The document summarizes the development of the heart and associated vessels in the embryo. It discusses the formation of the primitive heart tube and the divisions that form the four chambers. It describes the development of internal structures like the atrioventricular canal and septa. It also covers the formation of the aortic arches and branching arteries as well as the umbilical and cardinal veins. The development occurs through the fusion, division and remodeling of early heart structures in the embryo.

6. =DEVELOPMENT OF HEART (cardiac loop):-
[ 1 ]=External features of cardiac loop.
1*development of primitive heart tube.
2*development of cardiac contstrictions.
3*twesting of primitive heart tube.
[ 2 ]=Internal features of cardiac loop:-
1*Development sinus venosus.
2*Division of atrio-ventricular canal.
3*Development of primitive atria.
4*Development of primitive ventricle.
5*Development of bulbus cordis.
6*Development of truncus arteriosus.
[ 3 ]=Fetal circulation.
[ 4 ]=Congenital anomalies of heart.
=DEVELOPMENT OF ARTERIES:-
Development of aortic arches
DEVELOPMENT OF VEINS:-
1.UMBILICAL VEINS.
2.VETILLINE VEINS.
3.CARDINAL VEINS.

8. *It is meso-dermal in origin.
*From cardiogenic plate of Intra-embryonic
mesoderm. Lateral plate mesoderm
*which is formed of:-
1- Angio-blastic cells.
2- Myo-epicardial mantel ; that will give:-
1-Fibrous pericardium.
2-Myo-cardium.
ORIGIN OF HEART

9. Ectoderm
Mesoderm
Endoderm
Cardiogenic
plate

15. PROCESS
OF
DEVELOPMENT

16. [ 1 ]=External features
of cardiac loop.

17. • 1*development of primitive heart tube.
• 2*development of cardiac contstrictions.
• 3*twesting of primitive heart tube.

18. =Angio-blastic cells form clusters of cells.
=The central cells of these clusters:-
*are separated from the pripheral cells.
*will form W.B.Cs & R.B.Cs.
=The peripheral cells of these clusters :-
*will form the wall of blood vessels.

23. 1]=One will form of a pair of primitive heart tubes.
arranged in the parasagittal plane.
2]=Others will growe, elongate & branch.
to form network of blood vessels.
one end of this network:-
-where the blood leaves the network.
-will form veins.
the other end of this network:-
-where the blood enters the network.
-will form arteries.
the network in between the ends will form the
blood capillarie
These blood vessels in two types

26. =The two heart tubes will fuse with
each other giving single primitive
heart tube.
=One end of the tube is arterial
[for exit of blood]
=Other end of tube is venous
[for entering of blood]

32. = constrictions appear in heart tube.
= 1st constriction:-
*appears in primitive heart tube.
*dividing it into:-
1-Primitive ventricle : cephalic part.
2-Primitive atria : caudal part.
=2nd constrictions:-
*appear in the primitive ventricle.
*dividing it into:-
1-Primitive ventricle : caudal part.
2-Bulbus cordis. : consists of
-proximal1l3 -middle 1l3(conus cordis) -distal 1l3(Truncus
arteriosus): cranial partcontinous distally with
aortic sac.

36. =The primitive atria:-
*NO constriction.
*region where the veins drain become dilated and
forms sinus venosus.
=NOW , the heart tube consists of the
following 4 chambers:-
from caudal to cephalic
1*sinus venosus.
2*primitive atria.
3*primitive ventricle.
4*bulbus cordis. Divid into
- proximal 1l3 - middle 1l3(conus cordis) - distal 1l3(truncus
arteriosus).

39. =With further growth , elongation of heart tube.
=heart tube, becomes S-shaped and consists of:-
1*Right limb:-
-bulbus cordis.
2*Transverse limb:- primitive ventricle.
3*Left limb:-
-primitive atria.
-sinus venosus.
=At early stage, the heart and pericardium are
located in the neck later on , they descends caudally
to the thorax.

49. [ 2 ]=Internal features
of cardiac loop.

50. PROCESS
OF
DEVELOPMENT

51. *SITE
=caudal to primitive atria.
=in mesoderm of septum transversum.

53. *SHAPE
[in early stage of development]
1=BODY [CENTRAL PART]:-
-opens into posterior wall of primitive atria by sino-atrial orifice.
2=TWO HORNS [RIGHT & LEFT]:-Each one receives the following:-
Vitelline vein:-
*medial.
*carries unoxygenated blood from yolk sac.
Umbilical vein:-
*lateral.
*carries oxygenated blood from placenta.
Common cardinal vein:-
*the most lateral.
*carries unoxygenated blood from body wall.
*it is formed by union of :- anterior & posterior cardinal veins.

