营气，阴气也，如地水之气，随天气以营运者也。天有经宿，地有经水，人有经脉。经
脉者，乃营运脏腑之血，以周于内外者也。脏属阴，故脏六经为阴，如手太阴肺、手少阴心
、手厥阴心包络、足太阴脾、足少阴肾、足厥阴肝是也。腑属阳，故腑六经为阳，如手阳明
大肠、手太阳小肠、手少阳三焦（右肾旁三焦腑）、足阳明胃、足太阳膀胱、足少阳胆是也。
阴之大者为太阴，太阴为开，敷布阴气者也；（太阴，三阴也。经曰∶三阴为母。）阴之小者
为
阴
，在
阳行身之侧面，在表里之间。）少阳为枢，转输阳气者也；两阳合明为阳明，（阳明行腹，在表之
里。）阳明为阖，收纳阳气者也。
然则阴阳分手足者何也？盖人有三焦（此三焦即三停），而三焦只是两焦，以人身中有膈
膜（遮蔽浊气，不使上熏心肺）。膈膜以上，肺与心与心包络，象天，经脉因行于手，故手三
阴从脏走手（阴从内起），手三阳从手走头（阳从外起，手三阳虽位居下焦，然与手三阴为表
里，直相联系，故亦走手）；膈膜以下诸脏腑，皆象地，经脉因行于足，故足三阳从头走足（
阳行于外），足三阴从足走腹（阴行于内）。象天者阴先而阳后，象地者阳先而阴后，此水火
既济，地天交泰之道也。
或曰∶经脉既有从腹走手、从手走头、从头走足、从足走腹之不同，何谓皆根于心乎？
既曰∶皆根于心，何又谓营出中焦？肺脉亦从中焦起乎？曰∶经脉根于心，而行于腹、行于手
、
，繁衍无已，而要皆原于根也。心脉下缘于胃脉，犹树之根须生于地下也。根于心者，大哉
干元，万物资始；缘于胃者，至哉坤元，万物资生。经曰∶心生血。又曰∶营气之道，内谷
为宝。谷入于胃，乃传之肺，精专者行于经隧，常营无已，终而复始，是谓天地之纪。盖谓
水谷精微之气，皆由胃出，而上注于心，奉心化赤为血，而上注于肺。阴随阳化，天气行而
营气与之俱行，故每日营气之行，皆从肺经始，地上承天也。由肺经下行而注于大肠经（肺
与大肠相表里），复上行而注于胃经，循注于脾经（脾与胃相表里），又上行而注于心经，由
心经下行而注于小肠经（心与小肠相表里），由是而注于膀胱经，循注于肾经（肾与膀胱相表
里），从肾注心包络（心肾相交），由心包络下行而注于三焦经（心包络与三焦相表里），从三
焦经复上行而注于胆经，循注于肝经（肝与胆相表里），至肝经而营气一周于身，经故曰厥阴
为阴之尽，厥阴为阖。尽而阖，故藏血。由肝经上行而复注于肺经，终而复始，如环无端，
一昼一夜，五十度周于身，经故曰五十营。
再以经脉营运于内外者析言之。手太阴肺脉根于心，缘于胃，而上通于肺，由肺下膈，
络大肠，还上膈，由肺系（喉管两旁，左是经脉管，右是络管）外行乳上三肋端，去中行旁开
六寸（同身寸法），横从腋下，达肘内，循臂前廉，入寸口，上鱼际（大指后肉隆起处），至手
大指内侧（少商穴）；其支者，循腕后入手次指内侧（商阳穴），而交手阳明。手阳明大肠脉，
外起手次指内侧，入合谷（俗名虎口），循臂外前廉达肩，入缺盆（肩下横骨陷中），内行络肺
，下膈，属大肠；从缺盆分支外行，直上颈侧，贯颊内，入上齿，还出，外行人中，挟鼻空
旁（迎香穴），而交足阳明。足阳明胃脉，外起鼻空旁，上行，当目下胞之中，下入上齿，还
出，挟口，绕腮，上耳前，至额角，下颈侧（结喉两旁人迎穴），入缺盆，再下行当乳之中，
内行下膈，属胃，络脾，挟脐旁入气街（毛际两旁）；胃口又生一支，亦挟脐旁入气街，外行
腿合缝，从合缝斜行腿面，直至足中指之外侧；又生一小支，别跗上，入大指间，出其端（
厉兑穴），而交足太阴。足太阴脾脉，外起足大指端之内侧，循内踝前廉，上股（大腿）内廉
入腹，行季胁（在足少阳、厥阴之里一行），上膈，挟咽，连舌本，散舌下；其支者，复从胃
别上膈，注心中（从胃之别络注心，浊气乃不上僭），而交手少阴。手少阴心脉，起于心中，
出属心系，心系上与肺通，由肺叶而下，曲折向后，贯脊髓，通于肾（肺、心、肾，一气相
通），转而向前，下膈，络小肠；其支者，从心系上挟咽，系于目；其直者，外行腋下，循
肘臂内后廉，至小指内侧（少冲穴），而交手太阳。手太阳小肠脉，外起手小指内侧，而行外
侧（少泽穴），循肘外后廉，过肩后廉，入缺盆，内行络心，下膈，抵胃，属小肠；其支者，
