The sakti (energy) goes through nadis (channels) from the muladhara to the sahasrar. The Nadis are subtle and not part of a physical element. What is the purpose of the Kundalini? It is indeed for the sadhak to attain samadhi. The potentiality is compressed in the Kunda (pot). As the potentiality releases into actuality various forms that emanate are associated with Lakshmi//Durga//Saraswathi//Devi.. What is the amrita that Dhanvantri carried that was sought by the Devas and Asuras? It is nothing but the amrit (immortal nectar) that flows and releases through the subtle when the union of Siva with Sakti is attained in the Sahasrar. This drip flows into the nadis and a certain tandava nritya nada of Shiva is attained giving the bliss of LaxmiNarayan. KUNDALINI is KUNDA+LINI. What does this mean? Kunda is the cavity. Lin is the coil. This is the potential power of the coiled serpent. At the grantha (the base of the spine) the sushmna nadi originates and goes all the way in the subtle (sookshma or ethereal) plane and shows the head above the sahasrar like a seprent. When the kundalini releases from the spring at the base the fiery red eyes of the snake sprout up heating each chakra as it goes up and cooling the one it leaves until it emerges as the head of the snake at the sahasrar where shiva is mithunam (content) with parvati-maa (sakti) These lightning flashes of the rousing kundalini going up the sushmna can be controlled through sadhana (continued-spiritual-practice). Ida is the feminine nadi ruled by chandra , pingala is the male nadi ruled by surya and sushmna is the brahma+agni. Starting from the base and to the top where they meet again is where rivers become rivers again and oceans become oceans. This is triveni of Yamuna (chandra), Saraswati (surya) and Ganga (agni). Snaana in the triveni or prayaaga is contentment due to paapa-naasha in the Ajna.
OM Tat Sat