Does the Catholic Church teach that Jesus' Human Nature was created? I think this is one of the reasons the we can call Mary the Mother of God.  But I'm confused about the exact meaning of Human Nature and Human Soul.  

So my question is mainly this. What was created at the Incarnation?
Human nature entails a human soul. When Christ became man, every aspect of His human nature was created:


  It is to be remembered that, when the Word took Flesh, there was no
  change in the Word; all the change was in the Flesh. At the moment of
  conception, in the womb of the Blessed Mother, through the
  forcefulness of God's activity, not only was the human soul of Christ
  created but the Word assumed the man that was conceived. (The Incarnation, The Catholic Faith)


The soul, as I understand it, is the rational substance that moves the body. See:


http://www.newadvent.org/cathen/09580c.htm
http://www.newadvent.org/summa/1075.htm