PRELIMINARY STUDY ON THE ESSENCE OF MAI-DU IN LING SHU

Chen Keqin

(Shanxi Academy of TCM and Pharmacology, Xi'an)

In the chapter of Mai-du (the measure of pulse) of "Ling Shu" (The Canon of the Spiritual Pivot), it was described as follows:

"Six Yang pulses of hand, stretching from hand to head, measure 5 chi (Chinese foot of Han system) each; 6 times 5 makes 3 zhang . Six Yin pulses of hand, stretching from hand to chest, measure 3 chi and 5 cun (Chinese inch) each; 6 times 3 chi 5 cun makes 2 zhang 1 chi. Six Yang pulses of foot, stretching from foot to head, measure 8 chi each; 6 times 8 makes 4 zhang and 8 chi.Six Yin pulses of foot, stretching from foot to chest, measure 6 chi 5 cun each; 6 times 6 chi 5 cun makes 3 zhang and 9 chi. Two Qiao pulses, stretching from foot to eye, measure 7 chi 5 cun each; 2 times 7 chi 5 cun makes 1 zhang 5 chi, Du-Mai and Ren-Mai measure 4 chi 5 cun each; 2 times 4 chi 5 cun makes 9 chi. All of these pulses and meridians measure 16 zhang and 2 chi in all. These arc ihc main meridian passage-ways for Qi (vital energy)".

Under quiet condition, one complete cycle of blood circulation of a healthy human body takes some 20 seconds. "In one respiration (inspiration and expiration) Qi runs 6 cun; in 270 respirations, Qi runs 16 zhang and 2 chi, completing one cycle round the body" as stated in "Ling Shu". This complete cycle of Qi circulation takes 15 minutes. It is 45 times as much as that of blood circulation. Obviously, "In one respiration, Qi runs 6 cun" does not stand for the velocity of blood circulation. But does it stand for the conducting velocity of nerve fibres. It is known that the conducting velocity of human motor nerve ranges from 60 to 120 meters per second. Evidently, it does not stand for the conducting velocity of nerve fibres, too. Nevertheless, it somewhat corresponds to the velocity of propagating sensation along meridians (PSM) in acupuncture which ranges from several centimeters to more than ten centimeters per second.

According to Han system, one chi is equal to 27.63 centimeters. In one respiration, Qi runs 6 cun which is equal to 16.578 centimeters. For Qi to travel the entire cycle of pulses and meridians (16 zhang and 2 chi), there should be 270 respirations. Supposing there are 18 respirations in one minute, each respiration takes 3.3 seconds. Hence, the velocity of Qi is equal to 5.023 centimeters per second. Therefore, it may be regarded that the measure of pulses in "Ling Shu" was recorded according to the lengths of meridians determined by propagating sensation along meridians.