54. Left horn
Right horn Body
L.
V.
V.
R.
V.
V.
L.
U.
V.
R.
U.
V.
Yolk sac
Placenta
L.C.C.V.
R.C.C.V.
R.
A.
C.
V.
R.
P.
C.
V.
L.
A.
C.
V.
L.
P.
C.
V.

55. =Blood reaches right horn exceeds that of left horn
due to:-
1-development of liver on right side.
2-presence of anastmoses between left and right
cardinal veins shifting blood from left to right.
=Resulting in:-
1-Body :- reduced in size.
2-Right horn:- increases in size on expense of body.
3-Left horn :- reduced in size.
4-Sino-atrial orifice :-
=at first :- lies transversely.
=then :- vertical
=guarded by two valves :- right & left.
PROCESS OF DEVELOPMENT
[in late stages of development]

56. Left horn
Right horn Body
L.
V.
V.
R.
V.
V.
L.
U.
V.
R.
U.
V.
Yolk sac
Placenta
L.C.C.V.
R.C.C.V.
R.
A.
C.
V.
R.
P.
C.
V.
L.
A.
C.
V.
L.
P.
C.
V.

57. Left horn
Body
L.
V.
V.
R.
V.
V. L.
U.
V.
R.
U.
V.
Yolk sac
Placenta
L.C.C.V.
R.C.C.V.
R.
A.
C.
V.
R.
P.
C.
V.
L.
A.
C.
V.
L.
P.
C.
V.
Right
horn

60. 1=Body :- coronary sinus.
2=Right horn:- smooth posterior part of right atrium.
3=Left horn :- oblique vein of left atrium.
4=Sino-atrial valves:-
Right valve:- C. I. C.
upper 1/3 + septum spurium :- crista terminalis.
middle 1/3:- valve of I.V.C.
lower 1/3 :- valve of coronary sinus.
Left valve:- shares in formation of inter-atrial septum.
Upper end of both valves :- septum spurium.
*FATE & DERIVATIVES OF SINUS VENOSUS

63. Left horn
Right horn Body
L.
V.
V.
R.
V.
V.
L.
U.
V.
R.
U.
V.
Yolk sac
Placenta
L.C.C.V.
R.C.C.V.
R.
A.
C.
V.
R.
P.
C.
V.
L.
A.
C.
V.
L.
P.
C.
V.

64. Oblique vein
Coronary
sinus
L.
V.
V.
R.
V.
V. L.
U.
V.
R.
U.
V.
Yolk sac
Placenta
L.C.C.V.
R.C.C.V.
R.
A.
C.
V.
R.
P.
C.
V.
L.
A.
C.
V.
L.
P.
C.
V.
Posterior
Smooth part
Of
Rt. atrium

68. PROCESS
OF
DEVELOPMENT

70. *PROCESS OF DEVELOPMENT:-
=is divided into two canals right & left by:-
Dorsal A-V E.C.C.:- from dorsal wall of the canal.
Ventral A-V E.C.C.:-from ventral wall of the canal.
=Two cushions grow towards each others & fuses to form:-
septum intermedium.
*FATE & DERIVATIVES:-
1-Upper part of both halves:
absorbed into the corresponding atrium. [right & left]
2-Lower part of both halves:
absorbed into the corresponding ventricles. [right & left]
3-Septum intermedium:-
shares in formation of interatrial & interventricular septa
[SEE NEXT]
Is the canal connects the primitive atrium & primitive ventricle.

75. PROCESS
OF
DEVELOPMENT

76. 1. Partitioning of primitive atria.
2. Development of right atrium.
3. Development of left atrium.

77. **By inter-atrial septum:-
**developed by the following order:-
development of septum premium:-
=It arises from the roof of primitive atrium.
=arises as a sickle shaped septum.
=that grows towards septum intermedium.
=Its lower rim is separated from septum intermedium by
foramen premium.
=Finally, the septum premium fuses with septum intermedium
closing foramen premium.
=As soon as, the fusion occurs , the cranial end of septum
premium is rupture [break down ] forming foramen secondum.
=foramen secondum:-
*present between the cranial border of septum premium and
the roof of primitive atria.
*allows free passage of blood.
1*Partitioning of primitive atria

88. =It arises from the roof of primitive atrium.
=arises as a sickle shaped septum.
=on the right side of septum premium.
=It grows towards septum intermedium.
=Its lower rim begins to to overlap the foramen secondum.
=new passage of blood formed between the right and left atrium
is called foramen ovale.
= foramen ovale:-
*not a simple orifice.
*oblique passage for blood stream from right atrium to left atri.
*this passage passes between:-
1-lower edge of septum secondum & septum intemedium.
2-then between septum premium and septum secondum.
development of septum secondum

89. 1-septum premium.
2-septum secondum.
3-septum intermedium.
4-left valve of sino-atrial orifice.
5-neural crest. [some cells]
Inter-atrial septum develops from

90. Fate of foramen ovale
1-closed after birth.
2-due to fusion between septum
premium and septum secondum.
3-It will give the following derivatives:-
septum premium:- fossa ovalis.
septum secondum:-annulus ovalis.

