Layers of the Coronary heart: Epicardium, Myocardium, Endocardium

There are three layers of the coronary heart. They’re:

• Epicardium (Outermost Layer of Coronary heart)
• Myocardium (Center Layer of Coronary heart)
• Endocardium (Innermost Layer of Coronary heart)

1. Epicardium (Outermost Layer of Coronary heart)

• The epicardium is the outermost layer of the center wall made up of mesothelium, fat, and connective tissues. It varieties the inside serous layer of the pericardium; therefore, additionally it is often known as the visceral serous pericardium. 
• Epicardium encloses the center in addition to the basis of main blood vessels rising from the center just like the aorta and the 2 vena cava. It’s also equipped by a number of coronary blood vessels, nerve fibers, and lymphatic vessels. 
• Location: Anatomically, it’s situated simply beneath the parietal serous pericardium layer of the pericardium and is in direct contact with the myocardium.

Epicardium Construction

• Histologically, it incorporates an outer layer of epithelium cells known as the mesothelium beneath which is the subserosal layer manufactured from connective tissues and a layer of fatty tissues. It may be divided into two sub-layers primarily based on their composition, viz. serous membrane and subepicardial layer. 
• The serous membrane/layer is the outer layer manufactured from mesothelial tissue. Whereas, the subepicardial layer is beneath the serous layer and is manufactured from unfastened connective tissues and adipose tissue.
• The subepicardial layer homes blood vessels, lymphatic vessels, and sympathetic in addition to parasympathetic nerves. 

Capabilities of Epicardium

• Its main operate is to supply mechanical safety to the center. 
• The serous layer secrets and techniques skinny fluid known as the pericardial fluid that lubricates the center and reduces friction through the pumping of the center. 
• Being equipped with blood and lymph vessels, it additionally helps to distribute vitamins and oxygen to the center wall and gather and transport the wastes. 

Epicardium-associated Ailments

• Epicardium itself alone will not be typically affected by illnesses; nonetheless, illnesses of pericardium or endocardium might lengthen as much as epicardium and have an effect on it.

2. Myocardium (Center Layer of Coronary heart)

• Myocardium is the center thickest muscular layer made up of cardiomyocytes. It’s accountable for the contraction and rest actions of the center. The SA (sinoatrial) and the AV (atrioventricular) nodes of the center conduction system are principally situated on this layer.   
• Location: It’s the center layer situated between the epicardium and the endocardium. 

Myocardium Construction

• Histologically, the myocardium is primarily composed of cardiac muscle cells (cardiomyocytes) (organized in a bunch known as myofibers) and some fibroblast cells. The cardiomyocytes are linked with one another by the intercalated discs. 
• Anatomically, it’s the thickest layer of the center wall. It’s thicker within the ventricular wall than within the auricular wall – significantly within the left ventricle, which is the thickest layer. The left ventricular myocardium is additional subdivided into three sub-layers, specifically subepicardial, mid-myocardial, and subendocardial layers.  
• It’s properly equipped with coronary arteries and coronary veins and cardiac lymphatic vessels. It’s also innervated with a cardiac conduction system composed of specialised cardiomyocytes.   

Capabilities of Myocardium 

• Its main operate is to contract and generate the drive for the contraction of the center wall. 
• The myocardium homes the Pacemaker cells and specialised cardiomyocytes that generate and conduct the cardiac electrical impulses.   

Myocardium-associated Ailments

The myocardium is affected by a variety of illnesses collectively known as myocardial illnesses. A few of the widespread myocardial illnesses are listed beneath. 

3. Endocardium (Innermost Layer of Coronary heart)

• The endocardium is the innermost layer of the center wall lining the inner chambers of the center and the center valves. It offers a easy floor for environment friendly blood circulate inside the center chambers. It additionally homes capillaries to provide blood to the center muscle tissues, nerve fibers, and coronary heart conduction cells. 
• Location: It’s discovered alongside the partitions of the atria and the ventricles and because the outer overlaying of the 4 coronary heart valves.  

Endocardium Construction

The endocardium is primarily composed of easy endothelial and connective tissues and a smaller fraction of easy muscle cells. Anatomically, the endocardium may be divided into three sub-layers, viz. the endothelial layer, the subendothelial layer, and the subendocardial layer.  

1. Endothelial Layer

It’s the innermost layer composed of specialised flat and easy endothelial cells. This layer makes the floor easy and permits simple blood circulate with none friction, clotting, or sticking. 

2. Sub-endothelial Layer (fibro-elastic tissue layer)

It’s the center layer composed of connective tissue containing collagen, elastic fibers, and some easy muscle cells. Resulting from its composition, additionally it is known as the ‘fibro-elastic tissue layer’. This layer offers structural assist to the endocardium. 

3. Sub-endocardial Layer

It’s the innermost layer primarily composed of connective tissues. This layer is enriched with capillaries, nerves, and cardiac conductive cells (Purkinje fiber). 

Capabilities of Endocardium

• It traces the chambers and valves of the center and offers a non-adhesive floor for environment friendly blood circulate with out adherence of platelets and blood clotting.
• It acts as a blood-heart barrier. 
• It additionally permits easy opening and shutting of the center valves. 
• It homes the Purkinje fibers and therefore helps the center’s conductive system. 

Endocardium related medical situations

The endocardium is affected by a number of medical situations known as endocardial illnesses. A few of the widespread endocardial illnesses are listed beneath. 

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