由缺盆，交肩，贯颈颊，至目锐 （目外角），却入耳中；其支者，由耳前斜络于颧，至目内
（目内角）而交足太阳。足太阳膀胱脉，外起目内 ，上额交巅，分一小支，从巅至耳上角
，后行，下项，循肩后，分二大支∶一大支挟脊旁开寸半第一行，抵腰中，腰中有四空，内
行络肾，属膀胱，其直者，从腰下外行，贯臀，入 中（膝后曲处委中穴）；一大支又从肩膊
后，左右分下，贯胛膂（脊两旁肉为膂），挟脊旁开三寸第二行，入 中，贯 内（足肚）
，出外踝，至足小指外侧端（至阴穴），以交足少阴。足少阴肾脉，外起小指下，斜趋足心，
循内踝，入足后跟，上行股内后廉，贯脊里，属肾，络膀胱；其直者，从股内前行至合缝，
由合缝上行入腹，去腹中行旁开一寸，至脐入肾，由脐上行，去中行旁开一寸五分，从肾上
贯肝膈，又上行，去中行旁开二寸，至胸中入肺，循喉咙，挟舌本；其支者，从肺出，络心
，注胸中（肺、心、心包络、肝四脏，皆与肾经相通），以交手厥阴。手厥阴心包络脉，内起
胸中，下膈，络三焦；其支者，由胸中出胁抵腋，循心、肺二经之间，外行，起腋下三寸，
乳外侧一寸许，向外上转，循臂肘内两筋之间，入掌中（劳宫穴），至中指，出其端（中冲穴）
；其支者，别掌中，行小指内之次指端（关冲穴），以交手少阳。手少阳三焦脉，外起小指次
指之外侧，上循手臂外两骨中间，贯肘上肩，由肩上项，交出胆经之后，入缺盆，内行，布
膻中，散络心包，下膈，属三焦；其支者，外行，入缺盆，上项，系耳后，出耳上角，以屈
下颊至 （目下为 ）；其支者，从耳后，内入耳中，外走耳前，交动脉间，至目锐
，而交足少阳。足少阳胆脉，外起目锐 ，上头角，下耳后，循颈侧，行三焦经之前，后
入缺盆；一支从耳后，入耳中，走耳前，还至目锐 ；一支别锐 ，下大迎（胃经穴，在颔
前一寸三分动脉陷中），还行于 ，合三焦经，下加颊车（耳下穴名），行颈侧，亦入缺
盆，由缺盆内行胸中，贯膈，络肝，属胆，循胁里，出气街（毛际两旁动脉），绕毛际，横入
髀厌中（胯骨）；其直者，从缺盆外行，过肩，下腋，走身侧之季胁（胁骨下尽处），下髀厌，
行膝外廉，至外踝前，还行足跗，至足小指次指之外侧（窍阴穴），生一小支，别足跗，下足
大指岐骨，贯爪甲，出三毛（大指爪甲后为三毛，大敦穴），以交足厥阴。足厥阴肝脉，外起
足大指爪甲端，还行足跗，走内踝，出脾脉之后，入 中，循股阴，内行，绕阴器，抵小腹
，还行季胁（肝经章门穴），斜上，直乳下二肋端，挟胃，属肝，络胆，贯膈，布胁肋，循喉
咙，上连目系，外行出额，与督脉会于巅；一支外行，从目系下颊，还唇；一支内行，从肝
别贯膈，上注于肺，终而复始。此经脉也。
所谓十二络者，即十二经之别，所以回血入于经者也。别有脾之大络（名曰大包），出渊
液穴下三寸（属胆经），布胸胁，实则身尽痛，虚则百节皆纵。又有胃之大络（名曰虚里），贯
膈，络肺，出于左乳下，其动应衣，乃十二经脉之宗气（土为万物之母，故亦名宗气）。盛喘
数绝者，病在中，结而横，有积也，绝不至则死，动甚者，宗气泄也。知经络之所行，则知
病之所在矣。
若夫奇经（无脏腑配合之经），即足六经之别。考冲、任、督，一源而三脉，皆起于中极
下（中极穴，在脐下四寸）。任脉由中极下之会阴穴，当脐中而上，至承浆穴而止。冲脉由中
极挟脐旁而上，至胸中而散。督脉由中极下行，转而向后，自长强穴（尾闾骨端）而上行于背
之中行，至龈交穴（牙龈内），而止。任、督二脉，一行身前，以任养诸阴，一行身后，以总督
诸阳，犹天地之有子午可以分、可以合。分之以见阴阳之对待，合之以见阴阳之环行，一而
二，二而一者也。阴维维一身之阴脉，阳维维一身之阳脉，又与任、督二脉相辅而行者也，
阴跷起于足内踝之照海穴（属足少阴经），侧行而上于目内 之睛明穴（属足太阳经）；阳
跷起于足外踝之申脉穴（属足太阳经），侧行而亦上于目内 之睛明穴。阴维、阳维、阴
跷、阳跷四脉，犹八方四正之有四维也。带脉起于季胁下之章门穴，为足厥阴、少
阳之会，与天枢穴平，犹天之有天腰横带也。知奇经之附正经而行，正经治而奇经亦治，亦
何必深言治法，以矜奇炫异乎！
