6. EMBRYOLOGY : CVS
• Angiogenic clusters form horseshoe shaped plexus of blood vessels
• Anterior central part of plexus : Cardiogenic area
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7. EMBRYOLOGY : CVS
Heart Development
• Develops from splanchnic mesenchyme in cardiogenic area.
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14. PRIMITIVE HEART
• Heart tube elongates & bends
• Cephalic portion : bend in ventral & caudal direction & to right
• Caudal portion : bends to left
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18. EMBRYOLOGY : CVS
Sinus Venosus
• Maintain paired condition longer
than any other portion of heart
tube
• Each horn receives the vitelline v,
umbilical v, common cardinal v
ACV: Anterior cardinal vein
PCV: Posterior cardinal vein
UV : Umbilical vein
VIT: Vitelline vein
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19. EMBRYOLOGY : CVS
Sinus Venosus
Sinus venosus receives:
• umbilical veins from the chorion.
• vitelline veins from the yolk sac
• common cardinal veins from the embryo.
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20. EMBRYOLOGY : CVS
Sinus Venosus
Inferior portion of right sinus
develops into 2 parts:
• Valve of inferior vena cava
• Valve of coronary sinus
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21. EMBRYOLOGY : CVS
Sinus Venosus
• Wk 4 consist of small transverse
portion & L & R sinus horns
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24. EMBRYOLOGY : CVS
Sinus Venosus
• At 1st communication between sinus & atrium is wide
• With obliteration of the left umbilical vein , the left sinus
horn loses its importance
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25. EMBRYOLOGY : CVS
•
Sinus Venosus
develops a left horn which becomes the coronary sinus & a right horn which will be incorporated
into right atrium
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26. EMBRYOLOGY : CVS
Sinus Venosus
Remnant of the left sinus venosus :
• Oblique vein of left atrium
• Coronary sinus
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30. EMBRYOLOGY : CVS
• Intro to atrium & sinus
• Atrium & sinus venosus come to lie dorsal to bulbus cordis, truncus arteriosus &
ventricle
• At the same time, heart invaginates into pericardial cavity
• Dorsal mesocardium which attaches it to dorsal wall of pericardial cavity degenerates &
forms tranverse pericardial sinus
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31. EMBRYOLOGY : CVS
Truncus Arteriosus
Truncus Arteriosus
• Continues caudally with bulbus
cordis
• Enlarges cranially to form aortic sac
from which aortic arches arise
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32. EMBRYOLOGY : CVS
• Enlarges cranially to form aortic sac
from which aortic arches arise
Truncus Arteriosus
33. EMBRYOLOGY : CVS
THE ATRIA
Fate of adult Left Atrium
• Formed by incorporation of primitive pulmonary veins
• As atrium enlarges, parts of vein & its branches absorbed
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34. EMBRYOLOGY : CVS
•
Primitive pulmonary vein & its 4 main branches become partially incorporated into left atrium = 4
pulmonary veins.
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35. EMBRYOLOGY : CVS
Result
• 4 pulmonary veins entering adult left atrium
• Smooth walled part of left atrium derived from absorbed pulmonary vein tissue
• Left auricle derived from primitive atrium
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36. EMBRYOLOGY : CVS
Development of the smooth-walled portions of the right and left atrium.
Both the wall of the right sinus horn (blue) and the pulmonary veins (red) are
incorporated into the heart to form the smooth-walled parts of the atria.
37. EMBRYOLOGY : CVS
Cardiac septation
End of 4th wk, 2 mesenchymal cushions, the atrioventricular endocardial cushions,
appear at the superior and inferior borders of the atrioventricular canal
In addition, 2 lateral atrioventricular cushions appear on the right and left borders of the
canal
40. EMBRYOLOGY : CVS
• End of 4th week, sickle shaped crest grows from roof of atrium : Septum
Primum
• Opening between septum primum & endocardial cushion: ostium primum
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41. EMBRYOLOGY : CVS
• Limbs of septum extend in direction of endocardial cushions
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42. EMBRYOLOGY : CVS
• Crescent shaped fold : septum secundum
• Never forms complete partition in atrial cavity
• Free concave edge overlaps ostium secundum
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43. EMBRYOLOGY : CVS
• Opening left by septum secundum : Oval foramen
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44. EMBRYOLOGY : CVS
•
Before birth foramen ovale allows blood to pass from right atrium into left atrium; reflux is
prevented by the valve. After birth foramen ovale normally closes by fusion of septum primum &
septum secundum.
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