Download Pericardium & Heart

Heart enclosed within
the pericardial sac is
located in the middle
mediastinum
Mediastinum
The cavity of thorax is divided into:
• A median partition, the
mediastinum
• Laterally placed pleurae & lungs
Mediastinum is a thick mobile
partition, formed by the structures
occupying the central part of the
thoracic cavity, between the lungs
It extends:
• Superiorly to the thoracic inlet &
the root of neck
• Inferiorly to the diaphragm
• Anteriorly to the sternum
• Posteriorly to the twelve thoracic
vertebrae
Mediastinum: Divisions
Divided, by an imaginary
plane passing from the
sternal angle anteriorly to
the lower border of the body
of the 4th thoracic vertebra
posteriorly, into:
• Superior mediastinum
• Inferior mediastinum
The inferior mediastinum is
further divided into:
• Anterior
• Middle
• Posterior
Pericardium
Double layered fibroserous
sac that encloses the heart &
the roots of the great vessels
Located in the middle
mediastinum
 Posterior to the body of
sternum and 2nd-6th
costal cartilages
 Anterior to T5-T8
vertebrae
 1-1.5 cm to the right of the
sternum
 5-7.5 cm to the left of
median plane at the level
of 5th intercostal space
Pericardium cont’d
The strong outer layer,
the fibrous pericardium
is composed of tough
fibrous tissue
The inner transparent
membrane, the serous
pericardium, has two
layers:
• Parietal
• Visceral
Fibrous Pericardium
Tough conical outer
fibrous sac, protects heart
against sudden overfilling
Superiorly:
 Pierced by aorta,
pulmonary trunk, and
superior vena cava
 Becomes fused with the
tunica adventitia of
these vessels
Below: rests on and is
fused with the central
tendon of the diaphragm
Fibrous Pericardium cont’d
Anteriorly attached to the
posterior surface of
sternum by
condensations of
connective tissue called
the sternopericardial
ligaments
Posteriorly:
 Pierced by pulmonary
veins and inferior vena
cava
 Becomes fused with
the tunica adventitia of
these vessels
Serous Pericardium
Parietal layer lines the fibrous
pericardium and becomes
continuous with the visceral layer
around the roots of great vessels
Visceral layer reflected onto the
heart, forms the external layer of
the heart wall (epicardium)
The two layers are continuous
with each other at the base of the
large vessels
Pericardial cavity lies between the
two layers, that contains a thin film
of serous fluid which helps in
frictionless movement of the heart
Pericardial Sinuses
Develop during folding of
embryonic heart
Transverse sinus:
 Lies posterior to ascending aorta and
pulmonary trunk, anterior to superior
vena cava
 Communicates with the main part of
pericardial cavity at its right and left
ends
Oblique sinus:
 An inverted U-shaped blind recess
lies posterior to the heart extending
posterior to the left atrium, can be
entered inferiorly
 Produced by the reflection of
pericardium onto the pulmonary veins
and inferior vena cava
Blood Supply
Arterial Supply:
• Fibrous pericardium & the parietal layer of the
serous pericardium : Mainly supplied by
pericardiophrenic and musculophrenic arteries,
branches of internal thoracic. Also supplied by
pericardial branches of bronchial, esophageal
and superior phrenic arteries
• Visceral layer of the serous pericardium
(epicardium) supplied by the branches of the
coronary arteries
Venous drainage: Veins are tributaries of azygos
system. Pericardiophrenic veins also drain into the
internal thoracic vein
Nerve Supply
The fibrous pericardium and the parietal
layer of the serous pericardium are supplied
by the phrenic nerves.
The visceral layer of the serous pericardium
is innervated by sympathetic &
parasympathetic fibers through the
sympathetic trunks and the vagus nerves
respectively
Clinical Notes
Pericarditis & pericardial effusion
Cardiac temponade
Friction rub
Pericardiocentesis: A wide-bore needle
may be inserted through the left 5th & 6th
intercostal space near the sternum (area
of cardiac notch). Intracardial injections
are also given through this area
To be handled with care….
