Index finger and thumb are connected together in such a way that the index finger touches the base of the thumb and the three fingers are stretched outward and the hands placed on the knees palms facing downward.

The hands left and right have different effects in the hand mudras. The left-hand generates more of the instinctive internal energy with effects coming from the space. The right hand initiates the energies from lower chakras and kundalini.
The placement of hands and fingers play a significant role. A meditator should know the effects of placement of hands and fingers and should understand what happens when you are following certain yogic or meditation processes.

The fingers have a relationship with the five natural elements and stimulate these aspects in the personality and higher consciousness:
Thumb – fire
Index finger – air
Middle finger – ether
Ring finger – earth
Little finger – water