1. The Myocardium: Chambers, valves and
innervation
Prof. Abdulameer Al-Nuaimi

2. Right atrium
Right Auricle overlaps the beginning of Ascending Aorta
Fossa ovalis bounded by the limbus (on posterior wall)
Musculi Pectinati, Crista terminalis, Sulcus terminalis
Orifice of inferior vena cava is guarded by a thin fold of endocardium anteriorly (valve of inferior vena cava)
Opening of coronary sinus also guarded by an endocardial flap

3. Right Ventricle
Interventricular septum bulges into its cavity Making it crescentic in cross section
The inside wall is covered by interlacing muscle bands, the Trabeculae carneae except superiorly where the wall is smooth in the Infundibulum
Septomarginal band is near the apex
Atrioventricular orifice is postero inferiorly
Tricuspid valve
Cusps surfaces are rough at the margins and ventricular surfaces
Chordae tendineae are attached to two small papillary muscle
Pulmonary semilunar valves are two anterior and one posterior. In the middle of the free margin of each valve is a thickened nodule

5. Rectangular chamber forms the base of the heart.
Left Atrium
Rectangular chamber forms the base of the heart.
Left auricle overlaps the left side of the pulmonary trunk.
Posterior wall is smooth, it receives four pulmonary veins.
Left atrioventricular orifice lies in the anterior wall.
The posterior wall is related to the oesophagus, Left bronchus and descending aorta
Opened Lt. atrium posteriorly
Lt. atrium
Ant. View
Post. View

6. Left ventricle
Has conical cavity
Lies mainly behind the Rt. Ventricle.
Lined by muscular ridges except the Vestibule.
Atrioventricular valve (Bicuspid valve) located posteriorly, the anterior cusp is larger.
Cusps are attached to tendinous cords to papillary muscles.
Aortic orifice is located behind and to the right of the pulmonary orifice.
One anterior and two posterior semilunar valves guarding the aortic orifice.
Anterior and posterior interventricular sulci mark the attachment of the interventricular septum.
The interventricular septum is very thick except for a thin membranous portion between the vestibule and the infundibulum.

7. Left Ventricle

8. Fibrous skeleton of the heart
The fibrous skeleton of the heart is a dense connective tissue made of collagen frame. It includes a fibrous rings of the mitral, tricuspid, pulmonary and aortic valves, and connections between these individual fibrous rings. The fibrous skeleton merges with the interventricular septum.
Functions 1- electrically isolate the atria from the ventricles. Also, 2- it provides rigidity to prevent the dilatation of individual valves or outflow tracts. 3- it provides a point of attachment for valve leaflets and the myocardium.
In youth, collagen structure is free of calcium and is quite flexible. With aging some calcium can accumulate on this skeleton and contributes to the delay of the depolarisation wave in old patients that can take place from the AV node and the bundle of His.

9. The atrioventricular rings serve for the attachment of
the muscular fibres of the atria and ventricles, and for
the attachment of the bicuspid and tricuspid Valves. The cardiac muscles gets origin and insertion to the opposite sides of the valve rings. Thus the myocardium extends from the fibrous skeleton in a series of spirals that progress to the apex.
(Front)
Rear

10. The atrioventricular valves tend to lie in the same plane as each other: this faces anteriorly, slightly to the left and inferiorly
The aortic valve lies superior and to the right of the atrioventricular valve plane
The pulmonary valve lies anterosuperior to the aortic valve, to its left but roughly at right angles

11. Right
Left

13. Conductive system of the heart
The system is formed of specialised cardiac muscle cells which are difficult to distinguish from cardiac muscle. It comprises the Sinuatrial (SA) node, the Atrioventricular (AV) node, the Atrioventricular bundle (AV bundle, or bundle of His), its right and left branches and a terminal subendocardial plexus (Purkinje fibres).
This system initiates the complex
cardiac muscle contractions comprising
the cardiac cycle, and controls its
regularity.
Conductive system of the heart
Purkinje fibres

14. Thank You