Heart
Hollow muscular
organ, acts as a
double pump
Conical in shape
Slightly larger than the
clenched fist
Lies free within the
pericardium
Connected superiorly
to the large vessels
Heart cont’d
Has 4 chambers: two atria
superiorly and two ventricles
inferiorly, separated from
each other by
atrioventricular and
interventricular grooves
Atria act as the receiving
chambers and the ventricles
as the pumping chambers
Right side of the heart
contains deoxygenated
blood & left side contains
oxygenated blood
External Features: Surfaces
The heart has:
Sternocostal (Anterior) surface
Diaphragmatic (Inferior) surface
Base (Posterior surface)
Apex
Sternocostal Surface
Formed mainly by
the right atrium and
the right ventricle
separated by vertical
atrioventricular
groove
The anterior
interventricular
groove separates
the right ventricle
from the left
ventricle
Diaphragmatic Surface
Formed mainly by
the right and left
ventricles separated
by posterior
interventricular
groove, and a small
part of the right
atrium, into which the
inferior vena cava
opens
Base (Posterior Surface)
Formed mainly by the
left atrium, into which
open the 4 pulmonary
veins
Quadrilateral in shape
Lies opposite the apex
Faces posteriorly,
superiorly and toward
the right shoulder
Apex
Formed by left ventricle
Directed downward, forward
and to the left
Located posterior to the left 5th
intercostal space, 7-9 cm from
the median plane and just
medial to the left midclavicular
line
Position varies slightly with the
person’s position and the phase
of respiration
Is the point of maximal
pulsation of the heart (the apex
beat can be seen as well as
palpated)
Borders of the Heart
The heart has 4 borders:
Right: Formed by the right
atrium
Left: Formed by the left auricle
above and the left ventricle
below
Inferior: Formed mainly by the
right ventricle, and the apex of
the left ventricle
Superior border is where great
vessels enter or leave the heart.
Formed by right and left auricles
and superior part of right & left
ventricle
Surface Projection of the Heart
Blood Supply of the Heart
Arterial Supply
Supplied by right & left
coronary arteries
Coronary arteries arise
from the ascending aorta
immediately above the
aortic valves
Coronary arteries and their
branches are distributed
over the surface of the
heart lying within the
subepicardial connective
tissue
Right Coronary Artery
Arises from anterior sinus
of ascending aorta
Runs between the
pulmonary trunk and right
auricle
Runs in the atrioventricular
groove
At the inferior border of the
heart turns posteriorly in
the atrioventricular groove
Anastomoses with the left
coronary artery in the
posterior interventricular
groove
Right Coronary Artery: Branches
Right conus artery
Anterior ventricular
branches: 2-3 in number,
largest is the marginal
branch
Posterior ventricular
branches, gives a branch
to atrioventricular node
Posterior interventricular
artery
Atrial branches, & artery of
the sinuatrial node which
also supplies atria
Left Coronary Artery
Larger than the right
Supplies major part of the
heart
Arises from the left
posterior aortic sinus
Runs between the
pulmonary trunk and left
auricle
Runs in the
atrioventricular groove
Divides into anterior
interventricular &
circumflex branches
Left Coronary Artery: Branches
Anterior interventricular
artery, gives a small
conus artery
Circumflex artery, gives:
Left marginal
Anterior ventricular
Posterior ventricular
Atrial branches
Variations in Coronary Arteries
In 35% of individuals, the
sinuatrial artery arises
from left coronary artery
In most of the individuals
(90%), the posterior
interventricular artery is a
branch of right coronary
artery (Right
Dominance). In 10% of
the individuals, it arises
from circumflex branch of
left coronary artery (Left
Dominance)
Coronary Artery Anastomoses
Though anastomoses do exist between
the terminal branches of the right and left
coronary arteries, but these are not large
enough to compensate for any sudden
blockage of a large branch.
A sudden blockage of the larger branches
results in myocardial infarction.
Venous Drainage
Most of the blood drains into the
right atrium through the coronary
sinus, which:
 Lies in the posterior part of the
atrioventricular sulcus
 Is continuation of the great cardiac
vein
 Opens into the right atrium to the
left of the inferior vena cava
Tributaries:
 Small cardiac vein
 Middle cardiac vein
 Posterior vein of the left ventricle
 Oblique vein of the left atrium
Venous Drainage cont’d
Anterior cardiac veins
drain directly into the
right atrium
Vena cordis minimi
(Thebesian veins)
open directly into
heart chambers
Thank U & Good Luck