Which of the following is the middle internodal tract that connects the sinoatrial node to the atrioventricular node?

Appeared in: PGICH Noida NO-2025

Explanation

The heart's electrical impulse from the sinoatrial (SA) node to the atrioventricular (AV) node travels through three specialized internodal tracts within the right atrium.
These tracts are named based on their anatomical position: anterior, middle, and posterior.
The Tract of Wenckebach is the specific anatomical name for the middle internodal pathway.
It courses behind the superior vena cava to connect the SA node to the superior part of the AV node.

Option A: The Tract of Purkinje (Purkinje fibers) are located within the ventricular walls and are responsible for rapid impulse conduction to the ventricles, not for connecting the SA and AV nodes.
Option B: The Tract of Thorel is the posterior internodal tract, not the middle one.
Option C: The Tract of Bachmann is the anterior internodal tract. It also gives off a branch (Bachmann's bundle) that conducts the impulse to the left atrium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the cardiac conduction system as background academic context rather than a clinical decision trigger.
Understanding the specific conduction pathways is crucial for interpreting ECGs and diagnosing the location of heart blocks and other arrhythmias.
Damage to any of these tracts, for instance from ischemia or fibrosis, can cause delays (blocks) in signal transmission from the atria to the ventricles, affecting cardiac output.
The eponym 'Wenckebach' is also associated with Mobitz Type I second-degree AV block, a condition often located at the level of the AV node, which is functionally related to these tracts.

How to Approach the Question

First, identify the key terms in the question: 'middle internodal tract', 'sinoatrial node' (SA node), and 'atrioventricular node' (AV node).
This is a factual recall question about the specific anatomy of the heart's electrical conduction system.
Recall that there are three specialized pathways that conduct the electrical impulse from the SA node to the AV node.
The three tracts are named for their position: anterior, middle, and posterior.
Match the term 'middle' to its corresponding eponym. The middle tract is known as the Tract of Wenckebach.
Evaluate and eliminate the other options based on your anatomical knowledge: Purkinje fibers are in the ventricles, Thorel's tract is posterior, and Bachmann's tract is anterior.

Concept Tested & Keywords

QW5-sFH8pgyxhrZJe9DeDA

E6 Medicine Harrison 22e Part 1 p. 1966-1968

Practise the full PGICH Noida NO-2025

Attempt every question from this paper in a timed mock, then review the full solution for each one.