Different organs of our body are governed by different devas. The solar plexus is connected with the sun, that's why it is called "solar" plexus. When the first rays of the sun fall on the solar plexus, it is very good for your body. Doing Surya Namaskar ("sun salutation") yoga asana in the early morning is very good. The solar plexus has a profound impact on the central nervous system, optic nerves, stomach, and what we usually call "gut feeling." It is the second brain in your body. Usually the solar plexus is slightly bigger than an almond. Studies have shown that with the practice of yoga, meditation, and Sudarshan Kriya, the solar plexus can become as a large as the size of the palm. Then it performs better. It balances the body functions. When the solar plexus expands, the intuitive mind works better. The mind becomes clear and focussed. When the solar plexus contracts, one feels horrible, sad, depressed, and all the negative feelings come.
Krishna was called Padmanabha, meaning "whose navel is the size of a lotus flower." If you become Padmanabha, you become absolutely creative. Brahma, the Creator, is born out of a blossomed solar plexus.
These days, the solar plexus remains small, but the tummy keeps getting bigger.