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Laboratory 20. Heart
Step 17. The Sinoatrial (SA) Node and the Atrioventricular (AV) Node

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Identify the location of the sinoatrial (SA) node and atrioventricular (AV) node (Figure 20.6). Both nodes consist of specialized cardiac muscle fibers known as Purkinje fibers. The sinoatrial node is the site where the impulses for contraction are generated, it is the "pacemaker" of the heart. The atrioventricular node recieves impulses that travel in internodal tracts located in the walls of the right atrium. the AV node is continuous with the atrioventricular bundle. Although they cannot be easily seen in a cadaveric specimen, these nodes are extremely important clinically. It is important to have a basic knowledge of their location and blood supply.

The sinoatrial (SA) node can be found in the superior part of the crista terminalis near the ostium of the superior vena cava.

The atrioventricular (AV) node lies in the lower part of the interatrial septum, near the ostium of the coronary sinus .

Links and References:
Grant's: 1.69
Rohen/Yokochi: 243