营气，属于阴气，就像大地上的水气，随着天气的运行而周流全身。天有经宿（一昼夜），地有经水（潮汐），人有经脉。经脉，是运行脏腑之血，以循环于身体内外的通道。脏属阴，所以六条阴经为阴经，如手太阴肺经、手少阴心经、手厥阴心包络经、足太阴脾经、足少阴肾经、足厥阴肝经。腑属阳，所以六条阳经为阳经，如手阳明大肠经、手太阳小肠经、手少阳三焦经（位于右肾旁）、足阳明胃经、足太阳膀胱经、足少阳胆经。
阴气中盛大者为太阴，太阴主“开”，负责敷布阴气；（太阴即三阴之首。经典说：三阴为母。）阴气中小盛者为少阴，行于身之侧面，处于表里之间；少阳主“枢”，负责转输阳气；两阳合明者为阳明，（阳明行于腹部，在表之里。）阳明主“阖”，负责收纳阳气。
那么为什么阴阳要分出手经和足经呢？大概因为人有三焦（此处三焦指上、中、下三停），而三焦实际上只是两个焦区，因为人身中有膈膜（遮蔽浊气，不使其上熏心肺）。膈膜以上，肺、心与心包络，象征天，经脉因此行于手部，所以手三阴从内脏走向手部（阴气从内起），手三阳从手部走向头部（阳气从外起，手三阳虽位居下焦，但与手三阴互为表里，直接相连，所以也走手）；膈膜以下的诸脏腑，都象征地，经脉因此行于足部，所以足三阳从头部走向足部（阳气行于外），足三阴从足部走向腹部（阴气行于内）。象征天的部位，阴先阳后；象征地的部位，阳先阴后，这就是水火既济、地天交泰的道理。
有人问：经脉既然有从腹走手、从手走头、从头走足、从足走腹的不同，为什么说都根源于心呢？既然说都根源于心，为什么又说营气出自中焦？肺脉也是从中焦起始的吗？回答说：经脉根源于心，而行于腹、行于手、行于头、行于足，繁衍无穷，但归根结底都源自根源。心脉向下连接胃脉，就像树的根须生于地下一样。根于心者，正如乾元伟大，万物由此开始；缘于胃者，正如坤元至善，万物由此生长。经典说：心生血。又说：营气的生成，以内谷为宝。谷物进入胃中，然后传送给肺，其中精纯的部分运行于经络隧道，常年营运不止，终而复始，这被称为天地运行的纲纪。意思是说，水谷精微之气，都由胃产生，而上注于心，奉心化赤成为血液，再上注于肺。阴随阳转化，天气运行而营气随之俱行，所以每日营气的运行，都从肺经开始，这是地上承天的表现。由肺经下行注入大肠经（肺与大肠相表里），又上行注入胃经，顺行注入脾经（脾与胃相表里），再上行注入心经，由心经下行注入小肠经（心与小肠相表里），由此注入膀胱经，顺行注入肾经（肾与膀胱相表里），从肾注入心包络（心肾相交），由心包络下行注入三焦经（心包络与三焦相表里），从三焦经又上行注入胆经，顺行注入肝经（肝与胆相表里），到了肝经，营气就在周身循环一周了，所以经典说厥阴为阴之尽，厥阴主“阖”。尽而阖，所以能藏血。由肝经上行又复注于肺经，终而复始，如环无端，一昼一夜，循环五十周于身，所以经典说“五十营”。
再从经脉营运于内外的角度详细分析。手太阴肺脉根于心，缘于胃，而上通于肺，由肺下膈，络属大肠，还上膈，由肺系（喉管两旁，左是经脉管，右是络管）外行于乳上三肋端，距正中中线旁开六寸（同身寸法），横向经过腋下，到达肘内，循臂前廉，入寸口，上鱼际（大拇指后肉隆起处），至手大拇指内侧（少商穴）；其支脉，循腕后入手次指内侧（商阳穴），而交手阳明大肠经。手阳明大肠脉，外起手次指内侧，入合谷（俗名虎口），循臂外前廉达肩，入缺盆（肩下横骨陷中），内行络肺，下膈，属大肠；从缺盆分支外行，直上颈侧，贯颊内，入上齿，还出，外行人中，挟鼻空旁（迎香穴），而交足阳明胃经。足阳明胃脉，外起鼻空旁，上行，当目下胞之中，下入上齿，还出，挟口，绕腮，上耳前，至额角，下颈侧（结喉两旁人迎穴），入缺盆，再下行当乳之中，内行下膈，属胃，络脾，挟脐旁入气街（毛际两旁）；胃口又生一支，亦挟脐旁入气街，外行腿合缝，从合缝斜行腿面，直至足中指之外侧；又生一小支，别跗上，入大指间，出其端（厉兑穴），而交足太阴脾经。足太阴脾脉，外起足大指端之内侧，循内踝前廉，上股（大腿）内廉入腹，行季胁（在足少阳、厥阴之里一行），上膈，挟咽，连舌本，散舌下；其支脉，复从胃别上膈，注心中（从胃之别络注心，浊气乃不上僭），而交手少阴心经。