सुषुम्णा, suṣumṇā

ray of sunshine, the most gracious channel

Sushumna is an energy channel located along the spine from muladhara to sahasrara, through which rises Kundalini.

Inside it, like matryoshkas nested inside one another, three more subtle channels vibrate through vajra-nadi ("shining like the Sun"), the chittrini-nadi, and the even more subtle "shining with the unearthly sparkle" brahma-nadi, by which the power of the Kundalini, when awakening, rises up to the sahasrara chakra.

The nadis that are inside sushumna are associated with the regulation of the forces of the three gunas.

Sushumna is enlaced by ida and pingala — two important channels that are responsible for the operation of two currents, the lunar and the solar. From the ida, pingala and sushumna all other channels emanate. In India, they are called streams (nadis) and are symbolically identified with the local sacred rivers.

It is impossible to perceive sushumna with ordinary material feelings and mind since the mind dissolves in it and as a result, the empirical consciousness is completely transformed.