Download Chambers, conduction system and nerves of the heart

Chambers, conduction system and
nerves of the heart
Dr. Muddanna S. Rao
Associate Professor
Department of Anatomy, Faculty of Medicine,
Kuwait University, Kuwait
Chambers, conduction system and nerves
of the heart
Objectives:
1. Differentiate between chambers of heart
2. Describe salient features of right and left atria and ventricles.
3. Relate structure and functions of heart valves
4. Describe the position of heart valves and relate with projection of heart
sounds
5. Describe the conduction system of heart.
6. Describe the components of cardiac plexus and innervation pattern of heart
Chambers of the heart
Sternocostal surface
Base and diaphragmatic surface
Left ventricle
Left ventricle
Right ventricle
On the external surface of human heart four chambers of the heart can be
identified - 2 Atria (Left atrium and right atrium) and 2 ventricles (Left ventricle and
right ventricle.
Chambers of the heart (opened)
In schematic section of human heart, four chambers are shown-Left atrium, right atrium, Left
ventricle and right ventricle. Right atrium receives the deoxygenated blood through superior and
inferior vena cava. Superior vena cava brings the blood from upper limbs, head and neck region,
and inferior vena cava from trunk and lower Limbs. Blood from right atrium flows into right
ventricle through right atrioventricular orifice. From the right ventricle blood flows through
pulmonary trunk into left and right lungs for oxygenation(pulmonary circulation). Left atrium
receives the oxygenated blood from left and right lungs through pulmonary veins. Through left
atrioventricular / mitral orifice blood flows into left ventricle, and from here it flows through
ascending aorta for distribution to various parts of the body (Systemic circulation).
Right Atrium
Right auricle
Interatrial septum
Superior vena cava
Right atrioventricular
orifice
Limbus fossa ovalis
Fossa ovalis
Musculi pectinati
Cresta terminalis
Opening of coronary sinus
Left ventricle
Inferior vena cava
Valve of inferior vena cava
and coronary sinus
Right atrium receives deoxygenated blood from various parts of the body through SVC and IVC
and coronary sinus. Interior of the right atrium shows thin walled smooth posterior part, Sinus
venarum and rough anterior part. The rough part consists of a muscular ridge, called cresta
terminalis (corresponding to sulcus terminalis on the external surface) and muscular ridges
arising from it - musculi pectinati. In the interatrial septum, Limbus fossa ovalis, bounds the
fossa ovalis, an oval depression. Coronary sinus opens into right atrium between opening of the
IVC(Guarded and is guarded by its valve), and atrioventricular orifice.It is guarded by valve of
coronart sinus.
Tricuspid (Right atrioventricular)valve
Right
atrium
Right
Ventricle
Cusps of tricuspid valve
The tricuspid (right atrioventricular) orifice is guarded by tricuspid valve.This valve has anterior,
posterior and septal cusps.The cusps are thin double foildings of endocardium. The chordae
tendinae arising from the papillary muscles are attached to the fee margin and ventricular
surface of the cusp and prevent the prolapse of the cusps into atria during systole. They prevent
backflow of blood into atria during ventricular systole.
Right Ventricle
Supraventricular crest
Pulmonary trunk
Pulmonary valve
Infundibulum
Right atrium
Interventricular septum
Right ventricle
Tricuspid
(right atrioventricular
valve
Muscle ridges
Chordae tendinae
Septomarginal band
(Moderator band)
Papillary muscles
Muscle bridges
Interior of the right ventricle shows rough inflow part and smooth outflow partinfundibulum. Infundibulum is separated from rest of the ventricle by supraventricular
crest, a muscular ridge. The rough part has the cardiac muscles arranged in the form
of papillary muscles (Anterior, posterior, and septal), ridges and bridges. Chordae
tendinae connect the papillary muscles to cusps of tricuspid orifice. Septomarginal
band stretches from interventricular septum to the base of anterior papillary muscle.
Infundibulum leads to pulmonary trunk, guarded by pulmonary valve.
Pulmonary Valve
Pulmonary Valve
Pulmonary sinus
Similunar Cusps
The pulmonary orifice is guarded by pulmonary valve. It has 3 semilunar cuspsAnterior, right posterior, left posterior. Pulmonary valve prevent backflow of blood
during ventricular diastole.
