In the heart's

conduction system The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through ...

, Bachmann's bundle (also called the Bachmann bundle or the interatrial band) is a branch of the anterior internodal tract that resides on the inner wall of the

left atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two ...

. It is a broad band of cardiac muscle that passes from the

right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two a ...

, between the

superior vena cava The superior vena cava (SVC) is the anatomical terms of location#Superior and inferior, superior of the two venae cavae, the great vein, venous trunks that return deoxygenated blood from the circulatory system, systemic circulation to the atrium ...

and the ascending aorta. Bachmann's bundle is, during normal

sinus rhythm A sinus rhythm is any cardiac rhythm in which depolarisation of the cardiac muscle begins at the sinus node. It is characterised by the presence of correctly oriented P waves on the electrocardiogram (ECG). Sinus rhythm is necessary, but not ...

, the preferential path for electrical activation of the left atrium. It is therefore considered to be part of the "atrial conduction system" of the heart.

History

In 1916, Jean George Bachmann conducted canine experiments. He found that clamping the muscular bundle of fibers that connects the atria caused a significant conduction delay.

Structure

Bachman's bundle receives its blood supply from the sinoatrial nodal artery (right, left or both). 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 In anatomy, the coronary sinus () is a collection of veins joined together to form a large vessel that collects blood from the heart muscle ( myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior ven ...

. ''Atrial automaticity foci'' are within the atrial conduction system. The concentration of converging conduction tracts near the coronary sinus results in considerable automaticity activity originating in that area.

Function

The normal cardiac rhythm originates in the

sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approxi ...

, which is located in the right atrium near the superior vena cava. From there, the electrical activation spreads throughout the right atrium. There are at least four locations where the activation can pass to the left atrium. Apart from Bachmann's bundle these are the anterior interatrial septum, posterior interatrial septum, and the

. Because it originates close to the sinoatrial node and consists of long parallel fibers, Bachmann's bundle is, during

, the first of these connections to activate the left atrium.

References

{{DEFAULTSORT:Bachmann's Bundle Cardiac anatomy

History

Structure

Function

See also

References