李濒湖曰∶凡人一身有经脉络脉。直行曰经。旁行曰。络经凡十二。手之三阴三阳。足
之三阴三阳是也。络凡十五。乃十二经各有一别络而脾又有一大络。并任督二络为十五也。共二
十七气。相随上下。如泉之流。如日月之行。不得休息。故阴脉营于五脏。阳脉营于六腑。
阴阳相贯。如环无端。莫知其纪。终而复始。其流溢之气。入于奇经。转相灌溉。内温脏腑
。外濡腠理。奇经凡八脉。不拘制于十二正经。无表里配合。故谓之奇。盖正经犹乎沟渠。
奇经犹夫湖泽。正经之脉隆盛。则溢于奇经。故越人比之天雨降下。沟渠溢满。滂霈妄行。
流于湖泽。此发灵素未发之秘者也。八脉载在群书。略而不悉。医不知此。罔探病机。仙不知
此。难安炉鼎云。奇经八脉者阴维也。阳维也。阴跷也。阳跷也。冲也。任也。督也。带也
。阳维起于诸阳之会。繇外踝而上行于卫分。阴维起于诸阴之交。繇内踝而上行于营分。所
以为一身之纲维也。阳跷起于跟中。循外踝上行于身之左右。阴跷起于跟中。循内踝上行于
身之左右。所以使机关之捷跷也。督脉起于会阴。循背而行于身之后。为阳脉之总督。故曰
阳脉之海。任脉起于会阴。循腹而行于身之前。为阴脉之承任。故曰阴脉之海。冲脉起于会
阴。夹脐而行。直冲于上为诸脉之冲要。故曰十二经脉之海。带脉则横围于腰。状如束带。
所以总约诸脉者也。是故阳维主一身之表阴维主一身之里。以乾坤言也。阳跷主一身左右之
阳阴跷主一身左右之。阴以东西言也。督主身后之阳任冲主身前之阴以南北言也。带脉横
束诸脉以六合言也。是故医而知乎八脉。则十二经十五络之大旨得矣。仙而知乎八脉。则龙虎
升降玄牝幽微之妙窍得矣。两手脉浮之俱有阳。沉之俱有阴。阴阳皆实盛者。此为冲督之脉
也。冲督之脉者十二经之道路也。冲督用事。则十二经不复朝于寸口。其人皆恍惚狐疑不省
必当犹豫而两心也。两手阳脉浮而细微。绵绵不可知。俱有阴脉。亦复细绵绵。此为阴跷阳
跷之脉也。此人曾有病鬼魅风死。若恍惚亡人为祸也。尺寸脉俱浮。直上直下。此为督脉。
腰背强直。不得俯仰。大人癫病。小儿风痫疾。尺寸脉俱牢。直上直下。此为冲脉胸中有病
寒疝也。难经曰∶奇经为病何如。然阳维维于阳。阴维维于阴。阴阳不能相维。则怅然失志
。溶溶不能自收。阴跷为病。阳缓而阴急。阳跷为病。阴缓而阳急。冲脉为病。逆气而里急
。督脉为病。脊强而厥。任脉之为病。其内若结。男子为七疝。女子为瘕聚。带之为病。腹
满腰溶溶若坐水中。阳维为病。苦寒热。阴维为病。苦心痛。此奇经脉之为病也。
李时珍说：大凡人的全身有经脉和络脉。直行的称为经。旁行的称为络。经共有十二条，就是手部的三条阴经、三条阳经，足部的三条阴经、三条阳经。络共有十五条，是十二经各有一条别络，加上脾脏又有一条大络，再加上任脉和督脉的络脉，合起来共十五条。总共二十七条气脉，相随上下运行，像泉水流动一样，像日月运行一样，不得休息。所以阴脉滋养五脏，阳脉滋养六腑。阴阳相互贯通，像一个圆环没有端点，不知道它的头绪，循环往复，终而复始。其中流溢的气血，进入奇经八脉，互相转输灌溉，对内温暖脏腑，对外滋润腠理（皮肤纹理及汗孔）。奇经共有八条脉，不受十二正经的限制，没有表里配合关系，所以称为“奇”。大概正经如同沟渠，奇经如同湖泽。当正经的气脉隆盛时，就会溢出到奇经中。所以扁鹊（越人）将其比作天降雨水，沟渠满溢，大雨滂沱肆意横流，流入湖泽。这是阐发《灵枢》《素问》未曾揭示的秘密啊。奇经八脉记载在各类医书中，但往往简略而不详细。医生如果不了解这些，就无法探求病机；修道之人如果不了解这些，也难以安顿炼丹的炉鼎。
所谓奇经八脉，是指阴维脉、阳维脉、阴跷脉、阳跷脉、冲脉、任脉、督脉、带脉。阳维脉起于诸阳经交会之处，从外踝向上行于卫分（体表防御之气）；阴维脉起于诸阴经交会之处，从内踝向上行于营分（体内营养之气）。它们作为全身的纲维。阳跷脉起于脚跟中部，沿外踝上行于身体左右两侧，用来使关节动作敏捷轻快。阴跷脉起于脚跟中部，沿内踝上行于身体左右两侧。督脉起于会阴穴，沿背部而行于身体后方，为所有阳脉的总督，所以称为“阳脉之海”。任脉起于会阴穴，沿腹部而行于身体前方，为所有阴脉的承担者，所以称为“阴脉之海”。冲脉起于会阴穴，夹脐部而行，直冲向上，是所有脉气的冲要之处，所以称为“十二经脉之海”。带脉则横向环绕腰部，形状像束带，用来总束约束诸脉。
因此，阳维脉主管一身之表，阴维脉主管一身之里，这是用乾坤（天地）来比喻。阳跷脉主管一身左右之阳，阴跷脉主管一身左右之阴，这是用东西方位来比喻。督脉主管身后之阳，任脉和冲脉主管身前之阴，这是用南北方位来比喻。带脉横向束约诸脉，这是用六合（四方加天地）来比喻。所以，医生如果通晓了八脉，就能掌握十二经和十五络的主要宗旨；修道之人如果通晓了八脉，就能领悟龙虎升降、玄牝幽微的精妙窍诀。
诊察两手脉象，浮取时都有阳脉，沉取时都有阴脉，阴阳都实盛，这是冲脉和督脉的脉象。冲脉和督脉是十二经运行的道路。当冲脉和督脉主事时，十二经的气血就不再朝注于寸口脉。这样的人常常神情恍惚、狐疑不定、神志不清，必定犹豫不决而两心并存。两手阳脉浮取细微，绵绵不绝难以感知，同时也有阴脉，同样细弱绵绵，这是阴跷脉和阳跷脉的脉象。这种人曾经患过重病，或被鬼魅风邪所伤，或者出现类似神魂离体的恍惚状态。尺部和寸部脉象都浮，直上直下，这是督脉的病脉。症状表现为腰背强直，不能俯仰。成人多见癫病，小儿多见风痫疾。尺部和寸部脉象都牢，直上直下，这是冲脉的病脉。症状表现为胸中有寒邪，或有疝气。
