Anatomy of the heart.pdf. Histological .

This ppt I'm presentation gives the anatomy of the heart both embryologically and gross aspects

1. ANATOMY OF THE
HEART
Mrs. Sichela

2. INTRODUCTION
•The heart is a conical hollow muscular organ situated in the middle
mediastinum. It pumps blood to various parts of the body
•Greek-cardia
•Latin-coronary
•Four chamber muscular organ
•Comparable to the size of a closed fist
•Located in the mediastinum
•Behind sternum
•Between 2
nd
and 6
th
ribs
•Between T5-T8
•Apex
•Located at the 5
th
intercostal space

3. FUNCTIONS OF THE HEART
•Pumps oxygenated and
nutrient-rich blood to the
body through blood vessels
•Pumps deoxygenated
blood, containing wastes, to
the lungs, where gas
exchange to the outside
environment occurs

4. RELATIONS OF THE
HEART
•Superiorly –the aorta, superior vena
cava, pulmonary artery and
pulmonary vein.
•Inferiorly –the diaphragm
•Anteriorly –the ribs and intercostal
muscles.
•Posteriorly –the esophagus,
trachea, left and right bronchus,
descending aorta, inferior vena
cava and thoracic vertebrae
•Laterally –the lungs
Posterior relations

6. EXTERNAL FEATURES
The heart has
An apex directed to the left
A base (posterior surface)
Anterior (sternocostalsurface)
Inferior (diaphragmatic surface)
Lateral (pulmonary surface)
The surfaces are demarcated by upper, inferior, right and left
borders.

11. MARGINS AND BORDERS
•Some general descriptions of cardiac orientation refer to right, left, inferior
(acute), and obtuse margins:
•The right and left margins are the same as the right and left pulmonary
surfaces of the heart;
•The inferior margin is defined as the sharp edge between the anterior and
diaphragmatic surfaces of the heart
•It is formed mostly by the right ventricle and a small portion of the left
ventricle near the apex;
•The obtuse margin separates the anterior and left pulmonary surfaces -it is
formed mostly by the left ventricle and superiorly by a small portion of the left
auricle.

13. COVERINGS OF THE HEART:
PERICARDIUM
•The heart is enclosed in a double-walled sac
called the pericardium
•It consists of two main parts:
1.The fibrous pericardium
2.The serous pericardium
The fibrous pericardium
•is composed of tough, inelastic, dense
irregular connective tissue.
•The functions of fibrous pericardium is to
1.Prevent overstretching of the heart
2.Protection of heart
3.Anchors the heart in the mediastinum

14. Serous pericardium
•is a thinner membrane that forms a
double layer around the heart
•The outer parietal layer: it is fused to
the fibrous pericardium.
•The inner visceral layer is also called
the epicardium helps the layers of the
heart wall to adheres tightly to the
surface of the heart.
•Pericardial cavity: between parietal
and visceral layer
•Filled with 10-15mL of pericardial
fluid
•Decreases friction

15. BLOOD SUPPLY
The fibrous and parietal pericardia are supplied by
Internal thoracic , musculophrenicarteries, descending thoracic aorta
Veins drain into corresponding veins.
NERVE SUPPLY
Phrenic nerve

16. SULCI OF THE HEART
•Internal partitions divide the heart into four chambers (i.e. two atria and two
ventricles) and produce surface or external grooves referred to as sulci.
The coronary sulcus
•circles the heart, separating the atria from the ventricles
•Contains the right coronary artery, the small cardiac vein, the coronary
sinus, and the circumflex branch of the left coronary artery.
The anterior and posterior interventricular sulci
•separate the two ventricles

17. •The anterior interventricular sulcus
•is on the anterior surface of the heart
•contains the anterior interventricular arteryand the great cardiac
vein
•The posterior interventricular sulcus
•is on the diaphragmatic surface of the heart
•contains the posterior interventricular artery and the middle
cardiac vein.
•These sulci are continuous inferiorly, just to the right of the apex of
the heart.

