adjective
referring to the atria and ventricles
atrioventricular bundle or AV bundle or bundle of His = bundle of modified cardiac muscle which conducts impulses from the atrioventricular node to the septum and then divides to connect with the ventricles
atrioventricular groove = groove round the outside of the heart, showing the division between the atria and ventricles
atrioventricular node or AV node = mass of conducting tissue in the right atrium, which continues as the bundle of His and passes impulses from the atria to the ventricles