The Fibrous Skeleton of the Heart

• • the fibrous plate bisects the heart at the level of the atria and the ventricles, so physically separates the muscle mass of the atria and the muscle mass of the ventricles
  • the fibrous skeleton is a collagenous plate made of densely packed collagen fibres
  • it is found encircling the bases/exiting vessels of the pulmonary trunk and the aorta
  • it also embeds the atrioventricular valves (tricuspid valve on right side, bicuspid/Mitral valve on left side)

  A) fibrous skeleton

  
• Functions of cardiac skeleton:

  • reenforces vessel exit points - helps maintain patency and function of the aorta and pulmonary trunk
  • reenforces valves - help provide stability and aid their function
  • forms a non-excitable zone between atria and ventricles - to safeguard the independent electrical and mechanical activity of the 2 "hemispheres" - the atria and ventricles are only electrically connected at one point called the atrioventricular node - allow action potentials from the atria to pass into the ventricles
  • acts as a tendon and orientates muscle fibres
• • atrial muscle fibres originate from the fibrous plate and orientated around the atria in a circular pattern
  • ventricular muscle fibres arise from cartilaginous fibrous skeleton of the heart and pass around in a figure of 8 pattern to form the ventricles - allowing a ringing pattern to occur during depolarisation/contraction of the ventricles, increasing efficiency as a pump