手少阴心脉，起于心中，出属心系，心系上与肺通，由肺叶而下，曲折向后，贯脊髓，通于肾（肺、心、肾，一气相通），转而向前，下膈，络小肠；其支脉，从心系上挟咽，系于目；其直者，外行腋下，循肘臂内后廉，至小指内侧（少冲穴），而交手太阳小肠经。手太阳小肠脉，外起手小指内侧，而行外侧（少泽穴），循肘外后廉，过肩后廉，入缺盆，内行络心，下膈，抵胃，属小肠；其支脉，由缺盆，交肩，贯颈颊，至目锐眦（目外角），却入耳中；其支脉，由耳前斜络于颧，至目内眦（目内角）而交足太阳膀胱经。足太阳膀胱脉，外起目内眦，上额交巅，分一小支，从巅至耳上角，后行，下项，循肩后，分二大支：一大支挟脊旁开寸半第一行，抵腰中，腰中有四空，内行络肾，属膀胱，其直者，从腰下外行，贯臀，入腘中（膝后曲处委中穴）；一大支又从肩膊后，左右分下，贯胛膂（脊两旁肉为膂），挟脊旁开三寸第二行，入腘中，贯腨内（足肚），出外踝，至足小指外侧端（至阴穴），以交足少阴肾经。足少阴肾脉，外起小指下，斜趋足心，循内踝，入足后跟，上行股内后廉，贯脊里，属肾，络膀胱；其直者，从股内前行至合缝，由合缝上行入腹，去腹中行旁开一寸，至脐入肾，由脐上行，去中行旁开一寸五分，从肾上贯肝膈，又上行，去中行旁开二寸，至胸中入肺，循喉咙，挟舌本；其支脉，从肺出，络心，注胸中（肺、心、心包络、肝四脏，皆与肾经相通），以交手厥阴心包络经。手厥阴心包络脉，内起胸中，下膈，络三焦；其支脉，由胸中出胁抵腋，循心、肺二经之间，外行，起腋下三寸，乳外侧一寸许，向外上转，循臂肘内两筋之间，入掌中（劳宫穴），至中指，出其端（中冲穴）；其支脉，别掌中，行小指内之次指端（关冲穴），以交手少阳三焦经。手少阳三焦脉，外起小指次指之外侧，上循手臂外两骨中间，贯肘上肩，由肩上项，交出胆经之后，入缺盆，内行，布膻中，散络心包，下膈，属三焦；其支脉，外行，入缺盆，上项，系耳后，出耳上角，以屈下颊至䪼（目下为䪼）；其支脉，从耳后，内入耳中，外走耳前，交动脉间，至目锐眦，而交足少阳胆经。足少阳胆脉，外起目锐眦，上头角，下耳后，循颈侧，行三焦经之前，后入缺盆；一支从耳后，入耳中，走耳前，还至目锐眦；一支别锐眦，下大迎（胃经穴，在颔前一寸三分动脉陷中），还行于䪼，合三焦经，下加颊车（耳下穴名），行颈侧，亦入缺盆，由缺盆内行胸中，贯膈，络肝，属胆，循胁里，出气街（毛际两旁动脉），绕毛际，横入髀厌中（胯骨）；其直者，从缺盆外行，过肩，下腋，走身侧之季胁（胁骨下尽处），下髀厌，行膝外廉，至外踝前，还行足跗，至足小指次指之外侧（窍阴穴），生一小支，别足跗，下足大指岐骨，贯爪甲，出三毛（大指爪甲后为三毛，大敦穴），以交足厥阴肝经。足厥阴肝脉，外起足大指爪甲端，还行足跗，走内踝，出脾脉之后，入腘中，循股阴，内行，绕阴器，抵小腹，还行季胁（肝经章门穴），斜上，直乳下二肋端，挟胃，属肝，络胆，贯膈，布胁肋，循喉咙，上连目系，外行出额，与督脉会于巅；一支外行，从目系下颊，还唇；一支内行，从肝别贯膈，上注于肺，终而复始。这就是经脉的循行路线。
所谓十二络脉，就是十二经的别络，作用是引导血液回归经脉。另有脾之大络（名叫大包），出于渊液穴下三寸（属胆经），布散于胸胁，实证则全身疼痛，虚证则百节皆松弛无力。又有胃之大络（名叫虚里），贯穿膈，络肺，出于左乳下，其跳动应衣，这是十二经脉的宗气（土为万物之母，故亦名宗气）。喘促且脉搏数绝的，病在中焦；结聚而横硬的，有积滞；脉搏断绝不至的则死，跳动过盛的，是宗气外泄。知道了经络的循行，就知道疾病的所在了。
至于奇经（没有脏腑配合的经脉），就是足六经的别络。考察冲、任、督，一源而三脉，都起于中极下（中极穴，在脐下四寸）。任脉由中极下的会阴穴，当脐中而上，至承浆穴而止。冲脉由中极挟脐旁而上，至胸中而散。督脉由中极下行，转而向后，自长强穴（尾闾骨端）而上行于背之中行，至龈交穴（牙龈内），而止。任、督二脉，一行身前，以任养诸阴，一行身后，以总督诸阳，犹如天地有子午可以分、可以合。分之以见阴阳之对待，合之以见阴阳之环行，是一而二，二而一的关系。阴维维系一身之阴脉，阳维维系一身之阳脉，又与任、督二脉相辅而行。阴跷起于足内踝之照海穴（属足少阴经），侧行而上于目内眦之睛明穴（属足太阳经）；阳跷起于足外踝之申脉穴（属足太阳经），侧行而亦上于目内眦之睛明穴。阴维、阳维、阴跷、阳跷四脉，犹如八方四正之有四维。带脉起于季胁下之章门穴，为足厥阴、少阳之会，与天枢穴平，犹如天有天腰横带一般。知道奇经依附正经而行，正经治疗好了奇经也就治好了，又何必深言治法，以炫耀奇特怪异呢！
