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Cardiovascular System:
Heart
Chapter 12
Heart Anatomy
Wall: Composed of 3
layers – endocardium,
epicardium,
myocardium.
 Epicardium – thin
serous membrane
outermost surface of
the heart (same as
the visceral
pericardium).
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Myocardium – thick
middle layer, cardiac
muscle – allows for
contraction of the heart.
Endocardium – simple
squamous over a layer of
connective tissue –
smooth innermost layer
allows blood to move
easily through (valves are
formed by a fold in this
layer – it is a double layer
with connective in
between.
Myocardium
Histology
Special Features. . .
 Musculi
pectinati – muscular ridges
with in the atria.
 Crista Terminalis – smooth portion
with in atria.
 Trabeculae carneae – columns of
“meat”
External Anatomy
2 atria – superior posterior
 2 ventricles – anterior inferior
 Auricles – flaplike extensions of the atria –
anterior between the atria and ventricles.
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Blood Flow - vessels
To the heart (superior vena cava, inferior
vena cava, coronary sinus) – into the right
atrium.
 (4) Pulmonary veins – from the lungs into
the left atrium.
 From the heart (Aorta from the left
ventricle to the body and Pulmonary Trunk
from the right ventricle to the lungs).
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More Anatomy . . .
A large coronary sulcus runs around the
heart separating the atria from the
ventricles.
 Right and Left coronary arteries supply
blood to cardiac tissue and leave off of the
aorta where it leaves the heart.
 Great cardiac vein drains tissue on the left
side and small cardiac vein drains the right
margin.
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Chambers and Valves
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Right atrium – fed by the superior and inferior
vena cava and the coronary sinus.
Left atrium – fed by the pulmonary veins
Atria separated by the interatrial septum.
The atria open into the ventricles through the
atrioventricular canals.
Right ventricle opens into the pulmonary trunk.
Left ventricles open to the aorta.
Ventricles are separated by the interventricular
septum.
Atrioventricular Valves
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Keep blood from flowing back into the atria.
Composed of cusps and flaps.
Bicuspid (Mitral) is on the left side.
Tricuspid is on the right side.
Papillary muscles are attached by the chordae
tendonae.
Semilunar valves: Aorta and pulmonary trunk –
from the ventricles to the main blood vessels.
They have free inner boarders which meet in the
center to block blood flow.