The moderator band, also called the septomarginal trabecula, is a consistent structure in the morphologic right ventricle and can be helpful as a landmark in situations where the ventricles may be ambiguous (i.e. in some forms of congenital heart disease).

The term "septomarginal" is descriptive since the muscle extends from the interventricular septum to the margin of the right ventricle, contacting/joining the base of the anterior tricuspid papillary muscle.  

The moderator band does not attach to a tricuspid valve, but acts as part of the electrical conduction pathway of the heart -- part of the right bundle branch.