Download The Heart

The Heart
YC Wong, PhD 王雲川
The University of Hong Kong
[email protected]
Scope
• Overview of anatomy of the heart
• Surface markings and gross anatomical
structure
• Vascular system of the heart
• Impulse conducting system
• Histology of the heart
Location and surface markings
Sternal
angle
• Located in middle mediastinum 纵隔
• Locate the sternal angle
• Point one: right 3rd costal cartilage 1
cm from sternum border
• Point 2: 6th costal cartilage, 1 cm from
sternum
• Point 3: 5th left intercostal space just
medial to mid clavicular line
• Point 4: 2nd left intercostal space at
the border of sternum
• Join the 4 points to mark the outer
shape of the heart
The Pericardium 心包膜
•
•
•
•
•
•
Fibrous capsule enclosing the heart
Separated by pericardial cavity filled with fluid
To reduce the friction of heart during pumping
Lined by serous pericardium 浆膜心包
Subdivided into parietal and visceral layers
The parietal layer closely adheres to fibrous pericardium 纤维
心包; the visceral layer reflected on the outer surface of
heart, the external limit of epicardium 心外膜, lined by
mesothelium 间皮
• Perforated only at the roots of major vessels
• Reflections of serous pericardium forms transverse sinus 横窦
and oblique sinus 斜窦
The Pericardium 心包膜
Trans Sinus
R. Pulmonary V
L pulmonary V
Oblique Sinus
Anatomy of the Heart
Right atrium
Left auricle
Left
ventricle
Right ventricle
Apex
• Located in middle mediastinum
• Surrounded by pericardium
• Apart from attachment to
major vessels, the rest is
basically free within pericardial
cavity
• Three surfaces: sternocostal
surface, diaphramatic surface
and base, i.e. the posterior
surface
• The apex 心尖 of the heart is
directed forward, downward
and to the left
Four Chambers
•
•
•
Right Atrium
Left atrium
•
•
Pulmonary v
Aortic v
Mitral v
•
Tricuspid v
•
Right ventricle
Left ventricle
•
Divided by vertical septa to form 4 chambers
Right atrium and left atrium, separated by
interatrial septum
Right ventricle and left ventricle, separated by
interventricular septum
Right atrium and right ventricle is guarded by a
valve, the tricuspid valve, 三尖瓣
Left atrium and left ventricle is guarded by
mitral valve 二尖瓣
Deoxygenated blood returns to right atrium
then to right ventricle which is pumped to the
lungs via pulmonary trunk, guarded by
pulmonary valve 肺动脉瓣
Oxygenated blood from the lungs enters the
left atrium, then to left ventricle
This blood is pumped through aorta guarded by
aortic valve 主动脉瓣
Right atrium 右心房
Right auricle
Superior vena cava
Musculi pectinati
Fossa
ovale
Inferior vena
cava with valve
• Receive blood from superior
vena cava 上腔靜脈
• Inferior vena cava 下腔靜脈
• Venous blood from the heart,
the coronary sinus 冠状窦
• Interior surface, musculi
pectinati 梳状肌
• Fossa ovale 卵圆窝, on
interatrial septum
• Crista terminalis 界嵴
• Right auricle 心耳, an
extension from atrium,
irregular surface
• Location of sinoatrial node 竇
房結at junction with superior
vena cava
Patent foramen ovale
•
•
•
•
Fairly common
Hidden condition
No obvious symptoms
Left atrium pressure higher
than right, the potent
opening is physiologically
closed
• Reason for the opening to
stay patent, and not fused
afterbirth remains unclear.
• No treatment is needed in
most cases
Atrial Septal Defect (ASD)
• Hole in interatrial septum
• Allow left atrial blood
(oxygenated) to enter right
atrium (lower pressure)
• Increased work load of right
ventricle
• Small hole, no significant
effect
• Medium or large hole may
require surgical repair
Ventricular Septal Defect
• Hole in interventricular
septum
• Can be in different location
along the septum
• Blood flow from left ventricle
through hole to right venricle
• Increased right ventricle work
load
• Increase pulmonary pressure,
pulmonary hypertension
• Require surgical intervention
Right ventricle 右心室
Anterior cusp
Septal cusp
Chordae
tendinease
Posterior cusp
of tricuspid
valve
Papillary muscle
Moderator band
• Wall much thicker than
atrium
• Separated from atrium by
tricuspid valve
• With anterior, posterior
and septal cusps
• Papillary muscle for the
attachment of heart valve
tendons, chordae
tendineae 腱索
• Moderator band 节制带
• Pumps blood into
pulmonary trunk
• Guarded by semilunar
valves 半月瓣
Left atrium 左心房
• The wall is thin, like right
atrium,
• Located mainly at the
posterior surface
• A large portion is formed
by absorption of major
blood vascular wall
during development
• Extension of left auricle
to the stenocostal
surface
• Smooth interior surface
receive 4 pulmonary
veins from the lungs
Left ventricle 左心室
Mitral valve
Chordae tendinease
Papillary muscle
• Wall very thick, twice as thick as right
ventricle
• Separated from left atrium by mitral
valve, with only two leaflets
• Responsible for systemic circulation
• Interior surface is rough with trabeculae
carneae心肉柱, papillary muscles, but
no moderator band
• Chordae tendineae 腱索, to strengthen
the leaflets of the valve
• Pumps blood out through aorta
• Guarded by aortic valve, semilunar valve
• The part of heart immediately below the
aortic orifice is known as aortic
vestibule
Cardiac skeleton 心骨架
Fibrous ring
of pulm trunk
Mitral valve ring
• Not a true skeleton
• Fibrous connective tissues located between
atria and ventricles
• One ring between right atrium and right
ventricle
• The other between left atrium and left
ventricle
Fibrous ring • Forms an 8 shape figure
at aortic valve