Ying Qi (Nutritive Qi) is Yin Qi (Yin energy), similar to the vapor of water from the earth, circulating and operating along with Tian Qi (Heavenly Qi). Heaven has a diurnal cycle (Jing Su), Earth has tidal waters (Jing Shui), and humans have meridians (Jing Mai). Meridians are the pathways that circulate blood within the Zang organs to traverse the interior and exterior. Zang organs belong to Yin; thus, the six Yin meridians are Yin, such as the Hand Taiyin Lung Meridian, Hand Shaoyin Heart Meridian, Hand Jueyin Pericardium Meridian, Foot Taiyin Spleen Meridian, Foot Shaoyin Kidney Meridian, and Foot Jueyin Liver Meridian. Fu organs belong to Yang; thus, the six Yang meridians are Yang, such as the Hand Yangming Large Intestine Meridian, Hand Taiyang Small Intestine Meridian, Hand Shaoyang Sanjiao (Triple Burner) Meridian (located beside the right kidney), Foot Yangming Stomach Meridian, Foot Taiyang Bladder Meridian, and Foot Shaoyang Gallbladder Meridian.
Among Yin, the grand aspect is Taiyin, which governs "Opening" (Kai) and spreads Yin Qi. (Taiyin refers to the Three Yin; the Classics state: "Three Yin serves as the mother.") The lesser aspect of Yin is Shaoyin, running on the lateral side of the body, situated between the exterior and interior. Shaoyang governs the "Pivot" (Shu) and transports Yang Qi. When two Yangs combine to illuminate, it is called Yangming, (Yangming runs along the abdomen, inside the exterior.) Yangming governs "Closing" (He) and receives Yang Qi.
