人身阴阳元气。皆起于下。故内经以广明之后。即为太冲。太冲之地。属之少阴。少阴之前。乃为厥阴。其部为血
海。常与太冲腾精气。而上灌渗阴阳。斯则人之元气精气。皆起于下也。而由下而起。则分三道而上。其阳者。从少阴
之后。行太阳夹脊之中道。以总统诸阳。其名为督。其阴者。由前阴地道。而上行阳明之表中。以总统诸阴。其名为任。
而中央一道。则脉起血海。腾精气而上积于胸中。为宗气以司呼吸。其名为冲。是气则与阳明胃气俱住中州。亦与营俱
行十二经者也。盖尝考之督脉起胞中。上巅历百会神庭。任脉起中极之下胞中。循关元历承浆。上与督脉会。冲脉起胞
中。上行伏脐。会于咽喉。三脉同起于下极。一源而三歧。故圣人不曰冲督任。而总名曰太冲。是太冲者、以一身之精
气上升言之。不独为血海言之也。中外之间。横者为带脉。带脉横于季胁。统于章门五枢。总束诸脉。使上下有常。而
要约营束之。毋令懒散。其脉如人束带而前垂。亦精气关锁也。此处为膂。人之全力出焉。膂力不衰。殆为此也。二维
者。维持维系之义。人身阳脉统于督。阴脉统于任矣。而诸阳诸阴之散见而会。又有所必维系而持之。故有阴维以维于
诸阴。阳维以维于诸阳。然而能为维者。必从阴阳之根柢。具盛气之发。而后能维。阳维从少阴至太阳。发足太阳之金
门。而与手足少阳阳明。五脉会于阳白。阴维从少阴斜至厥阴。发足少阴之筑宾。至顶前而终。少阴少阳。为阴阳根柢
之气。维于阳者。必从少阴以起之。是阴为阳根也。维于阴者。必从少阳而起之。是阳为阴致也。故二脉又为营气之纲
领焉。两跷脉者。跷以矫举为义。其脉之剽悍同于卫气。而皆上于目。然有孔道与卫不同。其脉则阴出阳而交于足太阳。
阳入阴而交于足少阴。其气其行。每从阴阳根柢和合。以为矫举而上荣。大会于目。故目之瞑开皆宜。其曰阴脉荣其脏。
阳脉荣其腑者。入阴则荣脏。入阳则荣腑也。男女脉当其数者。男子阳用事。其跷在阳。故男子数断其阳。女子阴用事。
其跷在阴。故女子数断其阴。总之八脉唯带脉横束手膂。而七脉皆自下柱而上。虽有孔道宗众会。然当起于太阳少阴。
则皆所谓太冲之义也。故圣人止言太冲。而不及督任维跷。盖有分之而不分者矣。
人身中的阴阳元气，都起源于下部。所以《内经》在论述“广明”之后，紧接着就提到了“太冲”。太冲之地，归属于少阴经。少阴经的前方，便是厥阴经，其部位被称为血海，经常与太冲一起腾涌精气，向上灌溉并渗透至阴阳各部。这样看来，人的元气和精气，都是从下部产生的。而这些从下部升起的精气，分为三条道路向上运行：其中属阳的，从少阴经的后方，沿着夹脊的中道行走于太阳经，以统领所有的阳经，这条脉称为督脉；属阴的，从前阴的地道向上，进入阳明经的表里之间，以统领所有的阴经，这条脉称为任脉；而中间的一条道路，则脉起于血海，腾涌精气向上积聚于胸中，形成宗气来主持呼吸，这条脉称为冲脉。这股气与阳明胃气共同驻留于中焦（中州），也伴随营气运行于十二经脉之中。
我曾经考证过，督脉起于胞中，上行至头顶，经过百会穴、神庭穴；任脉起于中极穴下方的胞中，循行经过关元穴，历经承浆穴，向上与督脉相会；冲脉起于胞中，上行伏于脐旁，会合于咽喉。这三条脉同起于下极（会阴部），同源而分出三支，所以圣人不说冲、督、任，而是总称为“太冲”。所谓“太冲”，是从一身精气上升的角度而言的，不仅仅指血海这一概念。
在中外之间，横向的是带脉。带脉横行于季胁部位，统属于章门穴和五枢穴，总束所有的经脉，使上下保持常态，约束营气，不让其懒散松懈。它的形状就像人系着腰带前面下垂的样子，也是精气关锁的地方。这个部位叫做“膂”，人体的全力由此发出，膂力不衰，大概就是因为这个原因。
“维”字，有维持、维系的意思。人身上的阳脉由督脉统领，阴脉由任脉统领了，但是诸阳诸阴分散显现又汇聚之处，又有必须维系和支撑它们的脉络。所以有阴维脉来维系诸阴经，阳维脉来维系诸阳经。然而，能够起到维系作用的脉，必然要从阴阳的根本出发，具备旺盛之气的发动，然后才能维系。阳维脉从少阴经走向太阳经，发源于足太阳经的金门穴，并与手少阳、足少阳、手阳明、足阳明这五条脉会合于阳白穴；阴维脉从少阴经斜向走到厥阴经，发源于足少阴经的筑宾穴，到达头顶前方结束。少阴经和少阳经，是阴阳根本之气。维系阳气的，必然从少阴经发起，这说明阴是阳的根本；维系阴气的，必然从少阳经发起，这说明阳是阴的引导。所以这两条脉又是营气的纲领。