19. AURICLE
•Anterior surface of each atrium is a
wrinkled pouch-like structure called
an auricle.
•Each auricle slightly increases the
capacity of an atrium so that it can
hold a greater volume of blood.

20. WALLS OF THE HEART
Epicardium –outer layer
Epicardium = serous pericardium
Myocardium –thick, contractile
layer composed of cardiac
muscle cells
Intercalated disks contain many
gap junctions
Allow cardiac muscle cells to
function as a single unit 
syncytium
Endocaridium–interior of
cardiac wall
Endothelial tissue
Covers projections of myocardial
tissue called trabeculae

22. CHAMBERS OF THE HEART
•Atria–two superior chambers
•“Receiving chambers”
•Blood from veins enters atria
•Ventricles–two inferior chambers
•“pumping chambers”
•Thick muscular walls to increase force of pumping action
•Left > right
•Separated by interventricular septum

23. CHAMBERS OF THE HEART

24. EMBRYOLOGY OF HEART
•The heart is the first organ to start functioning in the human embryo.
•During the third week of intrauterine life, the angiogeniccells in the
cardiogenic area at the cranial end of the embryonic disc form right
and left endothelial cardiac tubes.
•Around twenty second day of development, a single straight cardiac
tube is formed by their fusion.
•Thus, the cardiac tube is mesodermal in origin.

26. SUBDIVISIONS OF CARDIAC TUBE
•The cardiac tube is divisible into five
chambers in craniocaudalorder as follows:
•Truncus arteriosus
•Bulbuscordis
•Common ventricle
•Common atrium
•Sinus venosus.
•The truncus arteriosus is the cranial or arterial
end of cardiac tube.
•The sinus venosusis the caudal or venous end
of and has a left and right cardiac tube.

27. FURTHER DEVELOPMENT OF HEART TUBE
•The folding of the cardiac tube changes the tubular heart to a U-shaped bulbo-
ventricular loop.
•The sinus venosusmoves upwards along with atrial chamber to lie behind and
above the ventricle.
•The shape of the heart now changes to S-configuration
•By the end of 25 to 27 days the embryonic heart begins rhythmic beating.

31. SEPTATION OF EMBRYONIC HEART
•Occurs between week 4-8
•The dorsal and ventral walls of the atrioventricular canal develop
endocardial cushions, which fuse with each other to form the septum.
•This divides atrioventricular canal into right and left
•A thin septum primum, grows toward the fusing endocardial cushions
from the roof of the primordial atrium
•A large opening, the foramen primum(ostium Primum), is located
between its free edge and the endocardial cushions which serves as
a shunt for oxygenated blood to move from right to let atria
•Note: Endocardial cushions assist in formation of the atrial and
ventricular (membranous portion) septa, the atrioventricular canals
and valves, and the aortic and pulmonary channels

32. •Before the fusion of septum primumwith endocardial cushions (and
consequent closure of the foramen primum), the upper part of the
septum primumbreaks down to form foramen secundumor ostium
secundum.
•A thick septum secundumgrows from the right atria adjacent to
septum primumdruingweeks 5 and 6 and overlaps foramen
secundum
•Lower margin of septum secundumis free
•The oblique gap between the lower margin of septum secundumand
the upper margin of septum primumis called foramen ovale.
•The septum primumacts as a flap valve since the pressure is greater in
the right atrium than in the left in fetal life.

33. CLOSURE OF FORAMEN OVALE
•The foramen ovalecloses after birth. This is accomplished as follows.
•The rise in the left atrial pressure soon after establishment of pulmonary
circulation keeps the septum primumpressed against the septum secundum
until they fuse.
•The septum primumbecomes the floor of fossa ovalisand the lower margin
of the septum secundumforms the limbus fossa ovalis.
•The functional closure of the foramen ovaleoccurs immediately after birth
while the anatomical closure occurs 6 to 12 months after birth.
•In 15 to 20 percent of persons probe patency remains (this is symptom free).

