夫寸关尺位。多有不同。然脉法始于黄帝。难经起自扁鹊。此之二部。俱是祖宗。诸家
所述。盖并枝叶。今则分其尺寸。定其阴阳。的举指归。用明大要。俾令后学。免更狐疑。
经曰∶凡寸关尺者。脉之要会也。从关至尺。是尺内。阴之所治也。从关至鱼际。是寸口内。
阳之所治也。故分寸为尺。分尺为寸。阴得尺内一寸。阳得寸内九分。尺寸终始。一寸九分
也。夫人之三部。寸口在上。关脉在中。尺脉在下。经云∶先言尺。后言寸。不从上而言。
反从下起者。缘尺泽是人性命之根本。寸口者人身之本。故有命然后有身。所以先言尺泽在
上。盖取命之根本。然后及于身而言之也。凡十二经脉。有病之时。先于尺泽寸口而见之。
故尺寸者。是脉之要会也。从关至尺。是尺内阴之所治者。夫三部之脉取中。而上下分之。
从关中下至尺泽为内。是属阴。故言内阴之所治也。言尺泽者。尺脉一寸之外。余脉下入不
见。如入深泽而沉。故曰尺泽也。凡诊之者。若寸口关脉不见。唯尺脉在者。其人必不死。
亦如树之有根。枝叶虽枯。其根气元活。故寸关者枝叶也。尺泽者根本也。从关至鱼际是寸
口内。阳之所治者。夫自关而向上分之。上至寸口。故言关至鱼际也。鱼际者是掌骨后际。
如鱼之颈际。故曰鱼际也。言从关上至鱼际。下占一寸属阳。是内阳之所治也。然寸口虽占
一寸。而脉见九分者。言阳数奇。阴数偶故也。是以关上属阳。故言九奇也。关下属阴。故
言寸偶也。故分寸为尺者。夫关以上。虽取一寸。而脉见九分。故曰分寸。为其先取一尺而
言。盖先从根本言之。故一尺内取一寸。一寸内取九分而诊之。故言分寸为尺。从尺而取寸。
从寸而取分是也。分尺作寸者。从关以下至尺泽也。盖取脉长一寸而诊之。其一寸之脉。盖
先取一尺之分。而其中除却九寸。而更取一寸用之。故言阴得尺内一寸。阳得寸内九分。从
始至终。寸尺位脉长一寸九分。此则尺寸始终之法也。凡寸后尺前。两境之内生于关。为寸
关尺也。上部属阳故法天。下部属阴故法地。中部阴阳相共。故法人。关者穿也。言上可以
穿其天。下可以穿其地。上下关通。而取其中。故言关也。而分三部候天地人。以法三才也。
凡古法定尺寸者。皆先取一尺而言之。从尺而取寸。此则是其大纲也。又凡人长短不同。其
形各异。又曰人长则脉长。人短则脉短。据此之言。岂可执其一概。必在医者以意审详。今
则以鱼际骨下为寸口。位占九分。更下行一寸为尺部。合成一寸九分。中间为关部。以安三
指
不欲备载。深为冗繁。故不可以依凭尔。
The positions of Cun (Inch), Guan (Bar), and Chi (Cubit) vary among different physicians. However, pulse diagnosis originated from the Yellow Emperor, and the *Nan Jing* (Classic of Difficult Issues) began with Bian Que. These two works are the ancestors of all schools; descriptions by later authors are merely branches derived from these roots. Now, we delineate the positions of Cun and Chi, define their Yin and Yang attributes, clarify the finger placement for palpation, and elucidate the main principles, thereby enabling students to avoid confusion.
The Classics state: "Cun, Guan, and Chi are the crucial convergence points of the pulse." From Guan to Chi is called "Chi Nei" (Inner Chi), which is governed by Yin Qi. From Guan to Yu Ji (Fish Border) is called "Cun Kou Nei" (Inner Cun Kou), which is governed by Yang Qi. Therefore, Cun is divided into Chi, and Chi into Cun. Yin occupies one cun within Chi, while Yang occupies nine fen within Cun. The total length from the beginning to the end of Cun and Chi is one cun and nine fen.
