Cardiovascular Embrylogy Flashcards
What effect does the embryo folding have on development of the heart?
Lateral fold = creates heart tube
Cephalocaudal fold = bring tube into thoracic region
What are the 6 parts of the primitive heart tube?
Aortic roots Truncus arteriosus Bulbus cordis Ventricle Atrium Sinus venosus
When does the heart start looping?
Day 23
Why does the heart start looping?
Tube elongates and runs out of space
How does the heart tube loop?
Bulbis cordis moves forward, down and right
Primitive ventricle moves back, up and left
What space does the heart tube looping form?
Transverse pericardial sinus - arteries in front of veins
What initially receives in flow to the primitive heart?
Sinus venosus - via right and left sinus horns
How does the right atrium develop?
Left sinus horn receded to form coronary sinus
Right sinus horn enlarges and is absorbed into growing right atrium
How does the left atrium develop?
The four pulmonary veins are incorporated into the left atrium
What space is created by the left atrium development?
Oblique pericardial sinus
How does the arterial system begin to develop?
Bilateral symmetrical system of arched vessels = aortic arches
How many aortic arches are there?
5 - numbered 1, 2, 3, 4, 6
What is derived from the 1st aortic arch?
Maxillary artery
Hyoid artery
Stapedial artery
What is derived from the 2nd aortic arch?
Maxillary artery
Hyoid artery
Stapedial artery
What is derived from the 3rd aortic arch?
Common carotid artery
Part of proximal internal carotid
What is derived from the 4th aortic arch?
Right = subclavian artery
Left = part of aortic arch
What is derived from the 6th aortic arch?
Right = R pulmonary artery
Left = L pulmonary artery + ductus arteriosus
What nerve is associated with the 6th aortic arch?
Recurrent laryngeal nerve
What happens to the right recurrent laryngeal nerve?
Initially hooks around 6th arch
Distal part of arch disappears
Moves up to hook around 4th arch
What happens to the left recurrent laryngeal nerve?
Hooks around 6th arch
Distal part of arch persists as ductus arteriosus
Nerve remains in position
How is the heart split into right and left channels?
Endocardial cushions expand and divide the heart
How are the atria divided?
Septum primum grows down towards fused endocardial cushions
Ostium primum = hole before septum fuses with cushions
Before ostium primum closes, ostium secondum appears in septum primum
Crescent shaped septum secondum grows next to septum present
Hole in septum secondum = foramen ovale
How are the ventricles divided?
Muscular portion of the septum grows up from floor to endocardial cushions
Small gap remains
Gap is filled by membranous portion
How is the outflow divided?
Endocardial cushions in truncus arteriosus grow into spiral septum