36. CHANGES IN SINUS VENOSUS
•At first, communication between the sinus and the atrium is wide.
•Soon, however, the entrance of the sinus shifts to the right
•This shift is caused primarily by left-to-right shunts of blood, which occur in the
venous system during the 4
th
and 5
th
weeks of development
•This causes the right sinus horn to enlarge greatly.
•Theright horn is incorporated into the right atrium to form the smooth-walled
part of the right atrium
•The left horn becomes the coronary sinus

37. PARTITIONING OF THE PRIMORDIAL
VENTRICLE
•Left and right ventricles are partitioned by an interventricular septum that
grows superiorly from the floor of the ventricles.
•Until the seventh week, there is a crescent-shaped Interventricular (IV)
foramen between the free edge of the IV septum and the fused
endocardial cushions.
•The IV foramen permits communication between the right and left ventricles
•The IV foramen usually closes by the end of the seventh week
•The membranous part of the IV septum is derived from an extension of tissue
from the right side of the endocardial cushion to the muscular part of the IV
septum

40. CLINICAL CORRELATES: HEART DEFECTS
•Atrial septal defect (ASD) is the congenital anomaly, which becomes manifest in
adult life. There are three types of ASD resulting in left to right shunt.
•Ostium secundumdefect (persistence of foramemsecundum) is the most common.
Results from excessive resorption in the septum primumor of failure of development
of septum secundum.
•Ostium primumdefect ( persistence of foramen primum) is due either to the failure of
the septum primumto reach the endocardial cushions or due to defect in the
endocardial cushions.
•Patent foramen ovaleis due to failure of the septum primumand septum secundum
to fuse after birth. This is extremely rare.
•Cortrilocularebiventriculare: complete absence of atrial septum. Very serious
abnormally

41. •Transpositonof great arteries:
the two main arteries leaving
the heart are reversed.
•The pulmonary artery is exits
the left ventricle and the aorta
exits the right ventricle

42. •Dextrocardia: the heart rotates to the
right so that its apex is located in the
right fifth intercostal space.
•The ventricular septal defect(VSD) is a commonly
occurring congenital anomaly.

43. •Tetralogy of Fallot(TOF) is a
combination of four defects, which
includes
•Ventricular Septal Defect,
•Over-riding of aorta (ascending
aorta-having connection to both
ventricles)
•Pulmonary stenosis (and narrowing of
pulmonary trunk, and
•Right ventricular hypertrophy.
•The aorta carries mixed blood, which
results in cyanosis

46. RIGHT ATRIUM
In the anatomical position, the right
border of the heart is formed by the
right atrium.
Blood returning to the right atrium
enters through one of three vessels.
These are:
the superior and inferior venae
cavae, which together deliver
blood to the heart from the body;
and
the coronary sinus, which returns
blood from the walls of the heart
itself.

47. RIGHT ATRIUM
•The interior of the right atrium
is divided into two continuous
spaces.
•Externally, this separation is
indicated by a shallow,
vertical groove (the sulcus
terminaliscordis),

48. RIGHT ATRIUM
•Internally, this division is
indicated by the crista
terminalis.
•The space posterior to the crista
is the sinus of venae cavaeand
is derived embryologicallyfrom
the right horn of the sinus
venosus.
•This component of the right
atrium has smooth, thin walls,
and both venae cavaeempty
into this space.