Why are Yin and Yang divided into Hand and Foot meridians? It is because humans have the Sanjiao (Triple Burner) (here referring to the upper, middle, and lower sections), but essentially there are only two burners, due to the presence of the diaphragm in the human body (which blocks turbid Qi from ascending to熏 the Heart and Lungs). Above the diaphragm, the Lungs, Heart, and Pericardium symbolize Heaven; therefore, meridians run through the hands. Thus, the three Hand Yin meridians travel from the Zang organs to the hands (Yin originates internally), and the three Hand Yang meridians travel from the hands to the head (Yang originates externally; although Hand Yang meridians are located in the lower burner, they are exterior-interior paired with Hand Yin meridians and directly connected, so they also travel to the hands). Below the diaphragm, all Zang-Fu organs symbolize Earth; therefore, meridians run through the feet. Thus, the three Foot Yang meridians travel from the head to the feet (Yang travels externally), and the three Foot Yin meridians travel from the feet to the abdomen (Yin travels internally). In areas symbolizing Heaven, Yin precedes and Yang follows; in areas symbolizing Earth, Yang precedes and Yin follows. This is the way of Water and Fire interacting perfectly (Shui Huo Ji Ji) and Earth and Heaven communicating smoothly (Di Tian Jiao Tai).
One might ask: Since meridians differ in their paths—some from abdomen to hand, some from hand to head, some from head to foot, some from foot to abdomen—how can it be said that they all root in the Heart? If they all root in the Heart, why is it also said that Ying Qi emerges from the Middle Burner? Does the Lung meridian also originate from the Middle Burner? The answer is: Meridians root in the Heart, yet travel through the abdomen, hands, head, and feet, proliferating endlessly, but ultimately originating from the root. The Heart meridian connects downward to the Stomach meridian, just as tree roots grow underground. Rooting in the Heart corresponds to the greatness of Qianyuan (Creative Primal Force), from which all things begin; connecting to the Stomach corresponds to the perfection of Kunyuan (Receptive Primal Force), by which all things are nourished. The Classics state: "The Heart generates Blood." It also states: "In the path of Ying Qi, internal grain is precious." Grain enters the Stomach, then transmits to the Lungs; its purest essence travels through the meridian tunnels, circulating ceaselessly, ending and beginning again. This is called the discipline of Heaven and Earth. It means that the Qi of refined water and grain all emanate from the Stomach, ascend to the Heart, where the Heart transforms it into red blood, which then ascends to the Lungs. Yin transforms following Yang; as Heavenly Qi moves, Ying Qi moves with it. Therefore, daily circulation of Ying Qi always begins with the Lung Meridian, representing Earth receiving support from Heaven. From the Lung Meridian, it descends and pours into the Large Intestine Meridian (Lung and Large Intestine are exterior-interior pairs), then ascends and pours into the Stomach Meridian, flows into the Spleen Meridian (Spleen and Stomach are exterior-interior pairs), ascends again to pour into the Heart Meridian, descends from the Heart Meridian to pour into the Small Intestine Meridian (Heart and Small Intestine are exterior-interior pairs), thereby pouring into the Bladder Meridian, flows into the Kidney Meridian (Kidney and Bladder are exterior-interior pairs), pours from the Kidney into the Pericardium (Heart and Kidney interact), descends from the Pericardium to pour into the Sanjiao Meridian (Pericardium and Sanjiao are exterior-interior pairs), ascends from the Sanjiao Meridian to pour into the Gallbladder Meridian, flows into the Liver Meridian (Liver and Gallbladder are exterior-interior pairs). Upon reaching the Liver Meridian, Ying Qi completes one circuit around the body. Hence, the Classics say Jueyin is the end of Yin, and Jueyin governs Closing. End and Close, thus it stores Blood. From the Liver Meridian, it ascends and pours back into the Lung Meridian, ending and beginning again, like a circle without end. In one day and night, it circulates fifty times around the body, hence the Classics call it "Fifty Circulations" (Wu Shi Ying).
