fibrous skeleton of heart & conducting system Dr.hemalata Rath ANATOMIST

1. Fibrous skeleton of heart
Dr.Hemalata
Rath
Department Of
Anatomy

2. Location
Surrounds four valves
Rings are interconnected
Functions

3. COMPLEX NETWORK OF FIBROUS BUNDLES
WITH FIBROUS AND TENDINOUS
EXPANSIONS –FIBROUS SKELETON OF
HEART
PRESENT IN THE PLANE BETWEEN ATRIA
AND VENTRICLES

4. SURROUNDS THE FOUR
VALVES
BICUSPID VALVE
TRICUSPID VALVE
PULMONARY VALVE
AORTIC VALVE
ATRIOVENTRICULAR
VALVES
SEMILUNAR
VALVES

5. • The four rings of the cardiac
skeleton surround the two
atrioventricular orifices, the
aortic orifice and opening of
the pulmonary trunks.
• These make the ANULUS
FIBROSUS.

6. Four rings:(two rings 1st & 2ndand two
coronets 3rd & 4th )
1. The left fibrous ring encircles the
bicuspid valve
2. The right fibrous ring surrounds the
tricuspid valve.
3. The pulmonary ring corresponds to the
pulmonary valve.
4. The aortic ring to the aortic valve

7. AV RING CONNECTS AORTIC RING –Trigonum
Fibrosum Dextrum (RIGHT FIBROUS TRIGONE)

8. CONNECTION B/W AORTIC RING AND
MITRAL RING –Trigonum Fibrosum
Sinistrum (LEF FIBROUS TRIGONE)

9. AORTIC CONNECTS INFUNDIBUUM –
TENDON OF INFUNDIBULUM

10. FUNCTIONS
It Allows The Muscle To Contract Against A
Rigid Base
These Fibrous Rings Support Bases Of Cusps Of
The Valves And Prevent Valves From Stretching
And Becoming Incompetent
Maintains Position Of Heart Within Pericardium
Provides Strong Mechanical Attachment To
Ventricular Muscles

11.  It Keeps The Atrioventricular Valves And The
Semilunar Valves Of The Heart Open, Without
Allowing Them To Distend.
 It Provides A Point Of Insertion For The
Bundles Of The Heart Muscle And
Effectively Separates The Atria From The
Ventricles.
 Lastly, It Acts As An Electrical Insulator By
Preventing The Radiating Electrical Impulses
From Passing Through The Atrial Muscles To The
Ventricles.
FUNCTIONS

13. Fibrous ring of tricuspid
valve -
cranial view
Left fibrous trigone - cranial
view

15. Cardiac
skeleton

17. CONDUCTING
SYSTEM OF HEART

20. • The heart is able to contract on its own
because it contains specialized cardiac
muscle tissue that spontaneously forms
impulses and transmits them to the
myocardium to initiate contraction.

22.  Pacemaker Of The Heart - Generates Impulses (About
70/Minute).
 Horseshoe-shaped Mass - Specialized Myocardial Fibres
 Situated In The Wall Of The Right Atrium In The Upper Part
Of Sulcus Terminalis Below The Opening Of Superior Vena
Cava
 Initiates The Contraction Of Cardiac Muscle Producing Heart
Beat.
(SA NODE OR NODE OF KEITH FLACK)

23. The rate at which the SA node
generates impulses is influenced
by the autonomic nervous system

24. Sympathetic
nervous system
increases firing
rate of the SA node
thus increases
heart rate

25. Parasympathetic
nervous system
decreases firing
rate of the SA node
and thus decreases
heart rate

26. Impulses Causes Contraction Of
The Atria From Superior To Inferior
Forcing Blood Into The
Ventricles
The Impulses Are Carried To
The AV Node
Impulses Pass Slowly Through
The AV Node, Which Allows
Time For The Ventricles To Fill
With Blood.

27. ATRIOVENTRICULAR NODE (AV NODE/NODE
OF TAWARA)
 It is smaller compared to the SA node.
 located in the right atrium near the junction with
the interventricular septum near the opening of the
coronary sinus.
 It conducts the cardiac impulse to the ventricle by the
atrioventricular bundle.
 The AV node acts to delay the impulses by approximately
120ms, so that atria have enough time to fully eject blood
into the ventricles

31.  Begins From AV Node,
 Crosses The AV Ring
 Runs Along The Inferior Part Of The Membranous Part
Of The Interventricular Septum
 Divides Into The Right And Left Branches Extending
Inferiorly To The Interventricular Septum
 The Bundle Of His Is The Only Means Of Conducting
Impulses From The Atria To The Ventricles
 specialized tissue of the AV node, and serves to transmit
the electrical impulse from the AV node to the Purkinje
fibres of the ventricles.
AV BUNDLE (OF HIS)

32. • Right Bundle Branch – Conducts The Impulse To The
Purkinje Fibres Of The Right Ventricle
• Left Bundle Branch – Conducts The Impulse To The
Purkinje Fibres Of The Left Ventricle.

33. PURKINJE FIBERS
 The Purkinje Fibres (Sub-endocardial
Plexus Of Conduction Cells) Are A
Network Of Specialized Cells.
 These Cells Are Located In The
Subendocardial Surface Of The Ventricular
Walls
 Rapidly Transmit Cardiac Action
Potentials From The Atrioventricular
Bundle To The Myocardium Of The
Ventricles.

35. An Excitation Signal Is Created
By The Sinoatrial (SA) Node.
Atria Contract.
AV Node
The Signal Is Delayed.
Bundle Of His
Interventricular Septum
Purkinje Fibres
Ventricles
Causing Them To Contract

38. CLINICALS

46. Tendon of
Todaro
• The tendon of Todaro is a collagenous
band within the subendocardium that
constitutes part of the fibrous skeleton
of the heart.
• It originates from the central fibrous
body.
• It is palpable in the right atrium
running from the interatrial septum
inferiorlyand to the right to the
inferomedial part of
the inferior vena caval
It forms the anterosuperior
boundary of the triangular area
of Koch.

47. Triangle of
Koch
• The triangular area of the right
atrium is bounded by the:
• Base:
– Openingof coronary sinus
• Superior:
– Tendon of Todaro
• Inferior:
– Attachment of septal leaflet of tricuspid.
– Importance in cardiovascular diseases:
used as an anatomical landmark for location of the
atrioventricular node during electrophysiology procedures such
as pacing or ablation.

49. Clinical Relevance: Artificial
Pacemaker
• An artificial pacemaker is a small electrical device
commonly fitted to monitor and correct heart rate
and rhythm. It is inserted into the chest under the
left clavicle, with wires connected to the heart via
the venous system.
• The most common indication for a pacemaker
is bradycardia. Once inserted, the pacemaker
monitors the heart rate, and only fires if the rate
becomes too slow. Pacemakers can also be used to
treat some tachycardias, certain types of heart
block and other rhythm abnormalities.