The heart is a hollow muscular organ with four chambers (two atria and two ventricles) that pumps blood through the circulatory system. It is enclosed by the pericardium, which consists of a fibrous outer layer and a serous inner layer, and has its own blood supply from the coronary arteries. Heart valves ensure unidirectional blood flow, preventing backflow during contractions.

1. ANATOMY OF THE HEART

2. The Pericardium
• The pericardium is a
fibroserous sac that
encloses the heart
and the roots of the
great vessels.
• The pericardium lies
within the middle
mediastinum.

3. The Pericardium

4. The Pericardium
• Its function is to
restrict excessive
movements of the
heart as a whole and
to serve as a
lubricated container
in which the different
parts of the heart can
contract.

5. The Pericardium
1. A superficial fibrous
pericardium
2. A deep two-layer
serous pericardium
a. The parietal layer lines
the internal surface of
the fibrous pericardium
b. The visceral layer or
epicardium lines the
surface of the heart
• They are separated by
the fluid-filled
pericardial cavity

6. The Pericardium

7. The Pericardium
Blood Supply
• The pericardium blood
supply is from the
pericardiacophrenic
branches of the
internal thoracic
arteries.
Nerve Supply
• The fibrous pericardium
and the parietal layer
of the serous
pericardium - phrenic
nerves.
• The visceral layer of the
serous pericardium
-branches of the
sympathetic trunks
and the vagus nerves.

8. The Heart
• The heart is a hollow
muscular organ that is
somewhat pyramid
shaped and lies within
the pericardium in the
mediastinum .
• It is connected at its
base to the great blood
vessels but otherwise
lies free within the
pericardium.

9. The Heart
It pumps blood
received from the
veins into the
arteries, thereby
maintaining the flow
of blood through the
entire circulatory
system.

10. The Heart
• The heart is
surrounded by
membrane called
Pericardium.

11. Heart Wall
• Epicardium – visceral layer of the serous
pericardium
• Myocardium – cardiac muscle layer
forming the bulk of the heart
• Fibrous skeleton of the heart –
crisscrossing, interlacing layer of
connective tissue
• Endocardium – endothelial layer of the
inner myocardial surface

12. Heart Wall
• Endocardium
– deepest layer of the
heart
– smooth lining to reduce
friction of bloodflow
• Myocardium
– middle layer of the
heart
– location of muscle
fibers responsible for
pumping
• Pericardium
– outer protective layer
– composed of :
– visceral pericardium
– paricardial cavity
– parietal pericardium

13. Heart Wall

14. Heart Surfaces
• The Anterior
(sternocostal)
surface is formed
mainly by the right
atrium and the right
ventricle, which are
separated from each
other by the vertical
atrioventricular
groove.

15. The Heart Surfaces
• The diaphragmatic surface of the heart
is formed mainly by the right and left
ventricles separated by the posterior
interventricular groove.
• The inferior surface of the right atrium,
into which the inferior vena cava opens,
also forms part of this surface.

16. Heart Surfaces
• The base of the
heart, or the
posterior surface,
is formed mainly
by the left atrium,
into which open
the four
pulmonary veins.

17. Heart Surfaces
• The apex of the heart,
formed by the left
ventricle, is directed
downward, forward,
and to the left.
• It lies at the level of
the fifth left
intercostal space, 3.5
in. (9 cm) from the
midline.

18. Borders of the Heart
• The right border is formed
by the right atrium
• The Left border, by the
left auricle; and below, by
the left ventricle.
• The lower border is
formed mainly by the
right ventricle but also by
the right atrium.

19. The Heart Chambers
• Four chambers
• Two atria (Right
and Left)
• Two ventricles
(Right and Left)

20. The Heart Chambers
• Atria
– Features
➢ small, thin-walled
chambers
– Functions
➢ receiving chambers
for blood returning
to the heart from
the circulation
➢ push the blood into
the adjacent
ventricles.

21. The Heart Chambers
• Atria
– Receive blood
from
➢ Right side
❖ Superior and
Inferior Vena
Cava
❖ Coronary Sinus
(draining the
myocardium)
➢ Left side
❖ Pulmonary Veins

22. The Heart Chambers
• Ventricles
– Features
➢ make up most of
the mass of the
heart
➢ the walls of the
left ventricle are
3X thicker than
those of the
right

23. The Heart Chambers
• Ventricles
– Functions
➢discharging
chambers of the
heart
➢propel blood to
Pulmonary Trunk
(right ventricle),
Aorta (left
ventricle)

24. The Right Atrium
• Receives deoxygenated
blood from the inferior
vena cava below and
from the superior vena
cava above.
• Receives the coronary
sinus in its lower part.
• The upper end of the
atrium projects to the
left of the superior vena
cava as the right
auricle.

25. The Right Atrium
• The sulcus terminalis is
a vertical groove on the
outer surface of the
atrium. This groove
corresponds internally to
the crista terminalis .
• Above the coronary sinus
the interatrial septum
forms the posterior wall.
The depression in the
septum the fossa ovalis
are presents the site of
the foramen ovale.

