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ANATOMY OF
HEART
Thorax
• Thorax is the superior part of the trunk
between the neck and abdomen.
• It extends below the neck to the diaphragm.
• It contains the primary organs of respiratory
and cardiovascular system
• A typical human rib cage consists of 24 ribs,
the sternum, costal cartilages, and the 12
thoracic vertebrae.
• All ribs are attached in the back to the thoracic
vertebrae.
• The upper seven are true ribs, are attached in the front
to the sternum by means of costal cartilage. Due to
their elasticity they allow movement when inhaling
and exhaling.
• The 8th, 9th, and 10th ribs are called false ribs, and join
with the costal cartilages of the ribs above.
• The 11th and 12th ribs are known as floating ribs, as
they do not have any anterior connection to the
sternum.
• The spaces between the ribs are known as intercostal
spaces; they contain the intercostal muscles, nerves,
and arteries.
• The thoracic cavity is divided into three major
spaces.
• The central/median compartment called
mediastinum houses the conducting
structures(esophagus,trachea,major blood
vessels and most importantly heart).
Pericardium
There are two layers to the pericardial sac:
1. the fibrous pericardium and
2. the serous pericardium.
• The serous pericardium, in turn, is divided into
two layers, the parietal pericardium and
visceral pericardium
Heart
The wall of each heart chamber consists of
1. Endocardium:thin internal layer of
endothelium
2. Myocardium: thick, middle layer composed
of cardiac muscle
3. Epicardium:thin external layer formed by the
visceral layer of serous pericardium
• The heart has four chambers:
• Right and left atria
• Right and left Ventricles
Atrium
Right atrium
• The superior vena cava opens at the level of R.
3rd costal cartilage and inferior vena cava at 5th
costal cartilage.
• The right atrium opens into the R. ventricle
thru Tricuspid valve
• Receives poorly oxygeneted blood from
superior vena cava, inferior vena cava and
coronary sinus
Left atrium
• The pairs of right and left pulmonary veins
enter the posterior aspect of atrium.
• The left atrium opens into L. ventricle thru
Bicuspid or mitral valve.
• Receives rich oxygenated blood from
pulmonary veins from the lungs
Ventricles
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•
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•
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Right ventricle:
Receives the deoxygenated blood from the
atrium
And thru R. and L. pulmonary arteries pumps
blood to the lungs
Left ventricle:
Receives the oxygenated blood from the atrium
And thru Aorta pumps blood to the systemic
circulation
Left ventricle more thicker than the right ventricle
Papillary muscles
• Papillary muscles are nothing but the conical
muscular projections from the myocardium of
the heart
• They support, strenghthen and responsible for
the opening and closure of the cuspid valves.
• They area attached to the cuspid valves
through tendinous cords called chordae
tendinae
Conducting system of the heart
• Conducting system of the heart consists of the
cardiac muscle cells, SA and AV nodes,
purkinje fibres and Bundle of His.
Sinuatrial node(SA)
• It is located antero-laterally just deep to epicardium at
the jucnction of Superior Venacava and R.atrium.
• It is the pacemaker of the heart, initiating and
regulating the impulses for contraction.
• It is a small collection of nodal tissue and specialized
cardiac muscle fibres.
• It could be stimulated or inhibited by the sympathetic
or parasympathetic division
Atrio-Ventricular Node(AV)
• Smaller collection of nodal tissue than SA
node.
• Located in the posteroinferior region of the
interatrial septum.
Bundle of His
• AV bundle- the AV node passes the signal from
atrium to the ventricles thru AV bundle, which is
the only bridge between the atrial and ventricular
myocardium.
• Av bundle divides into R. and L. bundle
• These bundles proceed on each side and then
ramify into purkinje fibres
• These purkinje fibres on both side stimulate the
papillary muscles and respective ventricles.
END