Myocardium

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Myocardium

Heart Myocardium
Heart Myocardium (Heart Muscle) and Coronary Artery Diagram. Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist. Licenses

Myocardium

Myocardium is the muscular middle layer of the wall of the

heart

. It is composed of spontaneously contracting cardiac

muscle

fibers which allow the heart to contract. Heart contraction is an autonomic (involuntary) function of the

peripheral nervous system

. The myocardium is surrounded by the

epicardium

(outer layer of the wall of the heart) and the

endocardium

(inner layer of the heart).

Function of the Myocardium

Myocardium stimulates heart contractions to pump blood from the

ventricles

and relaxes the heart to allow the

atria

to receive blood. These contractions produce what is known as a heart beat. The beating of the heart drives the

cardiac cycle

which pumps blood to

cells

and

tissues

of the body.