CARDIAC WALL
- The cardiac wall or myocardium is the muscular tissue of the heart, responsible for contracting & pumping blood.
Layers of the cardiac wall:
1. Epicardium:
- The outermost layer.
- It is the visceral layer of the serous membrane.
- Made of mesothelial cells, below them is a layer of adipose and connective tissue.
- Nerves and blood vessels that supply the heart are found in the epicardium.
- Function: provides a protective outer covering for the heart.
3. Endocardium:
- Inner layer
- Consists of endothelial cells ,which are simple squamous epithelial tissue layer and a thin layer of loose connective tissue.
- lines the cavity and valves.
- “pericardium”
- Serous pericardium
- Fibrous pericardium.
* The atria have relatively thin walls compared to the ventricles, because they primarly recieve blood rather than pumping it.
2. Myocardium:
- Function:
- conduct Action potential
- contraction
- The middle and thickest layer.
- It is a muscular layer that enables heart layers
- Made of cardiac muscle cells (cardimyocytes)
- Have a single nucleus in the center of the cell, which helps to distinguish them from skeletal muscle cells that have multiple nuclei dispersed in the periphery of the cell.
- The cardiomyocytes are connected with each other through the intercalated discs.
Atrial muscle
- The atrial myocardium can be divided into:
- Superficial layer: Extends over both atria and thicker along its anterior compared to the posterior aspect.
- Deep layer: Contained looped fiber or annular fibers that passes to the artioventricul boundary also encircle the venous orifices.
Ventricular muscle:
- Subepicardial layer:
- Runs horizontaly about the surface of the right atrium.
- // longitudinally from the left atrium.
- At the Apex both ventricle subepicardial muscle forms a vortex of the heart. They curve around and forms the inner subendocardi
- Middle- Present in left ventricle and interventricular septum.
- Subendocardium: Contributes to formation of the trabeculae carneae and papillary muscles.