Anatomy of the heart lecture.pptx

1. HEART
ANATOMY

7. • Plan : 1 Introduction in angiology.
• 2 The arterial system.
• 3 The structure of arteries.
• 4 The structure of veins.
• 5 The structure of heart
• 6 Circulation.

8. 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

9. 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)

10. 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

11. Two surfaces:
1. 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.
2. Diaphragmatic surface is formed by the ventricles – chiefly by the
left ventricle, directed backwards and downwards, and rests upon
the central tendon of the diaphragm.
Three borders:
1. Right border - vertical, is formed entirely by right atrium.
2. Left border - round, is mainly formed by the left ventricle and partly
by the left auricle.
3. Inferior border - horizontal, is formed by the right ventricle and
cardiac apex

12. Four grooves:
1. Coronary sulcus (circular sulcus) which marks the division between
atria and ventricles, contains the trunks of the coronary vessels and
completely encircles the heart.
2. Interatrial groove －separates the two atria and is hidden by
pulmonary trunk and aorta in front.
3. 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 incisura.

13. 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

14. 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

15. FRONTAL SECTION

16. ATRIA OF THE HEART
• Atria - receiving chambers of the heart
o Receive venous blood returning to heart
o Separated by an interatrial septum (wall)
o Foramen ovale - opening in interatrial septum in fetus
o 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

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
o Contains components of the conduction system
• Right ventricle pumps blood into the pulmonary trunk
• Left ventricle pumps blood into the aorta
o 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

19. Structure of Heart Wall
• Left ventricle – three times
thicker than right
• Exerts more pumping force
• Flattens right ventricle into a
crescent shape

20. 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
• Composed of dense connective tissue
• Main point of insertion for cardiac muscle
• Blocks direct spread of electrical impulses

21. HEART VALVES
• Heart valves ensure unidirectional blood flow through the heart
o Composed of an endocardium with a connective tissue core
• Two major types
o Atrioventricular valves
o Semilunar valves
• Atrioventricular (AV) valves lie between the atria and the ventricles
o R-AV valve = tricuspid valve
o 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
o Prevent prolapse of valve back into atrium

22. 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
o“Lub” - closing of atrioventricular valves
o“Dub”- closing of semilunar valves

23. 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
Valve of pulmonary trunk
• Guards the orifice of pulmonary trunk
• Has three semilunar cusps – each with free border

24. POSTERIOR VIEW

25. 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

26. CONDUCTING SYSTEM OF THE HEART

27. 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

28. Innervation
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.
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

29. MAJOR VESSELS OF THE HEART
Vessels returning blood to the heart include:
• Superior and inferior venae cavae
oOpen into the right atrium
oReturn deoxygenated blood from body cells
• Coronary sinus
oOpens into the right atrium
oReturns deoxygenated blood from heart muscle (coronary veins)
• Right and left pulmonary veins
oOpen into the left atrium
oReturn oxygenated blood from lungs

30. MAJOR VESSELS OF THE HEART
Vessels conveying blood away from the heart include:
• Pulmonary trunk
oCarries deoxygenated blood from right ventricle to lungs
oSplits into right and left pulmonary arteries
• Ascending aorta
oCarries oxygenated blood away from left atrium to body organs
oThree major branches
 Brachiocephalic
 Left common carotid
 Left subclavian artery

31. BLOOD FLOW THROUGH THE HEART

32. Pathway of Blood
Through the Heart
and Lungs

33. Coronary Circulation
• The functional blood supply to the heart muscle itself
• R and L Coronary arteries are 1st branches off the ascending aorta
• Coronary sinus (vein) empties into R. atrium
• Collateral routes ensure blood delivery to heart even if major vessels
are occluded

34. Coronary Circulation - Arteries
• Right Coronary Artery
o Supplies blood to
 Right atrium and posterior surface of both
ventricles
o Branches into the
 Marginal artery - extends across surface of R.
ventricle
 Posterior interventricular artery
• Left Coronary Artery
o Supplies blood to
 Left atrium and left ventricle
o Branches into
 Circumflex artery
 Anterior interventricular artery

35. Coronary Circulation - Veins
Coronary sinus
• Vein that empties into right atrium
• Receives deoxygenated blood from:
o Great cardiac vein - on anterior surface
o Posterior cardiac vein
 Drains area served by circumflex
oMiddle cardiac vein
 Drains area served by posterior interventricular
artery
o Small cardiac vein
 Drains blood from posterior surfaces of right
atrium and ventricle