Library · Anatomy
Endocardium
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The endocardium is the heart's inner lining: the layer facing the chambers, in contact with the blood. It is extremely thin, a single row of endothelial cells, the same ones that line the inside of blood vessels.
Just beneath it lies a supporting layer, the subendothelial layer, with loose elastic tissue, bundles of collagen (the protein that provides strength), nerves, and the occasional vessel.
The heart wall has three layers that, by their embryonic origin, correspond to the three layers of a vessel: the epicardium corresponds to the adventitia, the myocardium to the media, and the endocardium to the intima.
And one detail is worth noting: between the endocardium and the muscle sits the subendocardium, and through it runs the conduction system, which carries the electrical impulse. The heart's wiring runs just under the inner lining.
In brief
The endocardium is the innermost layer of the heart: a single layer of endothelial cells lining the chambers.
Beneath it, the subendothelial layer contains loose elastic tissue, collagen bundles, nerves, and an occasional vessel.
The three layers of the heart wall are embryologically equivalent to those of a vessel: epicardium, myocardium, and endocardium correspond to adventitia, media, and intima.
Between the endocardium and the myocardium, the subendocardium houses the impulse conduction system.
The heart's wiring runs just under the inner lining.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingHistology, Heart, StatPearlsPublished
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