bundle of his(n = noun.body) atrioventricular bundle, atrioventricular trunk, truncus atrioventricularis - a bundle of modified heart muscle that transmits the cardiac impulse from the atrioventricular node to the ventricles causing them to contract;
is a kind of cardiac muscle, heart muscle

atrioventricular bundle, bundle, bundle off, bundle up, fiber bundle, fibre bundle, fibrovascular bundle, his, in his own right, in his right mind, off his guard, up to his neck, vascular bundle