27. The Right Ventricle
• Receives blood from
the right atrium
through the tricuspid
valve .
• The edges of the valve
cusps are attached to
chordae tendineae
which are, in turn,
attached below to
papillary muscles.

28. The Right Ventricle
• The wall of the right
ventricle is thicker than
that of the atria but not
as thick as that of the
left ventricle.
• The wall contains a mass
of muscular bundles
known as trabeculae
carneae.
• The infundibulum is the
smooth walled outflow
tract of the right
ventricle.

29. The Right Ventricle
• The pulmonary valve is
situated at the top of
the infundibulum.
• It is composed of three
semilunar cusps.
• Blood flows through the
valve and into the
pulmonary arteries via
the pulmonary trunk to
be oxygenated in the
lungs.

31. The Left Atrium
• Receives oxygenated
blood from four
pulmonary veins
which drain
posteriorly.
• The cavity is smooth
walled except for the
atrial appendage.
• On the septal surface
a depression marks
the fossa ovalis.

32. The Left Atrium
• The mitral (bicuspid)
valve guards the
passage of blood from
the left atrium to the
left ventricle.

33. The Left Ventricle
• The wall of the left
ventricle is thicker than
the right ventricle but the
structure is similar.
• The thick wall is necessary
to pump oxygenated blood
at high pressure through
the systemic circulation.
• Trabeculae carneae
project from the wall with
papillary muscles attached
to the mitral valve cusp
edges by way of chordae
tendineae.

34. The Left Ventricle
• The vestibule is a
smooth walled part of
the left ventricle
which is located
below the aortic valve
.

36. The Heart Valves
• Heart valves ensure
unidirectional
blood flow through
the heart
• Two major types
–Atrioventricular
valves
–Semilunar valves

38. Atrioventricular (AV) Valves
• Atrioventricular (AV)
valves lie between the
atria and the ventricles
– R-AV valve =
tricuspid valve
– L-AV valve =
bicuspid or mitral
valve
• AV valves prevent
backflow of blood into
the atria when
ventricles contract

39. Atrioventricular Valve

40. Semilunar Heart Valves
• Semilunar valves
prevent backflow of
blood into the
ventricles
• Aortic semilunar valve
lies between the left
ventricle and the aorta
• Pulmonary semilunar
valve lies between the
right ventricle and
pulmonary trunk

41. Semilunar Valve

42. The Heart Valves
• Right AV (Tricuspid)
– separates the right
atrium from the right
ventricle. Prevents
backflow into atrium.
• Left AV (Bicuspid)
– separates the left
atrium from the left
ventricle. Prevents
backflow into atrium.
• Pulmonary valve
– separates the right
ventricle from the
pulmonary arteries.
Prevents backflow after
ventricular contraction.
• Aortic valve
– separates the left
ventricle from the
aorta. Prevents
backflow after
ventricular contraction .
Atrioventricular valves Semilunar valve

43. The Heart Valves
Pulmonary
semilunar valve
Aortic
semilunar valve
Left AV
(bicuspid)
valve
Right AV
(tricuspid)
valve
Chordai
tendineae
Papillary
muscle

44. The Heart Valves

45. Arterial Supply of the Heart
• The arterial supply of
the heart is provided
by the right and left
coronary arteries,
which arise from the
ascending aorta
immediately above
the aortic valve.

46. Coronary Arteries
The origins of the coronary
arteries are as follows:
• The left coronary
artery arises from the
aortic sinus immediately
above the left posterior
cusp of the aortic valve .
• The right coronary
artery arises from the
aortic sinus immediately
above the anterior cusp
of the aortic valve.

47. Right coronary artery
Branches
– Right marginal arteries
(acute marginal artery)
– Posterior
interventricular artery.
(in post. IV sulcus)
– Sinoatrial nodal artery.
– Atrioventricular nodal
artery.

48. Left coronary artery
Branches
– Left anterior
descending (LAD) or
anterior interventricular
artery. (lies in anterior
IV sulcus)
• Septal branches.
• Diagonal branches
– Left marginal artery.
(Obtuse marginal
artery)
– Left circumflex artery.

49. Coronary Arteries

50. Venous Drainage of the Heart
• Most blood from the
heart wall drains into
the right atrium through
the coronary
sinus ,which lies in the
posterior part of the
atrioventricular groove .
• It is a continuation of
the great cardiac vein.
• It opens into the right
atrium to the left of the
inferior vena cava

51. Venous Drainage of the Heart

52. Nerve Supply of the Heart
• The heart is innervated by sympathetic and
parasympathetic fibers of the autonomic
nervous system via the cardiac plexuses
situated below the arch of the aorta.
• The sympathetic supply arises from the
cervical and upper thoracic portions of the
sympathetic trunks, and the
parasympathetic supply comes from the
vagus nerves.

53. THANK YOU

57. External Heart: Anterior View

58. External Heart: Posterior View

59. Gross Anatomy of Heart: Frontal
Section