两跷脉（阴跷、阳跷），“跷”字意为矫健举步。它们的脉气剽悍滑利，类似于卫气，都上行至眼部，但是孔道与卫气不同。阴跷脉出于阳分而交于足太阳经，阳跷脉入于阴分而交于足少阴经。它们的气机和运行，往往从阴阳根本的和合中产生，用来矫健举步而上荣养头部，大会于目，所以眼睛的开合都很适宜。所说的“阴脉荣养其脏，阳脉荣养其腑”，是指进入阴分就荣养脏，进入阳分就荣养腑。
男女的脉数在其功能表现上有所不同：男子阳气用事，其跷脉侧重于阳，所以男子的脉象多断绝于阳分（或理解为阳气主导）；女子阴气用事，其跷脉侧重于阴，所以女子的脉象多断绝于阴分（或理解为阴气主导）。总之，八脉中只有带脉横向束缚于腰脊，而其余七脉都是从下部柱立而上行。虽然有各自的孔道和众多的会合点，但既然都起于太阳、少阴，那就都是所谓“太冲”的含义。所以圣人只说太冲，而不单独提及督、任、维、跷，这是因为既有区分又不完全分离的关系。
The yin and yang primordial qi (Yuan Qi, 元气) of the human body all originate from the lower part. Therefore, after discussing "Guangming" (Broad Enlightenment), the *Neijing* (Inner Canon) immediately mentions "Taichong" (Great Surge). The area of Taichong belongs to Shaoyin (Lesser Yin). Anterior to Shaoyin is Jueyin (Terminal Yin), whose region is known as the Sea of Blood (Xue Hai, 血海), which frequently surges essence and qi together with Taichong, irrigating and permeating the yin and yang above. Thus, the primordial qi and essence of humans all originate from below. However, rising from below, they divide into three pathways ascending: the yang pathway travels posterior to Shaoyin, running through the midline between the spine within the Taiyang (Greater Yang) meridian, thereby commanding all yang meridians; this vessel is named the Du Mai (Governor Vessel, 督脉). The yin pathway ascends from the anterior yin earth path, entering the exterior-interior relationship of the Yangming (Yang Brightness) meridian, thereby commanding all yin meridians; this vessel is named the Ren Mai (Conception Vessel, 任脉). The central pathway originates from the Sea of Blood, surging essence and qi upward to accumulate in the chest, forming Zong Qi (Gathering Qi, 宗气) to govern respiration; this vessel is named the Chong Mai (Penetrating Vessel, 冲脉). This qi resides in the Middle Jiao (Central Region, 中州) along with the Stomach Qi of Yangming, and also travels with Ying Qi (Nutritive Qi, 营气) through the twelve meridians.
