I did touch upon the power of Mudras in my earlier blog; Mudras are essentially the psychic locks through which we try to block / stop dissipation of energy from our body.
It is believed that when we make the Gyan & Chin mudras, we conserve the energy of open nerves in our palms. While, Nasagra Mudra focuses in the center of eyebrow (the agni chakra or the third eye) and channelizes all energy towards our third eye.
There are predominantly three types of Mudras:
Gyan Mudra or the circuit of knowledge
Chin Mudra or the circuit of consciousness
Nasagra Mudra or the nose tip