Scars left by the muscles which close the bivalve shell, normally one or two are present; exceptionally, as in species of the family Pholadidae, a third accessory adductor scar may be present where the pallial line is expanded as it bends back into the pallial sinus (=vental adductor scar).

Alternative forms for adductor muscle scars : adductor muscle scar, adductor scar, adductor scars.