The myocardium consists of thick bundles of cardiac muscle twisted and whirled into ringlike arrangements and it is the layer that actually contracts. The epicardium or the visceral and outermost layer is actually a part of the heart wall. The heart muscle has three layers and they are as follows: Deep to the fibrous pericardium is the slippery, two-layer serous pericardium, where its parietal layer lines the interior of the fibrous pericardium. The loosely fitting superficial part of this sac is referred to as the fibrous pericardium, which helps protect the heart and anchors it to surrounding structures such as the diaphragm and sternum. The heart is enclosed in a double-walled sac called the pericardium and is the outermost layer of the heart. Its broad posterosuperior aspect, or base, from which the great vessels of the body emerge, points toward the right shoulder and lies beneath the second rib. ItвЂ™s more pointed apex is directed toward the left hip and rests on the diaphragm, approximately at the level of the fifth intercostal space. Snugly enclosed within the inferior mediastinum, the medial cavity of the thorax, the heart is flanked on each side by the lungs. Approximately the size of a personвЂ™s fist, the hollow, cone-shaped heart weighs less than a pound. The modest size and weight of the heart give few hints of its incredible strength. The cardiovascular system can be compared to a muscular pump equipped with one-way valves and a system of large and small plumbing tubes within which the blood travels. The heart separates the pulmonary and systemic circulations, which ensures the flow of oxygenated blood to tissues. The valves of the heart secure a one-way blood flow through the heart and blood vessels. Contractions of the heart produce blood pressure, which is needed for blood flow through the blood vessels. Variations in the rate and force of heart contraction match blood flow to the changing metabolic needs of the tissues during rest, exercise, and changes in body position. The functions of the heart are as follows: Capillary Exchange of Gases and Nutrients.Intrinsic Conduction System of the Heart.Major Veins of the Systemic Circulation.Major Arteries of the Systemic Circulation.Therapeutic Communication Techniques Quiz.

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