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3. POSITION
Lies within the pericardium in middle mediastinum
Behind the body of sternum and the 2nd to 6th costal
cartilages
In front of the 5th to 8th thoracic vertebrae
A third of it lies to the right of median plane and 2/3 to
the left
Anterior to the vertebral column, posterior to the sternum
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
5. EXTERNAL CHARACTERISTICS
A hollow muscular organ, pyramidal in shape , somewhat
larger than a closed fist; consists of four chambers (right and
left atria, right and left ventricles)
Cardiac Apex is formed by left ventricle and is directed
downwards and forwards to the left. It lies at the level of the
fifth left intercostal space, 1~2cm medial to the left
midclavicular line (9cm from the midline)
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
6. EXTERNAL CHARACTERISTICS
The apex beat 【point of maximum impulse (PMI)】,
is the furthermost point outwards (laterally) and
downwards (inferiorly) from the sternum at which the
cardiac impulse can be felt.
Lateral and/or inferior displacement of the apex beat
usually indicates enlargement of the heart, called
cardiomegaly
Approximately the size of your fist
Wt. = 250-300 grams
Cardiac base is formed by the left atrium and to a small
extent by the right atrium. It faces backward, upward
and to the right
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
7. Two surfaces
Sternocostal surface
is formed mainly by the right atrium
and right ventricle, and a lesser portion of its left is formed by
the left auricle and ventricle. It is directed forwards and
upwards
Diaphragmatic surface is formed by the ventricles-
chiefly the left ventricle, directed backwards and
downwards, and rests upon the central tendon of the
diaphragm
Three borders
Right border-vertical, is formed entirely by right atrium
Left border-round, is mainly formed by the left ventricle
and partly by the left auricle
Inferior border-horizontal, is formed by the right ventricle
and cardiac apex
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
8. Four grooves
Coronary sulcus (circular sulcus) which marks the division
between atria and ventricles, contains the trunks of the coronary
vessels and completely encircles the heart
Interatrial groove -separates the two atria and is hidden by
pulmonary trunk and aorta in front
Interventricular grooves - anterior and posterior, mark the
division between ventricles (which separates the RV from the LV),
the two grooves extend from the base of the ventricular portion to a
notch called: the cardiac apical incisure
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
9. COVERING OF THE HEART
Pericardium – a double-walled sac around the heart
Composed of:
A superficial fibrous pericardium
A deep two-layer serous pericardium
The parietal layer lines the internal surface of the fibrous
pericardium
The visceral layer or epicardium lines the surface of the heart
They are separated by the fluid-filled pericardial cavity called the
pericardial cavity
Protects and anchors the heart
Prevents overfilling of the heart with blood
Allows for the heart to work in a relatively friction-free environment
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
10. Interatrial septum
Located between right and left atria
Contains fossa ovalis
Interventricular septum Located between right and left ventricles
upper membranous part
thick lower muscular part
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
13. LAYERS OF THE HEART WALL
Epicardium – visceral pericardium
Myocardium – cardiac muscle layer
forming the bulk of the heart
Endocardium – endothelial layer of the
inner myocardial surface
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
16. ATRIA OF THE HEART
Atria - receiving chambers of the heart
Receive venous blood returning to heart
Separated by an interatrial septum (wall)
Foramen ovale - opening in interatrial septum in fetus
Fossa ovalis - remnant of foramen ovale
Each atrium has a protruding auricle
Pectinate muscles mark atrial walls
Pump blood into ventricles
Blood enters right atria from superior and inferior venae cavae and
coronary sinus
Blood enters left atria from pulmonary veins
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
17. Left auricle-projecting to the
right, pectinate muscles in wall
Four inlets-four orifices of
pulmonary veins open through the
posterior wall
One outlet-left atrioventricular
orifice, blood leaves through left
atrioventricular orifice to left
ventricle
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
18. VENTRICLE OF THE HEART
Ventricles are the discharging chambers of the heart
Papillary muscles and trabeculae carneae muscles mark
ventricular walls
Separated by an interventricular septum
Contains components of the conduction system
Right ventricle pumps blood into the pulmonary trunk
Left ventricle pumps blood into the aorta
Thicker myocardium due to greater work load
Pulmonary circulation supplied by right ventricle is a much low pressure
system requiring less energy output by ventricle
Systemic circulation supplied by left ventricle is a higher pressure system
and thus requires more forceful contractions