49. RIGHT ATRIUM
•Its walls are covered by ridges called
the musculipectinati(pectinate
muscles)
•In the right atrium is the opening of
coronary sinus
•The fossa ovalis(oval fossa), with its
prominent margin, the limbus fossa
ovalis(border of oval fossa).
•Numerous small openings-the
openings of the smallest cardiac
veins (the foramina of the venae
cordisminimae

50. RIGHT VENTRICLE
•In the anatomical position, the right
ventricle forms most of the anterior
surface of the heart and a portion
of the diaphragmatic surface
•The outflow tract of the right
ventricle, which leads to the
pulmonary trunk, is the conus
arteriosus (infundibulum) -bulbus
cordis.
•It has numerous muscular, irregular
structures called trabeculae
carneae
•A few trabeculae carneae
(papillary muscles) have only one
end attached to the ventricular
surface and the other serves as
attachment for chordae tendinae
•Three papillary muscles namely
anterior (Iargest), septal and
posterior

51. SEPTOMARGINALTRABECULA
•Also called moderator band
•Forms a bridge between the
lower portion of the
interventricular septum and the
base of the anterior papillary
muscle.
•The septomarginaltrabeculum
carries a portion of the cardiac
conduction system, right bundle
of the atrioventricular bundle, to
the anterior wall of the right
ventricle.

53. TRICUSPID VALVE
•The right atrioventricular orifice is closed during ventricular contraction
by the tricuspid valve (right atrioventricular valve), so named because
it usually consists of three cusps or leaflets
•the anterior, septal, and posterior cusps,

54. PULMONARY VALVE
At the apex of the infundibulum, the
opening into the pulmonary trunk is
closed by the pulmonary valve
(which consists of three semilunar
valves)

55. LEFT ATRIUM
•The left atrium forms most of the base
or posterior surface of the heart.
The posterior half, or inflow portion,
receives the four pulmonary veins.
The anterior half is continuous with
the left auricle. It contains musculi
pectinatiand derives from the
embryonic primitive atrium.
The thin area or depression in the
septum is the valve of the foramen
ovaleand is opposite the floor of the
fossa ovalisin the right atrium.

57. LEFT VENTRICLE
•The left ventricle lies anterior to the left atrium. It contributes
to the anterior, diaphragmatic, and left pulmonary surfaces
of the heart, and forms the apex.
•The outflow tract (the aortic vestibule) is posterior to the
infundibulum of the right ventricle, has smooth walls, and is
derived from the embryonic bulbuscordis
•Trabeculae carneaein the left ventricle are fine and
delicate in contrast to those in the right ventricle.
•Papillary muscles, together with chordae tendineae, are
also observed.
•Two papillary muscles, the anteriorand posterior.

59. MITRAL VALVE
•The left atrioventricular orifice opens into the posterior right side
of the superior part of the left ventricle.
•It is closed during ventricular contraction by the mitral valve
(left atrioventricular valve), which is also referred to as the
bicuspid valve because it has two cusps, the anterior and
posterior cusps

60. AORTIC VALVE
The opening from the left ventricle into the aorta is closed by the aortic valve. This
valve is similar in structure to the pulmonary valve. It consists of three semilunar cusps
with the free edge of each projecting upward into the lumen of the ascending
aorta

62. THE HEART: CONDUCTION
SYSTEM
•The heart pumps blood through the body
•This is accomplished by contraction and relaxation of the cardiac
muscle tissue in the myocardium layer.
•Intercalated discs allow impulses to travel rapidly between adjacent
cells so they function as one rather than individual cells

63. COMPONENTS OF THE
CONDUCTION SYSTEM
•Sinoatrial Node(Part I):
•located at the junction of
the superior vena cava
and the right atrium
•called the pacemakerof
the heart
•impulses move through
atria causing the two atria
to contract.
•at the same time, impulses
reach the second part of
the conduction system

64. COMPONENTS OF THE CONDUCTION
SYSTEM CONTINUED ….
•Atrioventricular Node(Part II):
•locatednear the opening of the
coronary sinus
•cells in the AV node conduct
impulses more slowly, so there is
a delay as impulses travel
through the node
•this allows time for atria to finish
contraction before ventricles
begin contracting