In the human body, the three pulse positions are arranged as follows: Cun Kou is superior, Guan is middle, and Chi is inferior. The Classics say: "Chi is mentioned before Cun," not proceeding from top to bottom, but rather starting from the bottom upwards. This is because Chi Ze (referring to the depth of the Chi pulse) is the root of life, while Cun Kou is the root of the physical body. Since life precedes form, Chi Ze is mentioned first as representing the root of life, followed by the discussion of the body. When the twelve meridians are diseased, manifestations appear first at Chi Ze and Cun Kou. Thus, Cun and Chi are the crucial convergence points of the pulse.
From Guan to Chi is where Yin Qi governs the inner region. The three pulse positions are taken at the center and differentiated above and below. From Guan downwards to Chi Ze constitutes the interior, belonging to Yin; hence it is said to be "governed by internal Yin." The term "Chi Ze" refers to the fact that beyond one cun of the Chi pulse, the remaining pulse sinks deep and becomes invisible, like sinking into a deep pool; thus it is named Chi Ze. In pulse diagnosis, if Cun Kou and Guan pulses are imperceptible, but only the Chi pulse is present, the patient will certainly not die. This is analogous to a tree: even if the branches and leaves wither, the root qi remains alive. Therefore, Cun and Guan represent the branches, while Chi Ze represents the root.
From Guan to Yu Ji is the interior of Cun Kou, governed by Yang Qi. Differentiating upwards from Guan to Cun Kou is referred to as "Guan to Yu Ji." Yu Ji is the posterior edge of the metacarpal bone, resembling the neck border of a fish, hence the name. It is stated that from Guan upwards to Yu Ji, the lower portion occupying one cun belongs to Yang, governing internal Yang. Although Cun Kou occupies one cun, the pulse manifests over nine fen because Yang numbers are odd and Yin numbers are even. Therefore, the area above Guan belongs to Yang, hence "nine odds"; the area below Guan belongs to Yin, hence "one even."
The phrase "dividing Cun to form Chi" implies that although one cun is measured above Guan, the pulse manifests only nine fen. It is called "dividing Cun" because it originates from the concept of measuring one Chi first, emphasizing the root initially. Thus, within one Chi, one Cun is taken; within one Cun, nine fen are taken for diagnosis. Hence, "dividing Cun forms Chi." Taking Cun from Chi, and Fen from Cun, is what is meant by "dividing Chi to form Cun." From Guan downwards to Chi Ze involves measuring a pulse length of one cun. This one cun of pulse is derived by taking the division within one Chi, excluding nine parts, and utilizing one part. Thus, "Yin obtains one cun within Chi, and Yang obtains nine fen within Cun." From start to finish, the combined length of Cun and Chi positions is one cun and nine fen. This is the method of the beginning and end of Cun and Chi.
Between the position after Cun and before Chi lies Guan, forming the triad of Cun, Guan, and Chi. The upper part belongs to Yang and models Heaven; the lower part belongs to Yin and models Earth; the middle part contains both Yin and Yang and models Humanity. "Guan" means to penetrate; it signifies penetrating Heaven above and Earth below, connecting upper and lower through the center, hence named Guan. The three positions are used to inspect Heaven, Earth, and Humanity, modeling the Three Powers (San Cai).
Ancient methods for defining Cun and Chi always started by referencing one Chi, deriving Cun from Chi; this is the general principle. Furthermore, people differ in height and physique. It is said that tall people have long pulses, and short people have short pulses. Based on this, how can one adhere rigidly to a single standard? Physicians must carefully examine each case individually. Currently, we define the position below the bone of Yu Ji as Cun Kou, occupying nine fen; moving down one cun defines the Chi section, totaling one cun and nine fen; the middle section is Guan, accommodating three fingers.
We do not record everything in detail because it would be overly cumbersome and complex, and thus should not be relied upon exclusively.