It is not a true skeleton, but it does provide structure and support for the heart, as well as isolating the atria from the ventricles. This allows the AV node and AV bundle to delay the wave of depolarisation such that the atria can contract and assist in ventricular filling before the ventricles themselves depolarise and contract (the AV bundle is the only part of the conduction system that passes from the atria to the ventricles in a normal heart). It also allows the valves (bicuspid, tricuspid, semilunar) to keep open by giving them structural support[WP]

Dense connective tissue that separates the atria from the ventricles and provides physical support for the heart.

http://upload.wikimedia.org/wikipedia/commons/5/50/Gray495.png

skeleton of heart

cardiac fibrous skeleton

fibrous skeleton of heart

heart fibrous skeleton

uberon

trigona fibrosa

trigonum fibrosum dextrum cordis

anulus fibrosus dexter cordis

anulus fibrosus sinister cordis

trigonum fibrosum sinistrum cordis

UBERON:0004292