imgKopf   = new Image();
  imgKopfBg = new Image();
  imgPfeil  = new Image();

  imgKopf.src   = "images/kopf.png";
  imgKopfBg.src = "images/kopf-bg.png";
  imgPfeil.src  = "images/pfeil.png";

  function kopf( name, mode)
  {
    switch( mode)
    {
      case "kopf":
        document.getElementsByName(name)[0].src = imgKopf.src;
        break;

      case "bg":
        document.getElementsByName(name)[0].src = imgKopfBg.src;
        break;

      case "pfeil":
        document.getElementsByName(name)[0].src = imgPfeil.src;
        break;

      default:
        document.getElementsByName(name)[0].src = imgKopfBg.src;
        break;
    }
  }