Bachmann's bundle

Bachmann's bundle is, during normal sinus rhythm, the preferential path for electrical activation of the left atrium.

This electrical impulse is propagated throughout the right atrium, and through Bachmann's bundle to the left atrium, stimulating the myocardium of the atria to contract.

Apart from Bachmann's bundle these are the anterior interatrial septum, posterior interatrial septum, and the coronary sinus.

In the heart's conduction system, Bachmann's bundle, or the interatrial tract, is a branch of the anterior internodal tract that resides on the inner wall of the left atrium.

Because it originates close to the sinoatrial node and consists of long parallel fibers, Bachmann's bundle is, during sinus rhythm, the first of these connections to activate the left atrium.

It seems that it moves in a radial way, but Bachmann's bundle and coronary sinus muscle play a role in conduction between the two atria, which have a nearly simultaneous systole.

Besides Bachmann's bundle, the other three conduction tracts that constitute the atrial conduction system are known as the anterior, middle, and posterior tracts, which run from the sinoatrial node to the atrioventricular node, converging in the region near the coronary sinus.

Wenckebach's bundle is one of the three internodal pathways, the others being the "posterior internodal tract" (Thorel's pathway), and the "anterior internodal tract" (some fibers of which also project to Bachmann's bundle, and then into the left atrium).