Cardiovascular: Physiology - Cardiac excitation

Question 1

List the structures making up the cardiac conduction system

Answer 1

1. Sinoatrial node
2. Internodal atrial pathways
   a. Anterior
   b. Middle (tract of Wenckebach)
   c. Posterior (tract of Thorel)
3. Atrioventricular node
4. Bundle of His
   a. Left bundle branch
   i. Anterior fascicle
   ii. Posterior fascicle
   b. Right bundle branch
5. Purkinje fibres

Question 2

Where is the SA node located?

Answer 2

At junction of SVC with RA

Question 3

How does conduction occur between the SA and AV nodes?

Answer 3

Via internodal atrial pathways (anterior, middle, posterior bundles)
Atrial myocytes (slower)

Question 4

Where is the AV node located?

Answer 4

Right posterior portion of interatrial septum