MUDRAS
As with Mantras, there is more to the actions than mere rites and ceremony. The problem is that they have been abused and few understand their value and significance. They can be extensive, as they are with Tibetan Lamaism, or quite simple as they are in Theravada Buddhism. In both cases, the understanding is minimal today and this is unfortunate, because when they are used correctly they are a strong tool for the path.
This is a figurative representation of the body map encoded in the cortex. You are probably familiar with this drawing, which you may now intuit is important for Mudras. It shows that body parts with complex repertories of fine movements, like the hand, require more cortical space in M1, while body parts with relatively simpler movements require less cortical space.
Likewise you can see that the Sensory cortex has a similar distribution.
You can see then that, as far as the construction phase of the Mudra is concerned, there is a fantastic repetoire with great subtlety available which is essencially non verbal. This is accompanied clearly with verbal information which is stored in memory accompanied by sub-vocalization, which occurs in all conscious thinking. The movements in constructing a Mudra then which is finely tuned to specific expressions is received by the sensory cortex. It is received as you can see by the sensitive hands which transmit that signal to the central nervous system, together with the cognitive understanding of the signal.
With the Mudras then you are actually talking to yourself with hand-sign language and, like any repetition, the meanings are reinforced.
The question is, why not just do the same thing vocally?
Look at the sensory cortex. Find the ear? Nowhere. Look at the Motor cortex. Where is the ear? The ears are on the face, small and almost non- existent. Let us now return to the sensory cortex. The tongue, the nose, and the eyes are there and what is very clear is that the sensory organ of tact, that same hand, is with strong cortical connections.
Thus with Mudras we have a perfect situation in which the hands are virtually talking to themselves supported by the organ of speech, the tongue.
Now Mudras are not performed in a state of normal consciousness but in states of higher consciousness if not trance or meditation, therefore the repetition operation of Mudras is un-tainted by cognitive thought if the significance has been originally presented without any interference of the mind.
It is hoped that this takes the mystery out of Mudras incorrectly understood and used that actually inhibit their function and closes the door to superstitious comportment and frivolous ideas of cosmic consciousness.