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
20. Left ventricle
It’s wall is three times thicker
than that of right ventricle
One inlet-left atrioventricular
orifice
One outlet-aortic orifice
Two parts-divided by anterior
cusps of mitral valve
Inflow tract-rough walls
Outflow tract – aortic
vestibule smooth area
leading to aortic orifice
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
21. SEPTUMS/FIBROUS SKELETON
Interatrial septum
Located between right and left atria
Contains fossa ovalis
Interventricular septum Located between right and left ventricles
upper membranous part
thick lower muscular part
Fibrous skeleton
Fibrous rings that surround the atrioventricular, pulmonary, and
aortic orifices
Left and right fibrous trigons
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
23. HEART VALVES
Heart valves ensure unidirectional blood flow through the heart
Composed of an endocardium with a connective tissue core
Two major types
Atrioventricular valves
Semilunar 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
Chordae tendineae anchor AV valves to papillary muscles of
ventricle wall
Prevent prolapse of valve back into atrium
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
24. SEMILUNAR HEART VALVES
Semilunar valves prevent backflow of blood into the ventricles
Have no chordae tendinae attachments
Aortic semilunar valve lies between the left ventricle and the aorta
Pulmonary semilunar valve lies between the right ventricle and
pulmonary trunk
Heart sounds (“lub-dup”) due to valves closing
“Lub” - closing of atrioventricular valves
“Dub”- closing of semilunar valves
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
25. Tricuspid valve
Guards right atrioventricular orifice
Three triangular cusps: anterior, posterior and septal, the base
of cusps are attached to fibrous ring surrounding the
atrioventricular orifice
Chordae tendineae -fine, white, connective tissue cords,
attach margin of cusps to papillary muscles
Mitral valve
Guards left atrioventricular orifice
Two triangular cusps-anterior and posterior with Similar
structures to those of right
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
26. Valve of pulmonary trunk
Guards the orifice of pulmonary trunk
Has three semilunar cusps – each with free border
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
29. CONDUCTING SYSTEM OF THE
HEART
Cardiac muscle tissue has intrinsic ability to:
Generate and conduct impulses
Signal these cells to contract rhythmically
Conducting system
A series of specialized cardiac muscle cells
Sinoatrial (SA) node sets the inherent rate of
contraction
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
30. CONDUCTING SYSTEM OF THE
HEART
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
31. INNERVATION
Heart rate is altered by external controls
Nerves to the heart include:
Visceral sensory fibers
Parasympathetic branches of the vagus
nerve
Sympathetic fibers – from cervical and
upper thoracic chain ganglia
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
32. Sinuatrial node (SA node)
Called the pacemaker cell (P cell)
Located at the junction of right atrium and superior vena cava,
upper part of the sulcus terminalis, under the epicardium
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
33. Atrioventricular node (AV node)
Located in the lower part of interatrial septum just above the
orifice of coronary sinus, under the endocardium
Lower part related to membranous part of interventricular septum
Atrioventricular bundle (AV bundle)
Passes forward through right fibrous trigon to reach inferior border
of membranous part
Divides into right and left branches at upper border of muscular
part of interventricular septum
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
34. MAJOR VESSELS OF THE HEART
Vessels returning blood to the heart include:
Superior and inferior venae cavae
Open into the right atrium
Return deoxygenated blood from body cells
Coronary sinus
Opens into the right atrium
Returns deoxygenated blood from heart muscle (coronary
veins)
Right and left pulmonary veins
Open into the left atrium
Return oxygenated blood from lungs
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
35. MAJOR VESSELS OF THE HEART
Vessels conveying blood away from the heart include:
Pulmonary trunk
Carries deoxygenated blood from right ventricle to lungs
Splits into right and left pulmonary arteries
Ascending aorta
Carries oxygenated blood away from left atrium to body
organs
Three major branches
Brachiocephalic
Left common carotid,
Left subclavian artery
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
36. BLOOD FLOW THROUGH THE HEART
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
37. PATHWAY OF BLOOD THROUGH THE
HEART
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)
38. DISORDERS OF THE HEART
Coronary artery disease
Atherosclerosis – fatty deposits
Arteriosclerosis - hardening of the arteries
Angina pectoris – chest pain
Myocardial infarction – blocked coronary artery
Silent ischemia – no pain or warning
Fibrillation - irregular heart beat; may occur in either
atria or ventricles
Lecture on Anatomy of the Heart ( drnnamanisamuel@gmail.com)