NĀḌĪ
(Sanskrit: नाडी, lit. 'tube, pipe, nerve, blood vessel, pulse') Channels through which, in traditional Indian medicine and spiritual knowledge, the energies such as prana of the physical body, the subtle body and the causal body are said to flow. Within this philosophical framework, the nadis are said to connect at special points of intensity, the chakras. The three principal nadis are the ida on the left, the sushumna in the centre, and the pingala on the right; they run from the base of the spine to the head.
PURPOSE
The purpose of yoga is moksha, liberation and hence immortality in the state of samadhi. This is obstructed by blockages in the nadis, which allow the vital air, prana, to languish in the Ida and Pingala channels. The unblocking of the channels is therefore a vital function of yoga. The various practices of yoga, including the preliminary purifications or satkarmas, the yogic seals or mudras, visualisation, breath restraint or pranayama, and the repetition of mantras work together to force the prana to move from the Ida and Pingala into the central Sushumna channel. The mudras in particular close off various openings, thus trapping prana and directing it towards the Sushumna. This allows kundalini to rise up the Sushumna channel, leading to liberation.