Heart wall layers

Shape

Blunt/Cone

Variation

active > sedentary; decreases after 65.

Position

in mediastinum, ~7–9 cm left of sternum, medial to midclavicular line.

Epicardium

thin outer surface; Visceral layer of serous pericardium, composed of mesothelial cells and fat and connective tissues

Myocardium

thick middle, contractile; Muscle layer, composed of cardiomyocytes.

Endocardium

smooth inner lining, aids easy blood flow; Lines inner surface of heart chambers and valves, composed of a layer of endothelial cells, and a layer of subendocardial connective tissue.

Fibrous pericardium

prevents overdistension, anchors the heart

Serous pericardium

parietal (lines fibrous), visceral (covers surface).

Pericardial fluid

reduces friction.

Heart wall layers

Epicardium- Myocardium- Endocardium- Fibrous pericardium- Serous pericardium- Pericardial fluid

Pericardium

is a double-layered sac surrounding the heart, providing protection and reducing friction during heartbeats.

Fibrous Pericardium

Tough, fibrous outer layer.

Fibrous Pericardium

Prevents overdistension and anchors the heart within the mediastinum.

Fibrous Pericardium

Attached to: Great vessels (e.g., aorta) at the top. Diaphragm at the bottom.

Serous Pericardium

Inner layer, made of simple squamous epithelium.

Parietal and Visceral Pericardium

Serous Pericardium is subdivided into?

Parietal Pericardium

Lines the fibrous pericardium.

Visceral Pericardium (Epicardium)

Covers the heart’s surface