Embryology 1 - Early Development of the CVS Flashcards
Where does the cardiogenic field lie?
At the cranial end of the embryo before folding occurs
How does CVS development begin?
A pair of endocardial tubes develops in the third week
What is the role of lateral folding?
Creates the heart tube
What is the role of cephalocaudal folding?
Brings the tube into the thoracic region
From cranial to caudal, what is the order of the segments of the primitive heart tube? (ALL THE BEST VAGINAS ARE SHAVED)
Aortic roots Truncus arteriosus Bulbus cordis Ventricle Atrium Sinus venosus
What causes bending of the heart tube?
Continued elongation
When does bending occur?
Day 23-28
How does the cephalic cranial portion bend?
Ventrally, caudally, right (forwards, downwards, right)
How does the caudal portion bend?
Dorsally, cranially, left (backwards, upwards, left)
What is the result of bending?
Places both outflow and inflow cranially, with inflow behind outflow
How does the atrium communicate with the ventricle?
Atrioventricular canal
What is the transverse pericardial sinus?
Space behind the outflow and in front of the inflow.
What is the sinus venosus?
Where the blood from the placenta, yolk sac and body drains into
How do the sinus horns develop?
Start equal sizes.
Venous return shifts to the right hand side so the left sinus horn recedes.
Enlarging right atrium absorbs the right sinus horn.
How does the right atrium develop?
From most of the primitive atrium and absorbs the right horn of the sinus venosus.
Receives venous drainage from body (vena cava) and heart (coronary sinus).
How does the left atrium develop?
From small portion of the primitive atrium and absorbs proximal parts of pulmonary veins.
Receives oxygenated blood from lungs.
How is the oblique pericardial sinus formed?
As left atrium expands and absorbs the pulmonary veins
How does the arterial system develop?
Begins as a bilaterally symmetrical system of arched vessels (5 arches labelled 1, 2, 3, 4, 6).
Undergo remodelling to create the major arteries leaving the heart.
What is the derivative of the 4th aortic arch?
Right - proximal part of right subclavian artery.
Left - arch of aorta
What is the derivative of the 6th aortic arch?
Right - right pulmonary artery
Left - left pulmonary artery and ductus arteriosus
