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size of a fist
In the mediastinum between second rib and fifth intercostal space
On the superior surface of diaphragm
Two-thirds to the left of the midsternal line
Anterior to the vertebral column, posterior to the sternum
Enclosed in pericardium, a double-walled sac
Deep two-layered serous pericardium
Parietal layer lines the internal surface of the fibrous pericardium
Visceral layer (epicardium) on external surface of the heart
Separated by fluid-filled pericardial cavity (decreases friction)
Spiral bundles of cardiac muscle cells
Fibrous skeleton of the heart: crisscrossing, interlacing layer of connective tissue
Anchors cardiac muscle fibers
•Supports great vessels and valves
•Limits spread of action potentials to specific paths
Separated internally by the interatrial septum
Coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles
Auricles increase atrial volume
Separated by the interventricular septum
Anterior and posterior interventricular sulci mark the position of the septum externally
Atria: The Receiving Chambers
Walls are ridged by pectinate muscles
Vessels entering right atrium
Superior vena cava
Inferior vena cava
Vessels entering left atrium
Right and left pulmonary veins
Ventricles: The Discharging Chambers
Walls are ridged by trabeculae carneae
Papillary muscles project into the ventricular cavities
The functional blood supply to the heart muscle itself
Arterial supply varies considerably and contains many anastomoses (junctions) among branches
Collateral routes provide additional routes for blood delivery
Coronary Circulation: Arteries
Right and left coronary (in atrioventricular groove), marginal, circumflex, and anterior interventricular arteries
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