91. 1-Rt. half of primitive atria :-rough anterior part.
2-Rt. horn of sinus venosus :- smooth posterior part.
3-Right half of atrio-ventricular canal [its upper part]
4-Interior of right atrium:-
1-fossa ovalis:-from septum premium.
2-annulus ovalis:- from septum secondum.
3-crista terminalis:- from upper 1/3 of Rt. sino-atrial v.
4-valve for I.V.C.:- from middle 1/3 of """"""""""""""".
5-valve of coronary sinus:-from lower 1/3 of """"""".
2*Development of right atrium

94. 1-Lt. ½ of primitive atria:- rough anterior part.
2-Lt. ½ of atrio-ventricular canal [its upper part]
3-Pulmonary vein [root and 1st division ] :-
[its posterior smooth]
resulting in four separate openings for the
pulmonary veins.
3*Development of left atrium

96. PROCESS
OF
DEVELOPMENT

97. 1. Partitioning of primitive ventricle.
2. Development of right ventricle.
3. Development of left ventricle.
4. Development of interior of ventricles.

98. **By inter-ventricular septum:-
**developed by the following order:
development of muscular part :-
=It is a larger antero-inferior part.
=arises as a sickle shaped septum.
=it arises from endocardium of the floor of primitive ventricle.
=it grows towards septum intermedium.
=Its upper rim is separated from septum intermedium by inter-
ventricular f.
development of membranous part:-
=It is derived from:-
dorsal A-V E.C.C..
ventral A-V E.C.C..
bulbar ridges [right & left]
=It will close the interventricular foramen.
1*Partitioning of primitive ventricle

101. =The infundibulum [smooth part]:-
*from antero-lateral portion of bulbus cordis.
=The rough part [papillary muscles, chorda tendinae,
trabecular carnae]
*right half of primitive ventricle.
2*Development of right ventricle

102. =The aortic vestibule. [smooth part]:-
*from postero-medial portion of bulbus cordis.
=The rough part [papillary muscles , chorda tendinae
, trabecular carnae]
*left half of primitive ventricle.
3*Development of left ventricle

103. =small cavities appear in the myocardium.
=unit together to form larger cavities.
=separating from each other by ridges
variable in size that project into the interior
of the ventricle.
=These ridges will differentiate into :-
1-trabeculae carnae.
2-papillary muscles.
3-chorda tendinae.
4*Development of interior of ventricles

105. PROCESS
OF
DEVELOPMENT

106. **By two bulbar ridges.
**developed by the following order:
1-right dorsal bulbar ridge.
2-left ventral bulbar ridge.
**These ridges grow toward each
other & unite together to form
bulbar septum.
*Partitioning bulbus cordis

108. 1-Antero-lateral portion:-
=forms infundibulum of right ventricle.
=gives origin to pulmonary trunk.
2-Postero-medial portion:-
=forms aortic vestibule of left ventricle.
=gives origin of to ascending aorta.
This septum divides the bulbus cordis into

111. PROCESS
OF
DEVELOPMENT

112. 1]=Four endocardial cushions:-
1-anterior.
2-posterior.
3-right .
4-left.
2]=Develop from the walls of
cephalic part of bulbus cordis at its
junction with truncus arteriosus.

114. 1*right & left cushions fuse with each
others to divide the orifice into:-
1-anterior [pulmonary] orifice.
2-posterior [aortic] orifice.
2*anterior & posterior cushions remain
separated.
3*each aortic & pulmonary orifices has
three cushions:-
FATE

116. AORTIC ORIFICE
PULMONARY ORIFICE
1-Two anterior & one
posterior.
2-as result of
rotation of aorta 45˚
3-It becomes:-two
posterior & one
anterior.
1-Two posterior & one
anterior.
2- as result of rotation
of pulmonary trunk 45˚
3-It becomes, two
anterior & one
posterior.