《难经》说：奇经发生病变是怎样的呢？回答是：阳维脉维系阳经，阴维脉维系阴经。如果阴阳不能相互维系，就会怅然若失、意志消沉，身体松懈无力，不能自我收持。阴跷脉发病，表现为阳侧松弛而阴侧拘急；阳跷脉发病，表现为阴侧松弛而阳侧拘急。冲脉发病，表现为气逆和腹部拘急。督脉发病，表现为脊背强直和厥逆。任脉发病，表现为体内如有结块，男子患七种疝气，女子患瘕聚（腹内结块）。带脉发病，表现为腹部胀满，腰部松软无力，好像坐在冷水中的感觉。阳维脉发病，苦于寒热往来；阴维脉发病，苦于心痛。这就是奇经八脉发生病变的情况。
Li Shizhen said: In the human body, there are Jing (Main) vessels and Luo (Collateral) vessels. Those that run straight are called Jing vessels. Those that branch off are called Luo vessels. There are twelve Jing vessels in total, namely the three Yin and three Yang vessels of the hand, and the three Yin and three Yang vessels of the foot. There are fifteen Luo vessels in total; these consist of one collateral from each of the twelve Jing vessels, plus one major collateral from the Spleen, along with the collaterals of the Ren (Conception Vessel) and Du (Governor Vessel), making fifteen in all. Together, they form twenty-seven Qi pathways, moving up and down together like flowing spring water or the movement of the sun and moon, never resting. Thus, the Yin vessels nourish the Zang organs (Solid organs), and the Yang vessels nourish the Fu organs (Hollow organs). Yin and Yang interconnect continuously like a circle without beginning or end, beyond comprehension, cycling endlessly. The overflowing Qi enters the Eight Extraordinary Vessels (Qi Jing Ba Mai), irrigating each other, warming the internal Zang-Fu organs, and moistening the Cou Li (skin texture and pores). There are eight Extraordinary Vessels in total, which are not constrained by the Twelve Regular Meridians and lack exterior-interior pairing, hence they are called "Extraordinary" (Qi). Generally speaking, the regular meridians are like irrigation ditches, while the extraordinary vessels are like lakes and marshes. When the Qi in the regular meridians becomes abundant, it overflows into the extraordinary vessels. Therefore, Bian Que (Yue Ren) compared this to rain falling from the sky: when ditches overflow, heavy rain flows wildly into the lakes. This reveals secrets not yet expounded in the *Ling Shu* and *Su Wen*. Although the Eight Extraordinary Vessels are recorded in various texts, they are often described briefly and incompletely. If physicians do not understand this, they cannot probe the pathogenesis; if Daoist cultivators do not understand this, they cannot properly manage the alchemical furnace and tripod.
