Expansion
Anterior, posterior and septal papillary muscles, with the moderator band to the anterior muscle
Expansion
The right ventricle contains three papillary muscles, matching the three tricuspid cusps:
- Anterior - the largest, receiving the moderator band
- Posterior
- Septal - small and variable, arising from the interventricular septum
The moderator band (septomarginal trabecula) runs from the interventricular septum to the anterior papillary muscle. It carries the right bundle branch, so it ensures the papillary muscle contracts early and tightens the chordae before ventricular systole develops full pressure.
By contrast, the left ventricle has only two papillary muscles, anterolateral and posteromedial, for the two mitral cusps.