I have examined that the Du Mai originates in the Bao Zhong (Uterus/Bladder Center, 胞中), ascends to the vertex, passing through Baihui (GV20) and Shenting (GV24); the Ren Mai originates below Zhongji (CV3) in the Bao Zhong, follows Guanyuan (CV4) and passes Chengjiang (CV24), meeting the Du Mai above; the Chong Mai originates in the Bao Zhong, ascends alongside the umbilicus, and meets at the throat. These three vessels originate from the Xia Ji (Lower Extreme/Huiyin, 下极), sharing one source but branching into three. Therefore, the Sages do not speak of Chong, Du, and Ren separately, but collectively name them "Taichong." Taichong refers to the ascent of the essence and qi of the whole body, not merely referring to the Sea of Blood.
Between the interior and exterior lies the Dai Mai (Belt Vessel, 带脉), which runs horizontally. It crosses the hypochondriac region, governed by Zhangmen (LR13) and Wushu (GB25), binding all meridians to maintain regularity above and below, restraining Ying Qi so it does not become lax. Its shape resembles a belt tied around the person hanging down in front, serving as a lock for essence and qi. This area is called "Lv" (Muscles of the Back, 膂), where the body's full strength emerges; the persistence of Lv Li (Back Strength, 膂力) is due to this.
"Wei" (Maintain, 维) implies maintenance and connection. While Yang meridians are commanded by the Du Mai and Yin meridians by the Ren Mai, there are specific vessels that must connect and support the scattered and converging points of these yin and yang meridians. Thus, there is the Yin Wei Mai (Yinkling Vessel, 阴维脉) to connect the yin meridians, and the Yang Wei Mai (Yangkling Vessel, 阳维脉) to connect the yang meridians. However, those capable of connecting must start from the root of yin and yang, possessing the vigorous emission of qi before they can connect. The Yang Wei Mai goes from Shaoyin to Taiyang, originating from Jinmen (BL63) of the Foot-Taiyang meridian, and meets five meridians (Hand-Shaoyang, Foot-Shaoyang, Hand-Yangming, Foot-Yangming) at Yangbai (GB14). The Yin Wei Mai slants from Shaoyin to Jueyin, originating from Zubin (KI9) of the Foot-Shaoyin meridian, ending at the front of the vertex. Shaoyin and Shaoyang are the root qi of yin and yang. Connecting yang must start from Shaoyin, indicating that yin is the root of yang. Connecting yin must start from Shaoyang, indicating that yang guides yin. Therefore, these two vessels are also the guidelines for Ying Qi.
The two Qiao Mai (Yinqiao and Yangqiao, 跷脉) derive their meaning from "Qiao," which signifies lifting or striding. Their qi is swift and fierce, similar to Wei Qi (Defensive Qi, 卫气), and both ascend to the eyes. However, their pathways differ from Wei Qi. The Yin Qiao emerges from yang and intersects with the Foot-Taiyang meridian, while the Yang Qiao enters yin and intersects with the Foot-Shaoyin meridian. Their qi and movement often arise from the harmony of the roots of yin and yang, enabling striding and ascending to nourish the head, converging at the eyes, thus ensuring proper opening and closing of the eyes. The statement "Yin meridians nourish the Zang organs, Yang meridians nourish the Fu organs" means that entering yin nourishes the Zang, and entering yang nourishes the Fu.
Regarding men and women, their pulse characteristics differ based on function: Men utilize yang, so their Qiao Mai focuses on yang; thus, men's pulses are predominantly associated with yang. Women utilize yin, so their Qiao Mai focuses on yin; thus, women's pulses are predominantly associated with yin. In summary, among the Eight Extraordinary Vessels, only the Dai Mai binds horizontally at the waist and back, while the other seven vessels pillar upwards from below. Although they have distinct pathways and numerous convergence points, since they all originate from Taiyang and Shaoyin, they all embody the meaning of "Taichong." Therefore, the Sages only mention Taichong and do not separately discuss Du, Ren, Wei, and Qiao, implying a relationship that is differentiated yet unified.