sac (expansion at distal truncus arteriosus)
what do the aortic arches connect?
aortic sac and dorsal aorta
what is the general structure of this primitive formation?
anterior- aortic sac
aortic arch
posterior- dorsal aorta
(most posterior- amniotic cavity)
how many aortic arches form?
six!
after the primitive vasculature forms, how does the adult formation take place? (three things)
- hypertrophy of some vessels
- addition of new vessels (external carotid and distal part pulmonary artery)
- loss of vessel segments
where do the dorsal aortas fuse and what direction do they continue to grow?
fuse at T4 level and grow caudually
how are the aorta and pulmonary artery formed/separated?
aorticopulmonary septum divides the truncus arteriousus into them
how do intersegmental arteries form? between what? what do they connect to?
via vasculogenesis within the paraxial mesoderm
somites
dorsal aorta’s
what adult vessel do the longitudinal anastomses of the cervical intersegmental arteries form?
vertebral arteries
(connections with the dorsal aorta disappear)
what do the 7th intersegmental arteries form?
L- subclavian artery
R- portion of subclavian artery
what adult vessels do the anastomses between the thoracic intersegmental arteries form?
internal thoracic arteries
what 2 adult vessel do the thoracic intersegmental arteries form?
- posterior intercostal arteries (proximal part in between the dorsal aorta and internal thoracic)
- anterior intercostals (distal part after internal thoracic)
what 2 adult structure do the lumbar intersegmentals form?
- epigastric artery
- (internal ?) iliac artery
what happens to AA 1 and 2?
they disappear
part of 2 becomes stapedial arteries
which AA is main feeder to head?
AA 3
what 3 adult vessels does AA 3 form?
- common carotid
- proximal part of internal carotid (remainder comes from dorsal aorta)
- external carotid- thru sprouting
what 4 things give rise to the adult aorta? what parts does each form?
- aortic sac- part 1
- left AA 4- part 2 (adult aortic arch)
- left dorsal aorta proximal to 7th intersegmental artery- part 3
- left dorsal aorta distal to 7th intersegmental artery- part 4
what insures the left AA 4 connects to the left ventricle?
spiraling of outflow tract
what 3 things forms the right subclavian artery and what parts?
- Right AA 4- proximal part
- dorsal aorta
- 7th segmental artery- distal part
what happens to AA 5?
never forms
how are the pulmonary arteries formed? what do they grow into?
each one is formed from proximal part of right AA 6 and aortic sac
grows into mesenchyme of lungs
what happens to the distal part of right AA 6?
dissappears (loses connection with right dorsal aorta)
what causes right recurrent laryngeal nerve to hook under the right subclavian artery?
regression of right AA 6
why does the left recurrent laryngeal arch stay hooked under distal left AA 6?
ductus arteriosus (later forms ligamentum arteriosum)
what is the carotid duct? what happens to it?
portion between AA 3 and AA 4
disappears
at what part does the right dorsal aorta disappear? what happens when it does?
after 7th intersegmental artery
fuses with left dorsal aorta to form descending aorta and abdominal aorta
what are the vitelline arteries and what do they eventually supply?
vessels that supply yolk sac
will eventually supply GI vasculature
what are the umbilical arteries (intially)?
paired ventral branches of dorsal aorta that connect to the placenta and also supply the bladder
what causes the proximal part (connection with dorsal aorta) of the umbilical arteries to disappear?
the new connection made between the 5th lumbar intersegmental arteries and distal umbilical arteries
what happens to the distal part of the umbilical artery after birth?
becomes medial umbilical ligaments
what happens the the proximal part of the umbilical arteries (the 5th intersegmental arteries) after birth?
become the iliac vessels (which are still referred to as the umbilical arteries in the adult)
what branches off of the umbilical arteries in the adult and what do they supply?
superior vesicular arteries that supply the bladder
how does oxygen rich blood get to the fetus heart?
thru the umbilical vein (thru placenta) and travels up the IVC to the RA
how does the oxygen rich blood bypass the liver (since IVC runs thru it)?
ductus venosus
what happens to the oxygenated blood once it enters the RA?
majority passes into LA thru foramen ovale
smaller portion goes into RV
where does deoxygenated blood from the fetus head, neck, and lungs travel?
via SVC and enters the RV
where does blood from the RV go?
