Find joint via selected vertex:
|  | Select the smooth bind joint via current selected vertex. U can use the joint to constrain object.
How to do this : 1.Selected the smooth bound vertex u want to find the joint. 2.Click the icon in your Maya shelves (If U have installed all the MGTools shelves into Maya shelves) or the icon on the constraint tool bar. 3.The corresponding joint will be selected . Use it to constrain other stuffs.