cardiac papillary muscle physiology

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blaze626's picture
cardiac papillary muscle physiology

I am studying cardiac A&P at the moment, and my text, instructor, and web search isn't clarifying the action of the papillary muscle in the ventricles of the heart.

Here is what I think I understand about this system:

The leaflets of the av valve are attached to chordeae tendineae that are attached to papillary muscles that are attached to the wall of the ventricle. Therefore, they must be loose inside the ventricle when the av valve is open. When the av valve closes, it is kept from swinging into the atrium by the chordeae tendineae. So, are the papillary muscles there to pull the av valve open after ventricular contraction? Why doesnt the av valve just open passively at this point? And if it does, what would be the point of the papillary muscles?

Thank you to anyone who can help...

Guy Sovak
Guy Sovak's picture
The papillary muscle, start

The papillary muscle, start contracting before the contraction of the ventricle due to that the cordae tendineae are tightening and thus drawing the cusps together. The papillary muscles are attached to adjacent sides of two cusps and thus keep the cusps tight preventing their separation. Also preventing a possible inversion of the cusps while being in systole.
Hope this clarify even more your understanding.