90% into the descending aorta via ductus arteriosus
10% into lungs
what areas of the fetus recieve the highest oxygen content and why?
head, neck, heart, and upper limbs because they get it from the ascending aorta
what happens to the blood from the descending aorta?
travels to the lower limbs and either back up through the liver (where its oxygenated from the ductus venosus?) OR exits thru the placenta
how does the ductus arteriosus close after birth normally?
prostagladins keep it open as a fetus. once baby is born, drop in maternal prostagladin level along with an increase in endothelin from babys lungs causes smooth muscle contraction of the DA, which should cause it to close.
what happens if the ductus arteriosus does not close after birth?
since blood pressure in the aorta is higher than pulmonary artery, blood will keep re-entering the lungs through the DA. this causes extra work for LV which leads to hypertrophy. also leads to pulmonary resistance (and eventually congestion) and eventually heart failure (in which you’ll start to hear a murmur)
what increases the risk of patent ductus arteriosus?
maternal rubella during early pregnancy
what causes coarctation of the aorta? what are the two types? which is more serious? what population is this common in?
narrowing of the aortic lumen below left subclavian artery (due to thickening of aorta wall).
- postductal (after DA/ AA 4/ subclavian artery)- blood can still get thru body via anastomses/collateral circulation of the intercostal and intersegmental arteries
- preductal (after patent DA)- DA must remain open or else baby gets no blood to body and usually dies
what is abberant origin of subclavian? what does can it lead to?
right AA 4 and proximal dorsal aorta are obliterated so the right dorsal aorta and right 7th segmental are the only parts to form the right subclavian artery. since they now have to reach further down to get to the upper limbs, they have to cross the esophagus. this can lead to dysphagia and dyspnea but is often asymptomatic.
what is double aortic arch?
right dorsal aorta does not disappear which forms a vascular ring and can lead to strangulation of trache and dysfunction of esophagus
what is right aortic arch?
abnormal disappearing of left AA 4 and left dorsal aorta. right side must reach over to compensate which can compress structures and cause dysphagia and dyspnea
what is interrupted aortic arch?
what syndrome is it seen in?
(like abberant right subclavian) both AA 4 disappear. this causes low blood oxygen in the subclavian arteries so the DA must remain open and the aortic trunk must supply common carotid arteries. it’s life threatening
seen in DiGeorge syndrome
what is the blood flow of the vitelline veins?
blood from yolk sac–> sinus venosus–> passes thru septum transversum (where its surrounded by liver primordia)–> empties into sinus horn
what do the vitelline veins intially form as the liver grows?
vascular plexus known as hepatic sinusoids
what does the proximal portion of right vitelline vein form first and then the adult structure after?
first the hepatocardiac channel and then the terminal part of inferior vena cava
what happens to the proximal part of left vitelline vein? inferior part?
forms left hepatocardiac channel but then disappears
inferior part contributes to portal, splenic, superior & inferior mesenteric veins
what happens to umbilical veins?
left umbilical vein connects to sinusoids (right disappears)
how does ductus venosus form? what keeps it open thru pregnancy?
starts with relationship between left umbilical vein and hepatic sinusoids but then the umbilical veins dump it for the hepatocardiac channel
prostagladins
what 2 things does the ductus venosus become after birth?
ligamentum teres and ligamentum venosum
what vein is the early drainage system for fetus?
anterior and posterior cardinal veins. they form common cardinal veins (right side drains head and neck) which then empties in sinus horn
what does the anastomosis between the right and left anterior cardinal veins form and what happens after?
left brachiocephalic vein
left cardinal vein disappears and forms coronary sinus
what does the right common cardinal vein form? what can happen if this is abnormal?
SVC
SVC will drain into coronary sinus instead of the heart directly
what 2 parallel vessels does the posterior cardinal vein connect to? what do they form?
- subcardinal veins- forms veins associated with kidneys, gonads, and abdominal IVC
- supracardinal veins- forms parts of IVC and azygos vein
posterior cardinal disappears
