Thorax 6 - Development of Heart and Great Vessels Flashcards
By what day in embryonic development is a heart required to drive circulation?
Day 18
From which embryonic layer does the heart originate?
Mesoderm
Why is the heart based slightly on the left of the thorax?
The 2 ends fold slightly to the right, bringing the apex of the heart round to the left
From which veins does the venous end receive blood?
Cardinal
Vitelle
Umbilical
Describe two ways in which narrowing between atria and ventricles ensues.
Kink in the tube during folding of the early heart
Endocardial cushions
What does the 1st aortic arch form?
Maxillary arteries
What does the 3rd aortic arch form?
Common carotid arteries
What does the left 4rd arch form?
Aortic arch
What does the right 4th arch form?
Right subclavian artery
What does the left 6th arch form?
Pulmonary trunk & ductus arteriosus
What does the right 6th arch form?
Contributes to the pulmonary trunk
Which nerve can be impinged?
Left recurrent laryngeal nerve
The trip-laminar disk forms by week 3. What are the 3 layers?
Ectoderm
Mesoderm
Endoderm
How long is the embryo by week 3?
1.5mm
What does the heart tube form from and where does it form?
Angiogenetic clusters
Mesoderm
When does cephalon-caudal and lateral folding begin?
Day 18
When does looping and folding begin?
Day 22
How does the heart end up on the left side of the body?
The two ends of the heart tube fold towards each other and slightly to the right. This pushes the apex out to the left and rotates slightly so that the right side of the heart is slightly more anterior
During cephalon-caudal folding, what do each of the germ layers contribute?
Ectoderm: visceral pericardium
Mesoderm: cardiac muscle
Endoderm: endothelial lining
What is the name given in the case that the heart folds slightly to the left as opposed to the right, pushing the apex right?
Dextrocardia
At 28 days, how large is the embryo and what developments have there been with the heart?
5mm
Heart pushes into the pericardial sac
Ventricles begin to trabeculate
The venous end receives inflow from which veins?
Cardinal
Umbilical
Vitelle
Where do the atria bulge from either side?
Bulbus cordis
What do the proximal, middle and distal parts of the bulbus cordis form respectively?
Proximal: RV
Middle: outflow of ventricles
Distal: PT & aorta
Why are cranio-facial and cardiac abnormalities commonly linked?
Neural crest cells are involved in both cranio-facial development and cardiac development
I cardiac development, what do the neural crest cells form?
Endocardial cushions
What do enlargements of the endocardial cushions form?
Interatrial septum
Membranous part of the interventricular septum
AV valves (tricuspid & mitral)
Formation of the PT & Aorta from the truncus arteriosus
What structure divides the heart into left and right?
Endocardial cushions
What are neural crest cells used to grow?
Septum primum
What structure lies underneath the septum primum?
Ostium (foramen) primum
Holes developing create an ostium secundum. How are these holes ‘filled’?
Formation of a septum secundum to seal the ostium secundum
Which side does the septum secundum lie on with regard to the position of the septum primum?
RHS
What can atrial septal defect lead to?
Significant shunting from left to right
When is the formation of the interventricular septum said to be complete?
End of week 7
Where doe left and right ridges of endocardial cushion form?
Conus
What is the conotruncal septum?
The result of the left and right tranquil ridges spiralling around each other
An extension of which endocardial cushion grows and proliferates to become the muscular portion of the IVS?
Inferior AV cushion
What closes the interventricular foramen completely?
Membranous part of the interventricular septum
How do the mitral and tricuspid valves, chordae tendinae and papillary muscles form?
Endocardial cushion growth and cavitation
How do the aortic and pulmonary valves form?
Hollowing of the endocardial tubercles
What is the cause of aortic coarctation?
Abnormality in the aortic media and intimal proliferation
In the case of an aortic coarctation, which pulse in particular will be weak upon palpation?
Femoral
From which nerve does the recurrent laryngeal originate?
Vagus nerve
Which structures does the LRLN hook around?
6th arch
Ductus arteriosus / Ligamentum arteriosum
IN THORAX
Which structures does the RRLN hook around?
4th arch
Subclavian artery
NOT IN THORAX
