2. HEART
• Greek, Heart = cardia = adj. cardia
• Latin, Heart = cor = adj. coronary.
- It is hollow fibromuscular organ
situated in middle mediastinum.
- covered by pericardium.
• External features:-
Four chamber:- right and left atria,
right and left ventricles.
Groove:- atrioventricular groove(coronary sulcus),
interatrial groove , and
interventricular groove.
3. Contd…..
• Measurement:-
apex to base:- 12 cm
antero-posterior diameter:- 6 cm
transverse diameter:- 9 cm
• Weight :- adult male:- 300 gm
adult female:- 250 gm
• Presenting parts:-
- apex,
- base,
- 4 border ( upper, right, left, inferior)
- 3 surface - anterior or sternocostal,
- inferior or diaphragmatic ,
- left surface.
5. EARLIEST DEVELOPMENT OF HEART
A mass of mesoderm forming a curve which reaches well beyond
the neural plate and the notochord, called cardiogenic area, near
the head end will give rise to the heart.
Mesenchymal cells in the cardiogenic area form two angioblastic
cords.
The sagittal section below illustrates the three germ layers,
prochordal plate and the cardiogenic area.
Prochordal plate
Cardiogenic area
7. TUBE FORMATION BEGINS
ROSTRALLY
• Angioblastic cords
become canalized to
form two endothelial
heart tubes.
• These endothelial heart
tubes fuse to form a
single endothelial heart
tube.
8. The single endothelial heart tube thus formed shows a
series of dilatations.
These are :-
1 Bulbus cordis
2. Ventricle
3. Atrium
4. Sinus venosus
12. 1-Vitelline Vein 2- UmbilicalVein
3-Common Cardinal Veins
CIRCULATION THROUGH THE PRIMITIVE
HEART
13. Contd….
Bulbus cordis:-
- the cranial most part of the tubular
heart , subsequently divided into 3
parts:-
1. proximal part:-
- later it form trabeculated part of
right ventricle.
2. conus cordis:-
- later it form outflow tract of both
right & left ventricle.
3. Truncus arterious:-
- later it form ascending aorta &
pulmonary trunk.
14. Contd…..
Primitive ventricle:-
- along with the conus cordis will form right &left
ventricle.
- junction of primitive ventricle with bulbus
cordis , is called bulboventricular sulcus.
Primitive atrium:-
- connected with primitive ventricle through
atrioventricular canal.
- Later it will form right &left atria.
15. Contd….
Sinus venous:-
- lies at the venous end of heart tube.
- it has right & left horn.
- each horn receives blood from following 3
veins:-
a. Vitelline vein from yolk sac.
b. Umbilical vein from placenta.
c. Common cardinal vein from body wall.
16.
17. FORMATION OF ATRIA
It involves following process:-
1. Formation of septum spurium
2. Septation of atrio- ventricular canal
1. Formation of septum spurium:-
18. Contd….
2. Septation of atrio- ventricular
canal:-
Atrio-ventricular canal divides
into right & left halves as
follows:-
- Two thickening, the atrio-
ventricular cushion appear on
its dorsal & ventral walls.
- They grow towards each other
& fuse . The fused cushions
form the septum intermedium.
20. Development of Right Atrium
• Right half of primitive atrium:-
- form the main part of musculi pectinati & right auricle.
• Enlarge right horn of sinus venosus:-
- incorporated into right atrium forms the posterior smooth part
(sinus venarum).
- superior venacava & inferior venacava open in this part.
• Right half of atrio-ventricular canal:-
- also called tricuspid valve , which allow flow of blood from
right atrium to right ventricle.
- right A-V canal is guarded by tricuspid valve.
• Interatrial septum:-
- separates right atrium from the left atrium.
22. Fate of right and left venous valve
Rt venous valve:-
crista terminalis,
valve of IVC& coronary
sinus
23. Foramen Ovale
• The oval foramen closes at birth
• Anatomical closure is due to adhesion of the
septum primum (the valve of the foramen ovale)
to the left margin of the septum secundum..
• The septum primum forms the floor of the fossa
ovalis.
• The inferior edge of the septum secundum
forms a rounded fold, the limbus fossae ovalis
(anulus ovalis).
