The chakras are centers of energy in the astral body. Six of them are located along the Sushumna; the seventh – the Sahasrara chakra – at the crown of the head. All are depicted with the certain number of petals, corresponding to the number of nadis emanating from them.
Each petals represents a sound vibration produced when the Kundalini energy passes through the chakra. In addition, all the chakras except the sahasrara ahave their own colour, element and bija mantra, and all six correspond in the physical body to the nerve plexuses along the spine.
At the base of sushumna is Muladhara, which corresponds to the sacral plexus; it is here that Kundalini lies dormant. Next is swadhisthana, corresponding to the prostatic plexus.