The cardiac skeleton is made of dense connective tissue. inside the heart situated several structure the cord-like tendons are The Chordae tendineae, in the ventricles of the heart are found papillary muscles. in The heart is an oval depression known as fossa ovalis, also found a well-defined fibromuscular ridge called crista terminalis. and a specialized bundle of neurons or SA node is situated in the upper part of the wall of the right atrium, there is another one node known as Atrioventricular node or AV node, both node are part of the electrical conduction system of the heart
The Chordae tendineae are tendinous cords found in the right and left ventricles of the heart. that connect to the tricuspid valve and the mitral valve in the heart, function of the chordae tendineae is preventing backflow of blood into the atria and limiting atrioventricular valves capacity to “flap” back into the corresponding atrium.
The papillary muscles are located in the ventricles of the heart that anchors the cusps of the atrioventricular valves; each ventricle has an anterior and a posterior papillary muscle, papillary muscles are five in totel number.
The fossa ovalis is an oval depression located in the atrium of the heart on the lower part of the septum of the wall between right and left atrium, During fetal development in embryonic heart, the foramen ovale allows blood to pass from the right atrium to the left atrium
The crista terminalis is a well-defined fibromuscular ridge formed by the junction of the sinus venosus and primitive right atrium, crista terminalis is generally a smooth-surfaced that provides the origin for the pectinate muscles.
The SA node is situated in the upper part of the wall of the right atrium, it’s natural pacemaker of the heart and made up of a specialized bundle of neurons and spontaneously generates an electrical impuls
atrioventricular node or AV node is The electrical relay station between the atria and the ventricles, also a part of the electrical conduction system of the heart
Electrical Conduction System
The electrical signal travels through the network of conducting cell, signals from the Sinoatrial node must pass through the atrioventricular node to the atrioventricular bundle which divides into the Left bundle branch and the Right bundle branch in which stimulus travels, it is farther divides into the Purkinje fibers that carry the electrical signal,
The arterial blood supply of the conducting system
mainly the conducting system of heart supply by the right coronary artery but all the arteries of the right bundle branch derived from left coronary arteries.The sinuatrial node was supplied by the right coronary artery more frequently in 70% of cases) than by the left coronary artery and both coronary arteries this node was supplied in 30% of cases )