Corpus: Internodal tract
from Latin: inter - between, nodus - node
1. Definition
The term internodal tract refers to three fibre bundles of the atrial myocardium that run from the sinus node to the atrioventricular node (AV node).
2. Background
The existence of internodal bundles has been debated for several decades, as their course cannot be distinguished histologically, and the cardiomyocytes within these supposed bundles do not differ significantly from the surrounding atrial myocardium. Recent literature (2021) suggests that internodal bundles may not actually exist in the human atrium.[1]
3. Classification
Three internodal bundles are traditionally distinguished:
- Anterior internodal tract (Bachmann-James bundle)
- Middle internodal tract (Wenckebach bundle)
- Posterior internodal tract (Thorel bundle)
Additionally, the interatrial bundle (Bachmann's bundle) branches off from the anterior internodal tract and runs to the left atrium.
4. Function
The internodal bundles are proposed to be part of the heart's conduction system, conducting electrical impulses from the sinus node across the right atrial wall to the AV node.
5. Sources
- ↑ Eduardo Back Sternick, Damián Sánchez-Quintana: Critical Assessment of the Concepts and Misconceptions of the Cardiac Conduction System over the Last 100 Years: The Personal Quest of Robert H. Anderson. Journal of Cardiovascular Development and Disease, January 2021