Embryology Flashcards
What is the CV system originate from?
splanchnic mesoderm
What are the 5 portions of the primitive heart?
truncus arteriosus Bulbus cordis ventricle atrium sinus venosus
What does the truncus arteriosus become?
pulmonary artery and aorta
What does the bulbus cordis become?
the right ventricle
What is the sinus venosus?
paired region into which the veins drain
What does the left sinus venosus become?
the coronary sinus
What does the right sinus venosus become?
it becomes incorporated into the right atrial wall
After formation of an endocardial tube - what occurs in development of the heart?
Forms an s-shaped curve
Truncus arteriosus –> bulbus cordis –> ventricle –> common AV opening –> atrium –> sinus venosus
What is the function of the truncus arteriosus in the embryonic heart?
common outflow tract
What is the function of the sinus venosus in the embryonic heart?
receives venous blood into the heart
How does the common atrioventricular become partitioned?
proliferation of the endocardial cushion and migration ventrally
Will eventually sit in the common area between the atria and ventricles
How are the atria partitioned?
Two separate septa are formed from dorsal atrial wall ventrally: septum primum and secundum - that grow to meet the endocardial cushion
What is the foramen primum? secundum?
Septum primum grows from dorsal atrial wall, obliterates pre-existing foramen primum
Foramen secundum develops through fenestrations of the first septum (dorsally within the atria)
What is the foramen ovale?
After the septum secundum grows ventrally (over top of the foramen secundum) - it will remain incomplete and the free edge forms the foramen ovale
What are the three stages of the interatrial foramen in the embryonic heart?
foramen primum
foramen secundum
foramen ovale
How are the embryonic ventricles partitioned?
Ventral –> dorsal growth of a muscular ridge from the central region of the common ventricle
How are the aorta and pulmonary trunk formed?
Truncus arteriosus partitioned in a spiral pattern to form the aorta and pulmonary trunk
What deformity occurs if the truncus arteriosus fails to develop?
Transposition of the great vessels: Aorta will remain connected to the right ventricle, and the pulmonary trunk to the left ventricle
What does the paired ventral aorta become?
brachiocephalic trunk
Which of the aortic arches regress without forming anything?
1, 2 and 5
Which of the aortic arches will become a important structure?
3, 4 and 6
What does the third aortic arch become?
Internal carotid artery and common carotid artery
External carotid artery buds from the third arch
What does the left fourth aortic arch become?
Arch of the aorta
What does the fourth right arch of the aorta become?
the right subclavian artery
What do the sixth embryonic aortic arches become?
pulmonary arteries
Right - ductus arteriosus
What is the purpose of the ductus arteriosus?
shunts blood from the pulmonary system into systemic circulation
What is the persistence of the ductus arteriosus called after birth?
PDA
Why does a PDA result in continuous shunting?
the aorta pressure is higher than the pulmonary artery in all stages –> continuous shunting into the pulmonary vasculature system.
What are the major embryonic veins?
Sinus venosus vitelline veins umbilical veins common cardinal veins cranial cardinal veins caudal cardinal veins: super and supracardinal veins
What embryonic veins will form the cranial vena cava and its major cranial branches (jugular)?
Each cranial cardinal will form the internal jugular vein
External jugular and subclavian veins bud from cranial cardinal veins
Caudal segment of right cranial cardinal vein and right common cardinal vein become right cranial vena cava
What forms the brachiocephalic vein?
What does this vessel do?
If this does not form appropriately - what congenital vascular abnormality occurs?
left cranial cardinal vein
Shunts venous blood from the left –> right into the CrVC
double cranial vena cava
What embryonic vasculature forms the cranial portion of the caudal vena cava?
Right subcardinal and right vitelline vein
What embryonic vasculature forms the caudal portion of the caudal vena cava?
supracardinal vein
What embryonic vessel becomes the azygos vein?
supracardinal vein, caudal and common cardinal veins of right side
What embryonic vessel becomes the portal vessel?
vitelline vein
What embryonic vessel forms the ductus venosus?
umbilical vein
How can portosystemic shunts form?
Persistent ductus venosus
Anastomosis between portal vein and CVC or azygos (not too unreasonable given all the patchwork that goes on).
Describe the major components of the fetal circulation?
Fetal CO2 is exchanged for maternal oxygen at the placent –> umbilical veins –> fetus –> ductus venosus (shunts blood from liver tot he heart) –> shunts that prevent blood from entering pulmonary circulation (foramen ovale, ductus arteriosus) –> aorta –> extremities, body –> umbilical arteries
How does a double aortic arch form?
Persistence of both dorsal aortic arches
Considered a type 4 vascular anomaly
What is the most common form of VRA?
PRAA - retention of 4th aortic arch - rather than the left 4th aortic arch forming the main aortic arch - the right will
How does an aberrant right subclavian form?
Bi-subclavian trunk - both subclavians have a common origin on the aberrant right aortic arch- the left has to cross over to reach the left side.
