the heart yc wong, phd 王雲川 the university of hong kong [email protected]
TRANSCRIPT
The Heart YC Wong, PhD 王雲川
The University of Hong [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
• 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
Location and surface markings
Sternal angle
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
R. Pulmonary V L pulmonary V
Trans Sinus
Oblique Sinus
Anatomy of the Heart• 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
Right ventricle
Left ventricle
Right atriumLeft auricle
Apex
Four Chambers• 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
Right ventricle
Left atrium
Left ventricle
Tricuspid v
Mitral v
Pulmonary v Aortic v
Right atrium 右心房• 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
Superior vena cava
Inferior vena cava with valve
Fossa ovale
Right auricle
Musculi pectinati
• 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
Patent foramen ovale
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• 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
Anterior cusp
Septal cusp
Posterior cusp of tricuspid valve
Papillary muscle
Chordae tendinease
Moderator band
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• 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
Mitral valve
Chordae tendinease
Papillary muscle
Cardiac skeleton 心骨架• 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• Forms an 8 shape figure• 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 attachment of semilunar valve leaflets
• No direct connection/contact between atrial and ventricular muscle fibres
Mitral valve ring
Tricuspid valve ring
Fibrous ring of pulm trunk Fibrous ring
at aortic valve
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:– 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 atrio-ventricular groove– Marginal branch– Posterior interventricular branch
L coronary a
L circumflex b
Anterior interventricular branch
Posterior interventricular branch
R coronary a
Marginal b
Variations of coronary arteries
A. Left coronary artery dominantB. Only one coronary artery, the right one is missingC.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
• 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
Coronary sinus
Great cardiac vein
Small cardiac vein
Middle cardiac vein
Coronary sinus
Middle cardiac vein
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
• A for aortic valve• P for pulmonary
valve• T for tricuspid
valve• M for mitral valve
Aortic valve
Tricuspid valve
Right atrium
Right ventricle
Histology of the heartWith three basic layersEndocardium 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
vesselsM
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