Anatomy Bones and Muscles · MU Pleven

91. Structure of the heart wall. Fibrous skeleton of the heart

Covers the three layers of the cardiac wall: the epicardium, the thick cardiomyocyte-based myocardium with its atrial and ventricular muscle arrangements, and the endocardium lining the chambers and valves. It then describes the cardiac skeleton, a fibrous framework made of the four valve rings, the left and right fibrous triangles, the infundibular tendon and the membranous interventricular septum, with its role in directing conduction.

Inside: 3 sections · 2 labelled pictures · 13 flashcards · 4 min

Topic 90 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 507 words (4 min of reading), with 13 flashcards.

In this note

  1. CARDIAC WALL
  2. Layers of the cardiac wall:
  3. CARDIAC SKELETON

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 than 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.
  • The heart is covered by: “pericardium”
  1. 1. Serous pericardium
  2. 2. Fibrous pericardium.

* The atria have relatively thin walls compared to the ventricles, because they primarily receive 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 (cardiomyocytes).
  • 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:

  1. 1. Superficial layer: Extends over both atria and thicker along its anterior compared to the posterior aspect.
  2. 2. Deep layer: Contained looped fiber or annular fibers that passes to the atrioventricular boundary also encircle the venous orifices.

Ventricular muscle:

  1. 1. Subepicardial layer:
  • Runs horizontally 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 subendocardium.
  1. 2. Middle- Present in left ventricle and interventricular septum.
  2. 3. Subendocardium: Contributes to formation of the trabeculae carneae and papillary muscles.

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