24.
25. Development of Left Atrium
• Left half of primitive atrium
- forms the main parts of musculi pectinati & left auricle.
• Absorbed proximal part of pulmonary veins
- forms the smooth part.
- four pulmonary veins bringing oxygenated blood from lung
and drain into left atrium.
• Left half of atrio-ventricular canal
- also called mitral valve (bicuspid valve), which allow flow of
blood from left atrium to left ventricle.
- left A-V canal is guarded by mitral valve which are formed by
proliferation of connective tissue under endocardium of
left A-V canal.
27. DEVELOPMENT OF VENTRICLES
• Fate of bulbus cordis:-
Bulbus cordis is divisible into
3 parts:-
1. Truncus arteriosus.
2. Conus cordis.
3. proximal parts of
bulbus cordis.
28. Contd….
• Truncus Arterious:-
A spiral septum appears within truncus arterious and
subdivided it into ascending aorta & pulmonary trunk.
it is formed by the fusion of right superior & left
inferior truncus swelling or cushion.
29. Formation of interventricular septum
• The bulboventricular cavity
formed after the conus cordis
& proximal part of bulbus
cordis have merged into
primitive ventricle has to be
subdivided into right & left
halves of ventricle in such
way that:-
a. Each halves communicate
with the corresponding
atrium
b. Right ventricles open into
pulmonary trunk & left
ventricle into the aorta.
30.
31. Valves of the Heart
Function :-The valves of the heart maintain unidirectional flow
of blood & prevent regurgitation in the opposite direction.
• There are 2 pair of valves in the heart:-
1. A pair of atrioventricular valve
- mitral(bicuspid) & tricuspid valves are proliferation of
connective tissue under endocardium of the right & left
atrioventricular canals.
2. A pair of semilunar valve
- aortic & pulmonary valves derived from endocardial cushion
that are formed at the junction of the truncus arteriosus &
conus cordis.
33. CONGENTIAL MALFORMATIONS
• ACARDIA
– Absence of heart
• Only occurs in conjoined monozygotic twins
• 1:35,000
• ECTOPIC CORDIS
– Heart is located through a sternal fissure into:
• Into the neck
• Down through a diaphragmatic hernia into a
exomphalocoele
• Protruding outside chest
–Dextra thoracic ectopia
»Limited life expectancy
35. CONGENITAL MALFORMATIONS
• DEXTRACARDIA
– Heart is located in right hemithorax
– Most cases associated with situs inversus
• Heart, great vessels, other thoracic & abdominal
organs may present a mirror image of the norm.
• 1:10,000
– Known to occur with other anomolies
• Duodenal atresia
• Agenesis of spleen
• Spina bifida
– Isolated cases rare (1:900,000)
36. NORMAL : Loop to the RIGHT: LEVOCARDIA
ABNORMAL: Loop to the LEFT: DEXTROCARDIA
37. Defective formation of septa
• Interatrial septal defect:-
3 types:- A. septum primum defect.
B. septum secundum defect
C. patent foramen ovale.
• Interventricular septal defect.
40. • Taussing- Bing syndrome:-
Aorta arises from right ventricle; & pulmonary
trunk overrides both the right &left ventricle, there
being an interventricular septal defect.
• Eisenmergers complex:-
is a combination of pulmonary hypertension due to
- hypoplasia of pulmonary complex
- dilatation of pulmonary trunk,
- hypertrophy of right ventricle.
when associated ASD,VSD,& PDA the condition is
termed Eisenmergers complex.
44. Conducting system of Heart
Formation
1. SA node :-
it is formed from pacemaker which occupies
following position.
- initially lies in the caudal part of left tube .
- after fusion of two tube, it lies in the sinus venosus,
- when the sinus venosus incorporated into right atrium, it
comes to lie near the opening of SVC.
2. AV node & bundle of His:-
are formed from 2 source :-
I. left wall of sinus venosus
II. Atrioventricular canal.
- after incorporation of sinus venosus into the right
atrium, the final position taken by these cells is at the
base of interatrial septum.
45. THE DEFINITIVE RIGHT ATRIUM
**NOTE: In 25% of normal population, the
foramen ovale remains ‘probe patent’.