The Eight Extraordinary Vessels are the Yin Wei (Linking) Vessel, Yang Wei (Linking) Vessel, Yin Qiao (Heel-Climbing) Vessel, Yang Qiao (Heel-Climbing) Vessel, Chong (Penetrating) Vessel, Ren (Conception) Vessel, Du (Governor) Vessel, and Dai (Belt) Vessel. The Yang Wei Vessel originates at the convergence of all Yang vessels, ascending from the lateral malleolus into the Wei (Defensive) level. The Yin Wei Vessel originates at the convergence of all Yin vessels, ascending from the medial malleolus into the Ying (Nutritive) level. They serve as the framework for the entire body. The Yang Qiao Vessel originates in the heel, follows the lateral malleolus, and ascends on both sides of the body, enabling agility and nimbleness of the joints. The Yin Qiao Vessel also originates in the heel, follows the medial malleolus, and ascends on both sides of the body. The Du Vessel originates at the Huiyin point (CV1), runs along the back, and governs the posterior aspect of the body, serving as the commander of all Yang vessels; thus, it is called the "Sea of Yang Vessels." The Ren Vessel originates at the Huiyin point, runs along the abdomen, and governs the anterior aspect of the body, serving as the bearer of all Yin vessels; thus, it is called the "Sea of Yin Vessels." The Chong Vessel originates at the Huiyin point, runs alongside the umbilicus, and rushes upward, acting as the crucial pathway for all vessels; thus, it is called the "Sea of the Twelve Regular Meridians." The Dai Vessel encircles the waist horizontally, resembling a belt, and serves to bind and regulate all the vessels.
Therefore, the Yang Wei Vessel governs the exterior of the body, and the Yin Wei Vessel governs the interior, analogous to Heaven and Earth (Qian and Kun). The Yang Qiao Vessel governs the Yang on both left and right sides, and the Yin Qiao Vessel governs the Yin on both left and right sides, analogous to East and West. The Du Vessel governs the Yang at the posterior, and the Ren and Chong Vessels govern the Yin at the anterior, analogous to North and South. The Dai Vessel binds the vessels horizontally, analogous to the Six Directions (Si Fang plus Heaven and Earth). Thus, if a physician understands the Eight Extraordinary Vessels, they grasp the main principles of the Twelve Regular Meridians and Fifteen Collaterals. If a Daoist cultivator understands the Eight Extraordinary Vessels, they comprehend the subtle mysteries of the ascent and descent of Dragon and Tiger, and the profound mechanisms of the Mysterious Female (Xuan Pin).
Regarding pulse diagnosis: If both hands show Yang pulses upon superficial palpation and Yin pulses upon deep palpation, and both Yin and Yang are excessively full and robust, this indicates the Chong and Du Vessels. The Chong and Du Vessels are the pathways for the Twelve Regular Meridians. When the Chong and Du Vessels are dominant, the Qi of the Twelve Regular Meridians no longer converges at the Cun Kou (radial artery) pulse position. Such individuals often exhibit mental confusion, doubtfulness, and lack of clarity, characterized by indecision and dual-mindedness. If the Yang pulses of both hands are superficial, fine, and thread-like, barely perceptible, and the Yin pulses are similarly fine and thread-like, this indicates the Yin Qiao and Yang Qiao Vessels. Such individuals may have previously suffered from severe illness, demonic wind invasion, or conditions resembling soul loss and hallucinations. If the Chi (Cun) and Cun (Guan) pulses at both positions are floating and move straight up and down, this indicates pathology of the Du Vessel, manifesting as stiffness and rigidity of the lower back and back, inability to bend or extend. In adults, this presents as Dian disease (epilepsy/psychosis); in children, it presents as Feng Xian Ji (infantile convulsions). If the Chi and Cun pulses are firm (Lao) and move straight up and down, this indicates pathology of the Chong Vessel, manifesting as cold in the chest or Hernia diseases.
The *Nan Jing* states: What are the manifestations of disease in the Extraordinary Vessels? The answer is: The Yang Wei Vessel links the Yang, and the Yin Wei Vessel links the Yin. If Yin and Yang cannot link each other, the person feels despondent and loses their will, with a flaccid body unable to control itself. Disease of the Yin Qiao Vessel presents with relaxation of the Yang side and tension of the Yin side. Disease of the Yang Qiao Vessel presents with relaxation of the Yin side and tension of the Yang side. Disease of the Chong Vessel presents with counterflow Qi and abdominal urgency. Disease of the Du Vessel presents with spinal rigidity and Jue (cold extremities/fainting). Disease of the Ren Vessel presents with internal knotting; in men, it manifests as Seven Types of Hernia; in women, as Zha Ju (abdominal masses). Disease of the Dai Vessel presents with abdominal fullness and a flaccid sensation in the waist, as if sitting in water. Disease of the Yang Wei Vessel involves suffering from alternating chills and fever. Disease of the Yin Wei Vessel involves suffering from heart pain. These are the pathological manifestations of the Extraordinary Vessels.