What is the correct order of the cardiac conduction pathway from the SA node to the Purkinje fibers?

• A. SA Node - Internodal Pathways - AV Node - Bundle of His - Bundle Branches - Purkinje Fibers
• B. SA Node - AV Node - Internodal Pathways - Bundle of His - Bundle Branches - Purkinje Fibers
• C. SA Node - Internodal Pathways - AV Node - Purkinje Fibers - Bundle of His - Bundle Branches
• D. SA Node - AV Node - Bundle of His - Internodal Pathways - Bundle Branches - Purkinje Fibers

Answer: (A)

Understanding the order of electrical conduction and why the AV node delays the signal is essential. The impulse starts in the SA node and quickly spreads through the atrial tissue via the internodal pathways, delivering the signal to the AV node. The AV node then provides a brief delay to allow the atria to contract and complete ventricular filling. From the AV node, the impulse travels down the Bundle of His, then moves through the right and left bundle branches, and finally through the Purkinje fibers to activate the ventricles rapidly and in a coordinated way. This sequence—SA node to internodal pathways to AV node, then His, bundle branches, and Purkinje fibers—matches the heart’s anatomy and ensures proper timing of atrial and ventricular contractions.