Ventricular orientation

The ventricular myocytes are arranged in a more complex spatial orientation than the atrial myocytes. They can be divided into two layers:

• superficial; the layers merge with each other and cross in the interventricular septum:
  • fibres attached to the infundibular tendon pass inferiorly and to the right, across the diaphragmatic and sternocostal heart surfaces, to wrap around the apex of the heart. They are continuous with the papillary muscles of the left ventricle.
  • fibres attached to the right atrioventricular annulus sweep around both ventricles in a circular manner before inserting into the posterior papillary muscle of the left ventricle
  • fibres from the left atrioventricular annulus sweep around both ventricles in a circular manner to merge with the papillary muscles of the right ventricle
• deep:
  • three layers
  • circle the ventricle on their own side before crossing the interventricular septum
  • merge with papillary muscles in both chambers
  • the layer most prominent in the right ventricle crosses to the left to join superficial fibres from the atrioventricular ring to form the posterior papillary muscle
  • the layer least prominent in the right ventricle crosses to the left to join superficial fibres from the infundibular tendon to form the septal papillary muscles
  • the third layer is most prominent in the left ventricle where it contributes to the anterior papillary muscle