The Circulation of the Light

The microcosmic orbit
The ch'i is guided up the back, and then is brought down the front of the body, completeing the circuit
sketch from Mantak and Maneewan Chia Awaken Healing Light of the Tao (Healing Tao Books, 1993), p.425.

Instead of a simple ascent of the life-force along the spine to the top of the head, as in Indian Tantra, the Taoist practitioners of "Internal Alchemy" (Nei-Tan) refer to a continual circulation of the ch'i (vitality principle) up the primary yang (positive), back or Governor Channel (tu mai or du mo) and down the primary yin (negative), front or Functional Channel (jen mai or ren mo) of the body. This is called "The Circulation of the Light," or "The Lesser Heavenly Cycle" (as opposed to the greater cycle of the rotation of stars and constellations) or "Microcosmic Orbit".

However, Ferran Blasco Aguasca has pointed out to me (in an email) that the circulation along the Microcosmic Orbit and the circulation in the center running back and forth from perineum to crown are two different things. There are practices in Chinese Alchemy that emphasize working with the chong channel, the thursting or central channel, which seem to be more similar to what the Indian Tantrics refer to in kundalini yoga.
http://www.kheper.net/topics/Taoism/Nei_Tan_intro.html