Some people say that after the chi reaches the head-top, it returns to the tan-t’ien down the front of the body, in a kind of circulation. I do experience an odd kind of circulation, but the connection between the head-top and the tan-tien is not so direct for me.
Cranial-sacral theory is really near and dear to my heart. The premise there is that changes in the volume of fluid that surrounds the spinal cord and the brain cause flexion and extension of the entire body. The free movement of the sacrum on horizontal, diagonal, and vertical axes inherent in the structure of the joins with the pelvis is critical, as is the movement of the occiput, the sphenoid, the temporals and parietals. At the top of the head in the suture between the parietals is a set of nerves that control the changes in volume of the spinal fluid.
My understanding is that when awareness is allowed a freedom of location with the relaxed movement of breath, some of the phenomena described as the circulation and accumulation of chi may be felt in connection with the sense of location and the movement of breath.
Yuanwu said, “when you arrive at last at towering up like a mile-high wall, you will finally know that there aren’t so many things” ¹; at such a moment, I believe there is a kind of communication from the sacrum to the parietals and the nerves that control the rhythm of the cranial-sacral fluid. It’s like a pair of tin-cans with strings and washers, and the return is in the cranial-sacral rhythm and the way in which it eases the nerve exits along the spine, until the ability to feel is live throughout the body to the surface of the skin. That is why Yuanwu said:
You should realize that on the crown of the heads of the buddhas and enlightened adepts there is a wondrous way of ‘changing the bones’ and transforming your existence. ²
That is why Cheng Man-Ching in Thirteen Chapters said:
“With this method of circulating ch’i, it overflows into the sinews, reaches the bone marrow, fills the diaphragm, and manifests in the skin and hair.” ³
You could say that the chi returns from the head-top to the skin and hair all over the body, and the freedom of the sense of location to move is suddenly like the freedom in falling asleep. Chi “returns” as a clarity of the senses, including the sense of location, which may or may not be at the tan-tien as awareness takes place.
¹ “Zen Letters: Teachings of Yuanwu”, translated by Cleary & Cleary, 1st ed pg 83.
² Ibid pg 61.
³ “Master Cheng’s Thirteen Chapters on T’ai-Chi Ch’uan”, translated by Wile, 1st ed pg 17.