Download 1439573491-2 Heart anatomy

HEART ANATOMY
DR. EMAD ABU ALRUB
AAUJ
HEART ANATOMY
Approximately the size of your fist
Wt. = 250-300 grams
Location
In the mediastinum between the lungs
Superior surface of diaphragm
⅔’s of it lies to the left of the midsternal line
Anterior to the vertebral column, posterior to
the sternum
HEART ANATOMY
Figure 18.1
COVERINGS 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
PERICARDIAL LAYERS OF THE HEART
Figure 18.2
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
HEART ANATOMY
External markings
Apex - pointed inferior region
Base - upper region
Coronary sulcus
Indentation that separates atria from ventricles
Anterior and posterior interventricular sulcus
Separates right and left ventricles
Internal divisions
Atria (superior) and ventricles (inferior)
Interventricular and interatrial septa
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
GROSS ANATOMY OF HEART: FRONTAL SECTION
Figure 18.4e
VENTRICLES 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
EXTERNAL HEART: ANTERIOR VIEW
Figure 18.4b
STRUCTURE OF HEART WALL
Left ventricle – three
times thicker than
right
Exerts more
pumping force
Flattens right
ventricle into a
crescent shape
Figure 18.7
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
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
FIBROUS SKELETON
Surrounds all four valves
Composed of dense connective tissue
Functions
Anchors valve cusps
Prevents overdilation of valve openings
Main point of insertion for cardiac muscle
Blocks direct spread of electrical
impulses
HEART VALVES
CONDUCTING SYSTEM
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
CONDUCTING SYSTEM
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
EXTERNAL HEART: POSTERIOR VIEW
Figure 18.4d
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
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 ventricle to
body organs
Three major branches
Brachiocephalic
Left common carotid,
Left subclavian artery
BLOOD FLOW THROUGH THE HEART
Figure 18.6
PATHWAY OF BLOOD THROUGH THE HEART AND LUNGS
Figure 18.5
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
CORONARY CIRCULATION - ARTERIES
Right Coronary Artery
 Supplies blood to
Right atrium and posterior surface of both ventricles
 Branches into the
Marginal artery - extends across surface of R. ventricle
Posterior interventricular artery
Found in posterior interventricular sulcus
Left Coronary Artery
 Supplies blood to
Left atrium and left ventricle
 Branches into
Circumflex artery
Anterior interventricular artery
Found in anterior interventricular sulcus
Connected with posterior interventricular artery via arterial
anastomoses
CORONARY CIRCULATION: ARTERIAL
SUPPLY
Figure 18.7a
CORONARY CIRCULATION - VEINS
Coronary sinus Vein that empties into right atrium
Receives deoxygenated blood from:
Great cardiac vein - on anterior surface
Posterior cardiac vein
Drains area served by circumflex
Middle cardiac vein
Drains area served by posterior interventricular
artery
Small cardiac vein
Drains blood from posterior surfaces of right atrium
and ventricle
CORONARY CIRCULATION: VENOUS
SUPPLY
Figure 18.7b
MICROSCOPIC ANATOMY OF HEART MUSCLE
Cardiac muscle cells
Short, striated, branched, and interconnected
The connective tissue endomysium acts as both
tendon and insertion
Intercalated discs anchor cardiac cells together
and allow free passage of ions
Heart muscle behaves as a functional syncytium
Many mitochondria (25% of total volume)
MICROSCOPIC ANATOMY OF HEART MUSCLE
Figure 18.11
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