which part of mind watches the sensation

Four Parts of the Mind 1. Vinnyana or Consciousness – 6 Vinnyanas. These include the consciousness that arises from the Eye, Ear, Tongue, Nose, Mind and Body. 2. Sanya or Perception – Function of this part of the mind is to recognize and evaluate. 3. Vedhana or Sensation – Function is to realize the sensation. 4. Sankhara or Reaction – Function is to react, to give fruit to the sensation. This is the volition of the mind. The 3 types of Sankharas include a) like line drawn on water b) like line drawn on sand on beach c) like line drawn on rock, deep line. My question which part of mind observes 3.Vedana/Sensation in VIPASSANA ? Is it 1.Vinnyana ? And how come one part of **mind**(the first part) is again **mind**?