Download - CVS 1 - Anatomy of the Heart_2014
Anatomy of the Heart
Dr. Asma’ HassanAnatomy DepartmentPusat Pengajian Sains
PerubatanUniversiti Sains Malaysia
Objectives
4. Describe the anatomy of the heart with regard to its
4.1. location and external features
4.2. internal features of the chambers
4.5. surface anatomy
Divisions of Mediastinum
Transverse thoracic plane• Anterior - sternal angle • Posterior - lower border of T4
I - Superior mediastinum
II - Inferior mediastinum: Anterior
Middle (pericardium & heart) Posterior
• The heart, pericardium and root of great vessels occupy themiddle mediastinum
Pericardium
Pericardium is a fibroseroussac surrounding the heart andthe root of great vessels
It consists of 2 components:1 - Fibrous pericardium2 - Serous pericardium
Pericardium1 - Fibrous Pericardium• a tough connective tissue • the outer layer which defines
the boundaries of middle mediastinum
• enclose heart & roots of great vessels
• fused with tunica adventitia of great vessels
• fused with central tendon of diaphragm
Blood supply: • internal thoracic artery and
its branches
Pericardium
2 - Serous Pericardium• It is a thin layerConsists of 2 parts:• Parietal layer
– lines the inner surface of fibrous pericardium
• Visceral layer (= epicardium) – lines the heart and forms
its outer covering– also lines the beginnings of
great vessels• Both layers are continuous
around roots of great vessels
Pericardium
2 - Serous Pericardium• Both parietal and visceral
layers are continuous around roots of great vessels
• Reflections of serous pericardium occur in 2 locations:
• Superior – surrounding the arteries, aorta and pulmonary trunk
• Posterior – surrounding the inferior and superior venae cavae and pulmonary veins
Nerve supply to Pericardium
1. Fibrous Pericardium• phrenic nerve
2. Serous pericardium• Parietal layer* – phrenic nerve
(C3, 4, 5) produces the pain in inflammation of pericardium
• Visceral layer – insensitive to pain
• Pain from heart (i.e. from muscle and vessels)
- sympathetic nerves
Pericardial cavity
• The potential space between parietal and visceral layers ofserous pericardium
• It contains a thin film of fluid• The potential space allows the movement of the heart
Pericardial Sinuses• A reflection of serous
pericardium forming recess or sinus
• Located dorsal to the heart
1 - Oblique pericardial sinus 2 - Transverse pericardial sinus
1 - Oblique pericardial sinus • a cul-de-sac between 2 left & 2 right pulmonary veins & IVC• “cardiac bursa”• posteriorly is the oesophagus• can be entered inferiorly
left right
Pericardial Sinuses
2 - Transverse pericardial sinus
• due to dorsal mesentery breaks down during development
• It is anterior to superior vena cava
• It is located posterior to ascending aorta and pulmonary trunk
• There is a communication from right to left sides
- The two sinuses are not continuous
Pulmonary trunk
Pulmonary veins
The Heart• Position – surfaces and margins
• Skeleton of the Heart
• Chambers of the Heart
Surfaces of the Heart
1. Anterior or sternocostal surface• right ventricle • both atria
2. Posterior surface or base• left atrium
3. Inferior / diaphragmatic surface• left ventricle • right ventricle
RV
RA
LA
LV
RV
LV
LA
Borders of the Heart
1. Right border• right atrium
2. Inferior border • right ventricle • left ventricle
3. Left border • left ventricle • auricle of left atrium
4. Apex • left ventricle
Apex Beat of the Heart
• Formed by inferolateral partof left ventricle
• Located slightly medial to surface projection of apex
• Corresponds to the left 5th intercostal space in adults
• A distance of 9 cm from median plane
Sternocostal Projections of Valves of the Heart
• sternocostal projections of valves do not necessarily correspond to the best site of auscultation
• this is due to deep location of heart in the chest
• auscultation is usually performed by listening through a stethoscope
ooo
o
O = sternocostal projectionX = point of auscultationArrows show blood flow
X
X
X
X
Sternocostal Projections of Valves & Auscultation Point
Valve Sternocostal Projection
Point of Auscultation
Pulmonic 3rd c.c., left sternal border
2nd left ICS, just lateral to sternal angle
Aortic 3rd ICS, left sternal border