65. ATRIOVENTRICULAR BUNDLE
•A.K.A. “Bundle of His”
•From the AV node, impulses travel
through to the right and left bundle
branches
•These branches extend to the right
and left sides of the septum and
bottom of the heart.
•These branch to form the Purkinje
fibersthat transmit the impulses to the
myocardium (muscle tissue)
•The bundle of His, bundle branches
and Purkinje fibers transmit quickly
and cause both ventricles to
contract at the same time

66. ATRIOVENTRICULAR BUNDLE
CONTINUED….
•As the ventricles contract, blood is forced out through the semilunar
valves into the pulmonary trunk and the aorta.
•After the ventricles complete their contraction phase, they relax and
the SA node initiates another impulse to start another cardiac cycle.

68. BLOOD SUPPLY TO THE HEART
•Arterial Supply
•The first two branches of the aorta, called the right and left coronary arteries,
supply blood to the tissues of the heart.
•The left coronary artery runs toward the left side of the heart and then divides
into two major branches:
•The anterior interventricular artery follows the anterior interventricular sulcus
and supplies blood to the interventricular septum andanterior walls of both
ventricles.
•The circumflex artery supplies the left atrium and the posterior walls of the left
ventricle.

69. •The right coronary artery courses to the right side of the heart, and follows the
coronaysulcus. The branches include:
•Atrial branch (supplying the anterior part of the right atrium and the SA node
through a nodal branch-sinu-atrial branch
•The right marginal arterywhich travels along the inferior margin of the heart,
supplying both the ventricles on its way.
•The posterior interventricular artery supplies blood to the posterior ventricular
walls and merges (anastomoses) with the anterior interventricular artery.

72. CORONARY VEINS
•The venous blood is collected by the cardiac veins.
•These veins join to form an enlarged vessel called the coronary sinus, which empties
the blood into the right atrium.
The principal tributaries carrying blood into the coronary sinus are the following:
•Great cardiac vein in the anterior interventricular sulcus, which drains the areas of
the heart supplied by the left coronary artery (left and right ventricles and left
atrium)
•Middle cardiac vein in the posterior interventricular sulcus, which drains the areas
supplied by the posterior interventricular branch of the right coronary artery (left and
right ventricles)
•Small cardiac vein in the coronary sulcus, which drains the right atrium and right
ventricle
•Anterior cardiac veins, which drain the right ventricle and open directly into the right
atrium

73. OTHER CARDIAC VEINS
•Two additional groups of cardiac veins are also involved in the venous
drainage of the heart:
•The anterior veins of right ventricle (anterior cardiac veins): They drain the
anterior portion of the right ventricle. Drain directly into the right atrium
•A group of smallest cardiac veins (venae cordisminimaeor veins of
Thebesius) Drain directly into the cardiac chambers, they are numerous in
the right atrium and right ventricle, are occasionally associated with the left
atrium, and are rarely associated with the left ventricle.

74. NERVE SUPPLY TO THE HEART
•The autonomic division of the PNS is
directly responsible for regulating:
•heart rate;
•force of each contraction;
•cardiac output.
•Branches from both the
parasympathetic and sympathetic
systems contribute to the formation of
the cardiac plexus
•Branches from the cardiac plexus affect
nodal tissue and other components of
the conduction system, coronary blood
vessels, and atrial and ventricular
musculature.

75. Parasympathetic innervation
•Stimulation of the parasympathetic
system:
•decreases heart rate;
•reduces force of contraction;
•constricts the coronary arteries
Sympathetic innervation
•Stimulation of the sympathetic
system:
•increases heart rate;
•increases the force of contraction.
•Dilates the coronary arteries

76. GREAT VESSELS
•Large blood vessels which arise from the heart and their immediate
branches.
•carry blood into and out of various chambers of the heart
•Ascending aorta
•Pulmonary trunk
•Superior vena cava
•Inferior vena cava
•Pulmonary veins
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