Let us analyze further the operation of meridians in the interior and exterior. The Hand Taiyin Lung Meridian roots in the Heart, connects to the Stomach, and ascends to the Lungs. From the Lungs, it passes below the diaphragm, connects to the Large Intestine, returns above the diaphragm, and from the Lung system (the sides of the trachea, left being the meridian vessel, right being the collateral vessels), it runs externally over the upper three ribs of the breast, six cun lateral to the midline (using the same-body inch method), horizontally from under the axilla, reaches the inner elbow, follows the anterior border of the arm, enters the Cun Kou pulse point, ascends to the Yu Ji (the fleshy mound behind the thumb), and reaches the medial side of the thumb (Shaoshang acupoint). Its branch follows the wrist posteriorly, enters the medial side of the index finger (Shangyang acupoint), and intersects with the Hand Yangming Large Intestine Meridian. The Hand Yangming Large Intestine Meridian starts externally at the medial side of the index finger, enters Hegu (commonly known as Tiger's Mouth), follows the anterior lateral border of the arm to the shoulder, enters the Quepen depression (depression below the clavicle), internally connects to the Lungs, passes below the diaphragm, and belongs to the Large Intestine. A branch from Quepen runs externally, straight up the neck side, penetrates the cheek internally, enters the upper teeth, emerges, runs externally into the philtrum, flanks the nasal cavity (Yingxiang acupoint), and intersects with the Foot Yangming Stomach Meridian. The Foot Yangming Stomach Meridian starts externally beside the nasal cavity, ascends, centers below the eye, descends into the upper teeth, emerges, flanks the mouth, wraps around the cheekbone, ascends before the ear, reaches the forehead corner, descends the neck side (Renying acupoint beside the Adam's apple), enters Quepen, descends again to the center of the breast, internally passes below the diaphragm, belongs to the Stomach, connects to the Spleen, flanks the navel, and enters the Qijie (bilateral groins). Another branch from the stomach opening also flanks the navel to enter Qijie, runs externally along the thigh seam, diagonally across the leg surface, to the outer side of the middle toe. A small branch diverges on the dorsum of the foot, enters between the big toes, and exits at the tip (Lidui acupoint), intersecting with the Foot Taiyin Spleen Meridian. The Foot Taiyin Spleen Meridian starts externally at the medial tip of the big toe, follows the anterior border of the medial malleolus, ascends along the medial thigh into the abdomen, runs along the hypochondrium (inside the Foot Shaoyang and Jueyin meridians), ascends through the diaphragm, flanks the throat, connects to the base of the tongue, and scatters under the tongue. Its branch diverges from the Stomach, ascends through the diaphragm, and pours into the Heart (collaterals from the Stomach pour into the Heart, preventing turbid Qi from counterflowing), intersecting with the Hand Shaoyin Heart Meridian. The Hand Shaoyin Heart Meridian originates in the Heart, exits to belong to the Heart system, which connects upward to the Lungs. Descending from the lung lobes, it curves backward, penetrates the spinal cord, and communicates with the Kidneys (Lungs, Heart, and Kidneys share one Qi). Turning forward, it passes below the diaphragm and connects to the Small Intestine. Its branch ascends from the Heart system, flanks the throat, and ties to the eyes. Its main trunk runs externally under the axilla, follows the posterior medial border of the elbow and arm, reaches the medial side of the little finger (Shaochong acupoint), and intersects with the Hand Taiyang Small Intestine Meridian. The Hand Taiyang Small Intestine Meridian starts externally at the medial side of the little finger, runs to the lateral side (Shaoze acupoint), follows the posterior lateral border of the elbow, passes the posterior shoulder border, enters Quepen, internally connects to the Heart, passes below the diaphragm, reaches the Stomach, and belongs to the Small Intestine. Its branch goes from Quepen, crosses the shoulder, penetrates the neck and cheek, reaches the outer canthus (eye corner), and enters the ear. Another branch from the ear front obliquely connects to the zygoma, reaches the inner canthus, and intersects with the Foot Taiyang Bladder Meridian. The Foot Taiyang Bladder Meridian starts externally at the inner canthus, ascends the forehead, crosses the vertex. A small branch goes from the vertex to the upper angle of the ear, runs posteriorly, descends the nape, follows the posterior shoulder, and divides into two major branches: one branch flanks the spine 1.5 cun laterally in the first row, reaches the waist. There are four spaces in the waist; internally connecting to the Kidneys, it belongs to the Bladder. Its straight part descends from the waist externally, penetrates the buttocks, and enters the popliteal fossa (Weizhong acupoint). Another major branch descends from the posterior shoulder, dividing left and right, penetrating the scapular muscles (muscles beside the spine are called Lü), flanking the spine 3 cun laterally in the second row, entering the popliteal fossa, penetrating the calf muscles, exiting the lateral malleolus, and reaching the lateral tip of the little toe (Zhiyin acupoint), intersecting with the Foot Shaoyin Kidney Meridian. The Foot Shaoyin Kidney Meridian starts externally below the little toe, slants toward the sole, follows the medial malleolus, enters the heel, ascends along the posterior medial thigh, penetrates