2nd right ICS, just lateral to sternal angle
Mitral 4th c.c., left sternal border
5th left ICS, 9 cm lateral to midline
Tricuspid 4th ICS, midsternal 4th left ICS, just lateral to sternum
ICS- intercostal spacec.c. – costal cartilage
Layers of the Heart Wall
1. Epicardium (external layer)– Visceral layer of serous
pericardium– Smooth, slippery texture
to outermost surface
2. Myocardium– 95% of heart is cardiac
muscle
3. Endocardium (inner layer)– Smooth lining for
chambers of heart, valves and continuous with lining of large blood vessels
Skeleton of the Heart
• a pair of conjoined fibrous rings• forms a figure of 8• consists of dense connective
tissue• bound the following orifices:
– Atrioventricular orifice: separate muscles of atria
from ventricles
– Pulmonary orifice– Aortic orifice
Provides attachment for:• myocardial tissue • cusps of valvesFunction - keep orifices patent
External features of Right Atrium
• Main cavity• Right auricle
• Right auricle – overlies ascending aorta
• Sulcus terminalis – between right auricle and
right atrium
Internal features of Right Atrium
Crista terminalis• found on the inside which
forms ridge
Rough part: pectinate muscles• located in front • from crista terminalis to
auricle• derived from primitive atrium
Smooth part• derived from sinus venosus• posterior to crista terminalis
Internal features of Right Atrium
Interatrial septum • separate right atrium from left
atrium Fossa ovalis • a shallow depression• site of foramen ovale• floor of fossa is from the
persistent septum primum
Limbus fossa ovalis • upper margin• remnant of septum secundum
*
Interatrial septum
Openings of Right Atrium
1. Superior vena cava• opens in upper part of atrium• at the level of 3rd costal
cartilage
2. Inferior vena cava (IVC)• opens into lower part of
atrium• at level of 5th costal cartilage
Opening of Right Atrium
3. Right atrioventricular (tricuspid) orifice • located anterior to IVC opening• orifice is guarded by tricuspid
valve
4. Opening of coronary sinus• between right atrioventricular &
IVC orifices
Opening of coronary sinus
External features of Right Ventricle
• Atrioventricular groove seen• It forms most of the anterior
surface of heart• Also forms the inferior border
of heart• Superior part tapers to form
the conus arteriosus (or infundibulum)
• Conus arteriosus ends in the pulmonary trunk (arterial)
conus arteriosus
pulmonary trunk
Internal features of Right Ventricle
Trabeculae carneae• irregular muscular elevations
3 Papillary muscles:• Posterior, anterior and septal
papillary muscles
• Papillary muscles in the ventricles are connected to chordae tendineae
Fx: help to stabilise AV valves during ventricular contraction
Papillary
muscle
Trabeculae
carneae
Internal features of Right Ventricle
Septomarginal trabecula(moderator band)• extends from interventricular
septum to the base of anterior papillary muscle
• contain right bundle branch of atrioventricular bundle
Thick interventricularseptum - crescent shapecavity
Septomarginal
trabecula
Chordae tendineae
Internal features of Right Ventricle
Chordae tendineae• fibrous cords which connect
papillary muscle to valve cusps• it is attached to adjacent sides of
2 valve cusps
Conus arteriosus / Infundibulum • the funnel shape part that
leads to pulmonary trunk(arterial)
• It is thin and smooth
pulmonary artery
conus arteriosus
Right atrioventricular valve
• also known as tricuspid valve
• it guards the rightatrioventricular orifice
• located at the 4th intercostalspace
• has 3 valve cusps that isposterior, anterior and septal
Valves in systole
A
SP
Each heart valve has 2 or 3 cusps
Cusps of the Heart valves• The atrial surfaces are smooth• The ventricular surfaces are
irregular and rough
Attachment of valve cusps:• Its base attached to the fibrous
rings of heart skeleton
• The free edges and ventricular surfaces attached to the chordae tendineae
Functions of chorda tendineae:• prevent cusps from being driven
into right atrium when ventriclecontracts
• prevent regurgitation of blood
Chordae tendinae
Valve cusp
Pulmonary valve of Right Ventricle
Pulmonary valve• guards the pulmonary orifice• located at the 3rd costal
cartilage• has 3 semilunar cusps i.e.