Left Atrium
Arrow in the left
atrioventricular
(bicuspid) orifice
Left auricle
Left Atrium
Pulmonary
veins
Left Atrioventricular
(bicuspid) Valve
Interatrial
septum
(Region of
fossa ovalis)
Interior of the left atrium shows thin walled smooth posterior part, and rough anterior
part- auricle. In the interatrial septum, impression of limbus fossa ovalis, and fossa
ovalis, (which are seen in right atrium) can be seen. Left atrium receives oxygenated
blood from lungs through four pulmonary veins. Blood leaves the atrium through left
atrioventricular orifice (Mitral orifice) to reach left ventricle.
Bicuspid/mitral (Left atrioventricular)valve
Left atrium
Chordae
Tendinae
Left ventricle
Cusps of mitral valve
Papillary
muscle
The bicuspid (left atrioventricular) orifice is guarded by mitral valve. They prevent
backflow of blood into atria during ventricular systole. This valve has anterior and
posterior cusps. The chordae tendinae, attached to the fee margin and ventricular
surface of the cusp, prevent their prolapse into left atrium during systole.
Chordae tendinae
Left Ventricle
Arrow in the left
atrioventricular
(bicuspid) orifice
Papillary muscle
Left Atrium
Aortic valve
Left Ventricle
Left Atrioventricular
(bicuspid) Valve
Thick wall
Aortic
vestibule
Left ventricle receives oxygenated blood from left atrium through left atrioventricular
orifice, and pumps the blood into aorta through arortic orifice. Interior of the left
ventricle shows rough in flow part and smooth outflow part- aortic vestibule. The
rough part has the cardiac muscles arranged in the form of papillary muscles
(Anterior and posterior), ridges and bridges. Chordae tendinae connect the cusps of
the valve to papillary muscle. Aortic vestibule leads to ascending aorta, guarded by
aortic valve.
Aortic Valve
Aortic valve
Aortic sinus
Coronary
artery
Semilunar
cusp
The aortic orifice is guarded by aortic valve. It has 3 semilunar cusps-right, left and
posterior. Left and right coronary arteries arise from left and right aortic sinus
respectively. Aortic valve prevent backflow of blood during ventricular diastole.
Interatrial septum
Interatrial septum
Interatrial septum
(From right side)
Limbus fossa ovalis
Fossa ovalis
Interatrial septum
(From left side)
The interatrial septum is the thin partition between left and right. Fossa vovalis and
limbus fossa vovalis can be seen on the right side of the septum
Interventricular septum
Membranous part of interventricular septum
Interventricular
septum
Left ventricle
Right ventricle
Left ventricle
Right ventricle
Muscular part of interventricular septum
The interventricular septum, the partition between left and right ventricles, has
membranus and muscular parts. Interventricular septum is convex towards right
ventricle. Cavity of the right ventricle is crescentic and left ventricle is circular in cross
section. Wall of left ventricle is 3 times thicker than right ventricle.
Valves of the heart seen from Above
during diastole and systole
Diastole
Anterior
Systole Left
Right
Posterior
A
R
L
L
R
P
Pulmonary
orifice
Aortic
orifice
Tricuspid orifice
Bicuspid
(Mitral)orifice
During diastole, ventricles (Left and right) relax,
the right and left atrioventricular orifice open
allowing the blood to flow from atria to ventricles.
During this time pulmonary and aortic orifices are
closed, preventing the backflow of blood into the
ventricles.
Bicuspid
(Mitral)orifice
Tricuspid orifice
During systole, ventricles (Left and right)
contract, the right and left atrioventricular orifice
are closed preventing back flow of blood into to
atria. During this time pulmonary and aortic
orifices are open, allowing the flow of blood into
pulmonary trunk and aorta.
Surface projection of of heart orifices
Site of auscultation of valve
Sites of heart sound
A- Aortic
P - Pulmonary
T - Tricuspid
M – Mitral
Cardiac orifices
a- aortic
p - Pulmonary
t - Tricuspid
m - Mitral
Location of valve
A
p
a
P
t m
T
M
The right and left atrioventricular,aortic and pulmonary orifices can be depicted on the
surface of chest along an oblique line from left 3rd sternocostal joint(costal
cartilage) to right sternal margin at 4th intercostal space. Pulmonary orifice on left
3rd costal cartilage, Aortic orifice on body of the sternum at level of 3rd intercostal
space. Left atrioventricular (Mitral orifice) on left sternal margin across the 4th
sternocostal joint (costal cartilage). Right atrioventricular orifice on the right margin of
sternum at 4th intercostal space.
