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 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 at ...

. It is a broad band of

cardiac muscle Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle th ...

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 at ...

, 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 vein th ...

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 s ...

, 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 The sinoatrial nodal artery (or sinuatrial nodal artery or sinoatrial artery) is an artery of the heart which supplies the sinoatrial node, the natural pacemaker center of the heart, and arises from the right coronary artery in around 60% of peopl ...

(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 The atrioventricular node or AV 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 lower back section of t ...

, 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 vena ...

. ''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 approxima ...

, 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 The interatrial septum is the wall of tissue that separates the right and left atria of the heart. Structure The interatrial septum is a that lies between the left atrium and right atrium of the human heart. The interatrial septum lies at angl ...

, 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