Heart
A micrograph and an illustration demonstrate the three layers of the heart; the rectangle on the illustration indicates the region shown in the micrograph. The endocardium, the innermost lining of the heart, contacts the blood. The myocardium is the middle, muscular layer of the heart. The outermost layer of the heart is a serous membrane, the epicardium (visceral pericardium). 10x
Components
A micrograph and an illustration demonstrate the three layers of the heart; the rectangle on the illustration indicates the region shown in the micrograph. The endocardium, the innermost lining of the heart, contacts the blood. The myocardium is the middle, muscular layer of the heart. The outermost layer of the heart is a serous membrane, the epicardium (visceral pericardium). 10x
Endocardium
A micrograph and an illustration demonstrate the three layers of the heart; the rectangle on the illustration indicates the region shown in the micrograph. The endocardium, the innermost lining of the heart, contacts the blood. The myocardium is the middle, muscular layer of the heart. The outermost layer of the heart is a serous membrane, the epicardium (visceral pericardium). 10x
Myocardium
A micrograph and an illustration demonstrate the three layers of the heart; the rectangle on the illustration indicates the region shown in the micrograph. The endocardium, the innermost lining of the heart, contacts the blood. The myocardium is the middle, muscular layer of the heart. The outermost layer of the heart is a serous membrane, the epicardium (visceral pericardium). 10x
Epicardium
A micrograph and an illustration demonstrate the three layers of the heart; the rectangle on the illustration indicates the region shown in the micrograph. The endocardium, the innermost lining of the heart, contacts the blood. The myocardium is the middle, muscular layer of the heart. The outermost layer of the heart is a serous membrane, the epicardium (visceral pericardium). 10x
Annulus fibrosus of cardiac skeleton >
The cardiac skeleton is composed primarily of dense CT, providing a framework for the attachment of cardiac muscle fibers and support for heart valves. Components of the cardiac skeleton include annuli fibrosi (annular rings) and the membranous septum. Annular rings surround each valve and continue with the CT core of each valve; the membranous septum forms part of the interventricular septum.
Conducting system >
The conducting system, modified cardiac muscle fibers, coordinates and regulates heartbeat. This system consists of a sinoatrial node (pacemaker), fibers spreading through the atria, AV node located in lower part of the interatrial septum, AV bundle (green arrow) in ventricular septum, and two bundle branches (black arrows) continuing as Purkinje fibers to innervate ventricular myocardium.