• For the attachment of atrial fibres and
ventricular fibres as well as attachment of
tricuspid and mitral valves
• Extensions of fibrous connective tissues to the
roots of pulmonary trunk and aorta for
Tricuspid
valve ring
attachment of semilunar valve leaflets
• No direct connection/contact between atrial
and ventricular muscle fibres
Heart valves 心瓣
• Atrio-ventricular valves 房室瓣
– Tricuspid valve: between right atrium and right ventricle
• Three leaflets anchor through tenon-like structure, chordae
tendineae
– Mitral valve: between left atrium and left ventricle
• Two leaflets
• Pulmonary valve: at the junction of pulmonary trunk
with right ventricle
– Semilunar valve: three leaflets of half moon shape
• Aortic valve: junction of aorta with left ventricle
– Semilunar valve with three leaflets of half moon shape
– Origin of coronary arteries from aortic sinus
The coronary arteries 冠狀動脈
• Left coronary artery: larger, from left
posterior aortic sinus. It enters
atrioventricular groove and gives rise
to:
L coronary a
L circumflex b
R coronary a
Anterior
interventricul
ar branch
Marginal b
Posterior
interventric
ular branch
– Anterior interventricular branch,
anastomoses with posterior
interventricular branch from right
coronary artery
– Left circumflex branch, anastomosing
with right coronary artery
• Right coronary artery: from anterior
aortic sinus runs between pulmonary
trunk and right auricle, and atrioventricular groove
– Marginal branch
– Posterior interventricular branch
Variations of coronary arteries
A. Left coronary artery dominant
B. Only one coronary artery, the right one is missing
C. Circumflex artery is arising from right coronary artery
Coronary arteries and heart
diseases
• Crucial for heart health
• Anastomoses between artery branches
though occur, but most branches supply a
secluded area
• Blockage of vessels or branches of vessels
often results in death of cardiac muscle fibres
in the affected, myocardiac infarction 心肌梗
塞
• Serious cases result in death
Venous drainage of the heart
Coronary sinus
Great cardiac
vein
Small
cardiac vein
Middle cardiac vein
Coronary sinus
Middle cardiac vein
• Venous blood returns to right
atrium via coronary sinus
• It is a continuation of great
cardiac vein running parallel
to anterior interventricular
artery
• Small and middle cardiac
veins are tributories of
coronary sinus
• Anterior cardiac vein empties
directly into right atrium
Impulse
conducting
system of
heart
Impulse conducting system
心臟之傳導系統
• Specialized cardiac muscle to regulate the rhythm of heart
• Sinoatrial node , 窦房结 pace-maker of the heart, to set the
pace of heart beat
• Initiates atrial heart muscle contraction as well as spreading the
signals to AV node 旁室結
• Atrioventricular node passes the singals to Purkinje fibres
• Two branches extended out from here, known as bundle of HIS
• Bundles of His run down along the sides of interventricular
septum and give off Purkinje fibres
• Purkinje fibres spread contraction signals to ventricular cardiac
fibres, to start ventricular contraction
• Cardiac arrththmia 心律失常
PA X-ray of the Heart
Auscultation points of heart sounds
Aortic valve
Right atrium
Tricuspid
valve
Right ventricle
• A for aortic valve
• P for pulmonary
valve
• T for tricuspid valve
• M for mitral valve
Histology of the heart
With three basic layers
Endocardium 心內膜
Myocardium 心肌膜
Epicardium 心外膜
Endocardium
• Inner most
• Endothelium
• Sub-endothelial
connective tissue
• Sub-endocardial layer
which may contain
conducting system of
heart, Purkinje fibres
Myocardium
• Substantially thicker
• Contains cardiac muscle
• With intervening collagen
tissue and smaller vessels
• Atrial walls are much
thinner than myocardium in
ventricles
• Muscles are attached to
cardiac skeleton between
atria and ventricles
• Typical cardiac fibre
morphology with striations
and intercalated disks
Epicardium
• Rich in fat (A; adipose
tissue)
• Free surface covered by
mesothelial (M) cells
• Connective tissue
• Blood vessels, coronary
vessels
M
Heart valves 心瓣
• Aortic valve: semilunar valve with three leaflets,
each is shaped as half-moon
• Pulmonary valve: same as aortic valve with three
leaflets
• Left atrioventricular valve or mitral valve: two
leaflets reinforced with tendinous cords known as
chordae tendineae, to prevent eversion
• Right atrioventricular valve or tricuspid valve:
three leaflets, also reinforced with chordae
tendineae
Structure of heart valves
•
•
•
•
Attached to fibrous cardiac skeleton
Formed as a flap extending from tunica intima
Normally avascular in nature
Supported by a core of irregular dense
connective tissue continuous with cardiac
skeleton
• Covered on both side by endothelial cells
Impulse conducting system
(structure)
• Sinuatrial (SA) node, pacemaker, specialized
group of cardiac fibres located at junction
between superior vena cava and right atrium
– Smaller than ordinary fibres
• Atrioventricular (AV) node
• AV bundle of His, further divide to left and right
bundles and then into subendocardial fibres
• Purkinje fibres
– Larger in diameter, paler staining and carry impulses
to ordinary cardiac muscle in ventricles
– Rich in sarcoplasm, scarce myofibrils
Purkinje fibres (P)
Myocardium
Summary
•
•
•
•
•
•
Surface anatomy of the heart
Structure of the heart
Common septal defects
The coronary vessels
Impulse conducting system
Histological organization of the heart
End