Transcript heart tube and pericardiumt

The CVS is the First major
system to function in the
embryo.
The primordium of the 
heart Begins at (18)
days.
It appears as: 
Aggregation of Splanchnic
Mesenchymal cells in the
Cardiogenic Area (ventral
to the pericardium).

The cells arrange 
themselves to form:
Two Longitudinal
Cellular Cardiac
Primordia.
This is under the 
influence of the
embryonic endoderm.
The cords canalized
and become thin
walled.
As a result of lateral
folding:
The tubes approach
each other and
begin to fuse.



Fusion of the tubes 
begin:
At the Cranial end of
the developing heart.
It extends Caudally.
A Single Endocardial
Tube is formed.



The First Beats are
detected at:
22- 23 Days. 
Blood Flow: 
Starts during the 
4th week.
This can be 
detected by
Doppler
ultrasonography.

It is part of the 
Intraembryonic
Celomic Cavity.
It lies over the Horse
Shoe –Shaped
Cardiogenic area.

The heart and 
pericardial cavity
come to lie:
Ventral to the 
foregut.
Caudal to the 
oropharyngeal
membrane.
This is a result of
head folding.

The cardiac tube is 
attached to the dorsal
side of the pericardial
cavity by
Dorsal Mesocardium. 
Ventral Mesocardium.
is Never formed.

Transverse Sinus: 
It is between the right
and left sides of the
pericardial cavity.
It is formed by: 
Degeneration of the 
Central part of the
Dorsal Mesocardium.

Endocardium: 
It is the Endothelial tube. 
Primordial Myocardium: 
It is the Splanchnic 
Mesoderm surrounding the
pericardium.
Cardiac Jelly: 
A gelatinous layer which 
separates the two.
Epicardium : 
Derived from cells in the 
external surface of the sinus
venosus.
It elongates and 
forms
Constrictions and 
Dilatations :
Truncus arteriosus. 
Bulbus cordis. 
Ventricle. 
Atrium. 
Sinus venosus. 
The Bulbus Cordis and 
Ventricle grow faster
than the others.
The cardiac loop bends 
upon itself.
The Cranial part bends: 
Ventrally, Caudally and 
to the Right.
The Atrial portion 
shifts :
Dorso Cranially and to 
the Left.
It is U-shaped. 
It has : 
Cranial Arterial End: 
Truncus Arteriosus. 
Aortic sac. 
Aortic Arches. 
It is fixed through the
pharyngeal arches.
Caudal Venous End 
It is fixed to the 
Septum Transversum.

A separate chamber. 
It opens into: 
The center of the 
dorsal wall of the
primitive atrium.
It has: 
Right and Left Horns of
the same size.

Each Horn receives (3) 
Veins:
1. Common Cardinal 
(from the embryo).
2. Umbilical (from the 
placenta).
3. Vitelline (from the 
yolk sac).
The Sinoatrial 
Orifice moves to
the Right
Because of: 
Obliteration of the
following veins:
Right Umbilical. 
Left Vitelline. 
Left Common 
Cardinal.

The left horn 
becomes :
Coronary Sinus. 
The right horn: 
Incorporated into
the Right Atrium.
It has: 
Smooth part: 
Incorporated from Sinus 
Venarum
Rough trabeculated part: 
Derived from the 
primordial atrium.
The two parts are 
demarcated by
The Crista and Sulcus 
Terminalis (internally and
Has right and left 
venous valvular folds
(venous valves).
Right Valve: 
Cranial part : Crista 
Terminalis
Caudal part : valves of
Coronary Sinus and
IVC.
Left Valve : 
Incorporated into the
Interatrial Septum.

The Rough 
Trabeculated Left
Auricle:
From the 
primordial atrium.
The smooth part: 
From incorporation
of the primordial
Pulmonary Vein.
The (4) pulmonary
veins are formed
from:
Gradual 
incorporation of 
the pulmonary vein
and its main
branches into the
wall of the
expanded atrium.
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