Sites of heart sound
A- Aortic
P - Pulmonary
T - Tricuspid
M – Mitral
Cardiac orifice
a- aortic
p - Pulmonary
t - Tricuspid
m - Mitral
Location of valve
Sites of heart sounds
Site of auscultation of valve
A
p
a
P
t m
T
M
When the blood flows through left and right atrioventricular, aortic and pulmonay
orifice, they produce the heart sounds, which can be heard better on certain points on
the chest wall. The left atriovetriculr (mitral) valve sound best heard in the left 5th
intercostal space, in the midclavicular line. The right atriovetriculr (tricuspid) valve
sound best heard along the left sternal margin at 6th sternocostal joint. Aortic and
pulmonary valve sound along the right and left margin of sternum at the level of the
second intercostal space respectively.
Position of heart valves and projection of heart sounds
Site of auscultation of valve
A
p
a
T
p M
A
P
t m
Location of valve
T
M
When the blood flows through left and right atrioventricular, aortic and pulmonay
orifice, they produce the heart sound, which can be heard better in the direction of
blood flow.
Conducting system of the Heart
Left branch of bundle of His
and its branches on left side
of interventricular septum
Sinuatrial node
Bundle of His
Left branch
of His
Left ventricle
Right branch of bundle
of His on right side of
interventricular septum
Atrioventricular node
Conducting system of heart is specialized cardiac muscle tissue, concerned with generation and propagation of cardiac
impulses. This system is responsible for highly rhythmic contraction and relaxation of heart muscle. Autononic nerves influence
the cnducting system. Conducting system includes Sinuatrial node(SA node),atrioventricular node(AV node),bundle of His, left
and right branches of bundle of His and their further branches, purkinje fibers.SA node is pacemaker of the heart, is situated in
the right atrial wall close to superior vena caval entry. AV node is situated posteroinferior region of interatrial septum, near the
opening of coronary sinus. Bundle of his passes through the fibrous skeleton of the heart and reaches the right side of
interventricular septum, where it divides into left and right branches. Right runs on the right side of interventricular septum and
divides into several branches and end in purkinje fibers, which supply the ventricular muscles and papillary muscles. Left
branch runs on the left side of interventricular septum and divides into its branches finally end in purkinje fibers, suppling left
ventricular and papillary muscles.
Conducting system of the Heart
Impulses (arrows) initiated at the SA node, located at the superior end of the sulcus
(internally, crista) terminalis, are propagated through the atrial musculature to the AV
node. Impulses (arrows) received by the AV node, in the inferior part of the interatrial
septum, are conducted through the AV bundle and its branches to the myocardium.
The AV bundle begins at the AV node and divides into right and left bundles at the
junction of the membranous and muscular parts of the interventricular septum.
Parasympathetic nucleus
of vagus nerve
Innervation of the Heart
Cervical ganglia
of sympathetic
chain
Vagus nerve
Cardiac branches of
vagus nerve
Cardiac branches
from sympathetic
ganglion
Thoracic
sympathetic
ganglia
Trachea
Superficial cardiac
plexus on arch of
aorta
Deep cardiac
plexus
Thoracic segments of
spinal cord
Heart
Innervation of the Heart
Heart is innervated by Autonomic nervous system. Sympathetic,
parasympathetic and cardiac afferent nerve fibers form the superficial cardiac
plexus (on the arch of the aorta) and deep cardiac plexus (behind the ascending
aorta and pulmonary trunk, in front of bifurcation of trachea). Nerves from these
plexus supply the heart.
Sympathetic: Preganglionic sympathetic fibers arise from the lateral horn of
upper 5-6 thoracic spinal segments of the spinal cord. Post ganglionic fibers run
through cardiac branches of cervical sympathetic and superior thoracic ganglion
and reach the cardiac plexus. They innervate the SA node, AV node and
coronary arteries. Sympathetic stimulation causes increased heart rate , impulse
conduction, force of contraction and increased blood flow through coronary
arteries.
Parasympathetic:
Preganglionic
parasympathetic
fibers
arise
from
parasympathetic nucleus of vagus nerve and pass through the carddiac braches
of vagus nerve and reach the cardiac plexus. Postsynaptic parasympathetic cell
bodies are located in the atrial wall, interatrial septum near SA and AV nodes and
along the coronary arteries. Parasympathetic stimulation slows the heart rate,
reduces the force of contraction, constricts the coronary artery.
Ref:
1.Clinically oriented Anatomy ,6th Ed. By Keith L. More, Arthur F. Dalley and
Anne M.R. Agur
1.Grays Anatomy, 38TH Ed. By Peter L. Williams et al
Thank you