Editing Endocardium (section)

{{short description|Innermost layer of tissue lining the chambers of the heart}}
{{Infobox anatomy
| Name        = Endocardium
| Latin       = endocardium
| Image       = Gray493.png
| Caption     = Interior of right side of heart
| Image2      =
| Caption2    =
| Precursor   =
| System      =
| Artery      =
| Vein        =
| Nerve       =
| Lymph       =
}}
[[File:Blausen 0470 HeartWall.png|thumb|Illustration depicting the layers of the heart wall including the innermost endocardium]]

The '''endocardium''' ({{plural form}}: '''endocardia''') is the innermost layer of [[Tissue (biology)|tissue]] that lines the chambers of the [[heart]]. Its [[Cell (biology)|cells]] are [[embryology|embryologically]] and biologically similar to the [[endothelium|endothelial]] cells that line [[blood vessel]]s. The endocardium also provides protection to the valves and heart chambers.<ref>{{cite journal |last1=Brutsaert |first1=D. L. |last2=Andries |first2=L. J. |title=The endocardial endothelium |journal=American Journal of Physiology-Heart and Circulatory Physiology |date=October 1992 |volume=263 |issue=4 |pages=H985–H1002 |doi=10.1152/ajpheart.1992.263.4.H985 |pmid=1415782 }}</ref>

The endocardium underlies the much more voluminous [[myocardium]], the muscular tissue responsible for the contraction of the heart. The outer layer of the heart is termed [[epicardium]] and the heart is surrounded by a small amount of fluid enclosed by a fibrous sac called the [[pericardium]].<ref>{{cite book |last1=Tran |first1=Dan B. |last2=Weber |first2=Carly |last3=Lopez |first3=Richard A. |title=StatPearls |date=2025 |publisher=StatPearls Publishing |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK545195/ |chapter=Anatomy, Thorax, Heart Muscles |pmid=31424779 }}</ref>