In the heart's conduction system, 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. It is a broad band of cardiac muscle that passes from the

right atrium The atrium (; : atria) is one of the 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 mitral and tricuspid heart valves. ...

, between the

superior vena cava The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vei ...

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

Bachmann'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 Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

, middle, and posterior tracts, which run from the sinoatrial node to the

atrioventricular node The atrioventricular node (AV node, or Aschoff-Tawara node) electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the ...

, converging in the region near the

coronary sinus The coronary sinus () is the largest vein of the heart. It drains over half of the deoxygenated blood from the heart muscle into the right atrium. It begins on the backside of the heart, in between the left atrium, and left ventricle; it begi ...

. ''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, sinus node or Keith–Flack node) is an ellipse, oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of Cell (biology), cells known as pa ...

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

References

{{DEFAULTSORT:Bachmann's Bundle Cardiac anatomy

History

Structure

Function

See also

References