– right, anterior and left
Pulmonary sinus • spaces at origin of
pulmonary trunk
SA
Pulmonary artery
pulmonary valve
External features of Left Atrium
• Main cavity• Left auricle – forms the left heart
border
• The size is smaller than right atrium but has thicker wall
• Forms most of the base of heart• Has a large area of smooth–
walled atrium• Has small muscular auricle called
pectinate muscleLA
External features of Left Atrium
• Left atrium forms the anterior wall of oblique sinus
• There are 4 pulmonary veins entering LA:– 2 superior pulmonary veins– 2 inferior pulmonary veins
Internal features• Left atrioventricular orifice is
guarded by the mitral valve• The mitral valve has 2 cusps:
anterior and posterior LA
Pulmonary veins
AP
Internal features of Left Ventricle
• forms the apex of the heart
Compare to right ventricle:• walls are 3x thicker• circular cavity• well-developed & numerous
trabeculae carneae• has 2 large papillary muscles:
anterior and posterior• no septomarginal trabecula
Chordae tendineae• similar to that of right
ventricle
Mitral valve of Left Ventricle
Mitral / bicuspid valve• guards left atrioventricular
orifice (between LA and LV)• located at 4th costal cartilage• has 2 cusps:
– anterior: large– posterior
Valve cusps• similar in structure to
tricuspid valve of rightventricle
AP
Anterior papillary
muscle
Posterior papillary muscle
Internal features of Left Ventricle
Aortic vestibule: • located below aortic orifice• it is a smooth part
3 Aortic sinuses: • superior to each valve• dilations of aortic wall
Right coronary artery• originate from the right
aortic sinus
Left coronary artery• originate from the left
aortic sinus
Aortic sinus
Aortic vestibule
Aortic valve of Left Ventricle
Aortic valve • guards aortic orifice
(between LV and aorta)• located at 3rd intercostal
space• has 3 semilunar cusps:
right, posterior and left
Right ventricle Left ventricle
Papillary muscles
3 2
Smooth wall part
conus arteriosus / infundibulum
aortic vestibule
Septomarginal trabecula
present absent
Shape of cavity crescent circular
Name of valves tricuspid: 4th ICS pulmonary: 3rd c.c.
mitral: 4th c.c. aortic: 3rd ICS
Thickness of wall
thin 3x thicker
Trabeculae carneae
less prominent well-developed, numerous
Difference between Right and Left Ventricles
Tricuspid and Bicuspid Valves
• chordae tendineae are inserted from one papillary muscle always into two free edges adjacent cusps
• the pull of chordae tendineae on cusps approximates their free edges
• this simultaneously prevents cusps to be inverted into atrium
Atrioventricular (AV) valves Semilunar valves
Right AV (tricuspid)- separates the right atrium from the right ventricle- prevent backflow into atrium
Pulmonary valve- separates the right ventricle from the pulmonary arteries- prevents backflow after ventricular contraction
Left AV (bicuspid / mitral)- separates the left atrium from the left ventricle- prevents backflow into atrium
Aortic valve- separates the left ventricle from the aorta- prevents backflow after ventricular contraction
The Heart Valves
References
1. Clinically oriented anatomy - Keith Moore
2. Gray’s anatomy for students- Drake
3. Clinical anatomy - Snell