Expansion
Four fibrous rings that anchor the valves, attach the myocardium and insulate atria from ventricles
Expansion
Four fibrous rings surround the valve orifices and fuse into a single skeleton. It has four jobs:
- Anchors the four valve annuli and keeps the orifices from dilating
- Attaches atrial and ventricular myocardium
- Insulates the atria electrically from the ventricles
- Supports the membranous interventricular septum
The insulation point is the one to hold onto. The only normal electrical connection across it is the bundle of His, which is why the atrioventricular node can control ventricular rate and why accessory pathways such as the bundle of Kent, an abnormal muscular bridge across the skeleton, cause Wolff-Parkinson-White syndrome.