Myocardium (muscle tissue heart) - definition and function
The MUSCLE tissue that forms the walls of the HEART. Myocardial cells are unique in their structure, blending muscle and NERVE structures so they can both contract and conduct electrical impulses. Myocardial cells thus can contract independent of external stimulation. The myocardial fibers of the atria have a different configuration from those of the ventricles. The CORONARY ARTERIES provide an extensive network to supply blood to the myocardium, which requires about 70 percent of the blood’s oxygen. With increasing age, fibrous and fatty tissue tends to infiltrate the myocardium, somewhat reducing its effectiveness.
| CONDITIONS THAT CAN AFFECT THE MYOCARDIUM | |
|---|---|
| CARDIOMYOPATHY | CONGENITAL ANOMALY |
| ISCHEMIC HEART DISEASE | MICROINFARCTION |
| MYOCARDIAL INFARCTION | MYOCARDITIS |
CORONARY ARTERY DISEASE (CAD) is the most significant threat to the myocardium, as occlusions in the coronary arteries deprive the myocardium of blood and thus oxygen. When the consequence is MYOCARDIAL INFARCTION, CARDIAC ARREST can result.
For further discussion of the myocardium within the context of cardiovascular structure and function, please see the overview section “The Cardiovascular System.”
See also ENDOCARDIUM; HEART FAILURE; PERICARDIUM.