119. PROCESS
OF
DEVELOPMENT

120. **By two bulbar ridges.
**appears at the cranial part.
**developed by the following order:
1-right bulbar ridge. 2-left bulbar ridge.
**right bulbar ridge grows distally and to left.
**left bulbar ridge grows distally and to right.
**two bulbar ridges undergo 180˚spiraling .
**They finally fuse together forming spiral aortico-
pulmonary septum.
Partitioning truncus arteriosus

121. FATE
AT THE CRANIAL
PART OF TRUNCUS
ARTERIOSUS
AT THE MIDDLE
PART OF TRUNCUS
ARTERIOSUS
AT THE CAUDAL
PART OF TRUNCUS
ARTERIOSUS
1-septum lies
transversely.
2-It is divided into:-
a]=anterior part :-
ascending aorta.
b]=posterior part:-
pulmonary trunk.
1-septum lies
anteroposterior.
2-It is divided into:-
a]=right part :-
ascending aorta.
b]=left part:-
pulmonary trunk.
1-septum lies
transversely.
2-It is divided into:-
a]=posterior part :-
ascending aorta.
b]=anterior part:-
pulmonary trunk.

123. DEFINITION:-
*Is the circulation of blood
=between fetus and mother
=and through the fetus.

127. CONTENTS OF UMBILICAL CORD:-
FETAL CIRCULATION BEFORE BIRTH
*Early in embryonic life:
Two umbilical arteries:-[right & left]
-carry un-oxygenated blood.
-from fetus to placenta.
Two umbilical veins:-[right & left]
-carry oxygenated blood .
-from placenta to fetus.
*Later in embryonic life:-
Two umbilical arteries:-[right & left]
One umbilical veins:-
Which is left umbilical vein , the right one disappears.

130. PATHWAYS FROM LEFT UMBILICAL VEIN TO I.V.C. :
FETAL CIRCULATION BEFORE BIRTH
1*Long circuit:-
Small portion of blood passes in this circuit.
=flows From LT. umbilical vein To Lt. branch of portal vein.
=So, blood enters hepatic sinusoid :-where blood is mixed with
blood from vitelline vein. It flows From hepatic sinusoid To
hepatic veins, then To I.V.C.
Blood from left umbilical vein undergo two circuit

131. 2*Short circuit:-
Large portion of blood passes in this
circuit.
=flows From Lt. umbilical vein To
ductus venosus, then To I.V.C.

133. PATHWAYS FROM I.V.C. :-
1*The major portion of blood:-
=passes from Rt. atrium Through foramen ovale To Lt. atrium.
=In Lt. atrium, blood mixes with small amount of blood returing
from lungs through four pulmonary veins.
=passes From Lt. atrium through mitral valve To Lt. ventricle.
=passes From Lt. ventricle Through aortic valve To aorta and
branches of aorta.
=It supplies :- head & upper limb.
=Blood stream enters the right atrium guided by valve.
=Has two types:-

135. =is not pass to Lt. atrium and retained in Rt. atrium.
=In Rt. atrium, blood mixes with small amount of blood returing from
S.V.C. that comes from:-
1-head .
2-upper limb.
=passes From Rt. atrium Through tricuspid valve To Rt. ventricle.
=passes From Rt. ventricle Through pulmonary valve To pulmonary
trunk.
=blood in pulmonary trunk has two pathways:-
small amount passes to lung to supply it with mixed blood.
This is due to high resistance in pulmonary vessels due to non-
functioning lung.
larger amount passes from pulmonary trunk.
Through ductus arteriosus to aorta distal to its branches. to
descending aorta.
=It supplies lower half of the body.
=Then the blood passes from umbilical arteries to placenta.
2*The small portion of blood

138. PROCESS
OF
DEVELOPMENT
FETAL CIRCULATION CHANGES AT BIRTH

139. 1]=Ligature of umbilical cord.
2]=Exposure to cold.
*CAUSES OF THESE CHANGES:-

140. The two umbilical arteries:-
=It will give the following derivatives:-
(1)-The proximal portion:-remains patent superior vesical artery.
(2)-The distal portion:- will form lateral umbilical ligaments.
The umbilical veinligamentum teres of liver.
Ductus venosus:ligamentum venosum of liver.
Foramen ovale:
=occluded due to:-
1]-increased pressure of Lt. atrium.
2]-decreased pressure of Rt. atrium due to decreased blood from I.V.C.
=It will give the following derivatives:-
*Fossa ovalis :-from septum premium.
*Annulus fossa ovalis:- from septum secondum.
1]=Ligature of umbilical cord

141. 1-respiration is stimulated.
2-lungs become functioning.
3-decrease in resistence of lungs.
4-blood shifted from pulmonary trunk to lungs for
oxygenation.
5-It returns to Lt. atrium through pulmonary veins
leads to increase Lt. atrium pressure inside.
6-closure of ductus arteriosus will give:-
ligamentum arteriosum.
2]=Exposure to cold:-

142. ‫هلل‬ ‫الحمد‬