This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Impulses from SA node to the left atrium and AV node passes through: 
Select and explain. 
A. Bundle of His, B. Bachmann bundle, C. Purkinje fibres, D. None
B: Bachmann bundle
Answer: B: Bachmann bundle 
Explanation: There are three bundles of atrial fibers that contain Purkinje-type fibers and connect the SA node to the AV node: the anterior, middle (tract of Wenckebach), and posterior (tract of Thorel) tracts.
Bachmann bundle is sometimes used to identify a branch of the anterior internodal tract that connects the right and left atria. 
 
Key Concept
3 INTERNODAL TRACTS:
Connects SA node to AV node:

Anterior – Bachman’s bundle
Middle – Wenckebach’s bundle
Posterior – Thorel’s bundle

Reference: Ganong’s Review of Medical Physiology T W E N T Y - F I F T H   E D I T I O N page no 519