the spine interior, belongs to the Kidneys, and connects to the Bladder. Its straight part proceeds anteriorly from the thigh to the groin, ascends from the groin into the abdomen, 1 cun lateral to the abdominal midline, enters the Kidney at the navel. Ascending from the navel, 1.5 cun lateral to the midline, it passes through the Kidney, pierces the Liver and diaphragm, ascends again 2 cun lateral to the midline, enters the chest and Lungs, follows the throat, flanks the tongue base. Its branch emerges from the Lungs, connects to the Heart, and pours into the chest (the Lungs, Heart, Pericardium, and Liver all communicate with the Kidney Meridian), intersecting with the Hand Jueyin Pericardium Meridian. The Hand Jueyin Pericardium Meridian originates internally in the chest, passes below the diaphragm, and connects to the Sanjiao. Its branch emerges from the chest, exits the costal margin to the axilla, runs between the Heart and Lung meridians, externally starts 3 cun under the axilla, about 1 cun lateral to the breast, turns outward and upward, follows between the two tendons of the inner elbow and arm, enters the palm center (Laogong acupoint), reaches the middle finger, and exits at the tip (Zhongchong acupoint). Its branch diverges from the palm center, runs to the tip of the index finger next to the little finger (Guanchong acupoint), intersecting with the Hand Shaoyang Sanjiao Meridian. The Hand Shaoyang Sanjiao Meridian starts externally at the lateral side of the index and middle fingers, ascends between the two bones of the forearm, penetrates the elbow and ascends the shoulder, goes from the shoulder to the neck, emerges posterior to the Gallbladder Meridian, enters Quepen, internally distributes at the Shanzhong, scatters and connects to the Pericardium, passes below the diaphragm, and belongs to the Sanjiao. Its branch runs externally, enters Quepen, ascends the neck, ties behind the ear, emerges at the upper angle of the ear, curves down the cheek to the orbital region (orbital region is called Bi); another branch from behind the ear enters the ear internally, exits anterior to the ear, intersects between arteries, reaches the outer canthus, and intersects with the Foot Shaoyang Gallbladder Meridian. The Foot Shaoyang Gallbladder Meridian starts externally at the outer canthus, ascends the head corner, descends behind the ear, follows the neck side, runs anterior to the Sanjiao Meridian, and enters Quepen. One branch goes from behind the ear, enters the ear, walks anterior to the ear, returns to the outer canthus. Another branch diverges from the outer canthus, descends to Daying (Stomach Meridian acupoint, 1.3 cun anterior to the jaw in the arterial depression), returns to the orbital region, combines with the Sanjiao Meridian, descends to Jiache (acupoint below the ear), runs along the neck side, and also enters Quepen. From Quepen, it runs internally through the chest, pierces the diaphragm, connects to the Liver, belongs to the Gallbladder, follows the interior of the hypochondrium, exits at Qijie (arteries in the bilateral groins), wraps around the pubic region, and transversely enters the hip joint (thigh bone). Its straight part runs externally from Quepen, passes the shoulder, descends under the axilla, walks along the lateral hypochondrium (end of the rib cage), descends the hip joint, runs along the lateral knee, reaches the anterior lateral malleolus, returns along the foot dorsum, reaches the lateral side of the fourth toe (Qiaoyin acupoint). A small branch diverges from the foot dorsum, descends the metatarsal bone of the big toe, penetrates the nail bed, and exits at the hair tuft (hair behind the big toe nail is called Sanmao, Dadun acupoint), intersecting with the Foot Jueyin Liver Meridian. The Foot Jueyin Liver Meridian starts externally at the lateral edge of the big toe nail, returns along the foot dorsum, walks the medial malleolus, emerges posterior to the Spleen Meridian, enters the popliteal fossa, follows the medial thigh, runs internally, surrounds the genitalia, reaches the lower abdomen, returns along the hypochondrium (Zhangmen acupoint of the Liver Meridian),斜 upwards, straight to the lower end of the second rib under the breast, flanks the Stomach, belongs to the Liver, connects to the Gallbladder, pierces the diaphragm, distributes in the hypochondrium, follows the throat, ascends to connect to the eye system, runs externally out of the forehead, and meets the Du Meridian at the vertex. One branch runs externally from the eye system down the cheek, returns to the lips. One branch runs internally, diverges from the Liver, pierces the diaphragm, and ascends to pour into the Lungs, ending and beginning again. These are the meridians.
The so-called Twelve Collaterals are the divergent branches of the twelve meridians, serving to return blood into the meridians. There is additionally the Great Collateral of the Spleen (named Dabao), emerging three cun below the Yuanli acupoint (belonging to the Gallbladder Meridian), distributing in the chest and hypochondrium. In excess conditions, the whole body aches; in deficiency conditions, all joints become lax. There is also the Great Collateral of the Stomach (named Xuli), piercing the diaphragm, connecting to the Lungs, emerging below the left breast. Its pulsation is visible through clothing; this is the Zong Qi (Gathering Qi) of the twelve meridians (Earth is the mother of all things, hence also named Zong Qi). Rapid panting and frequent interruption indicate disease in the middle jiao; knotted and hard indicates accumulation; absence of pulse indicates death; excessive pulsation indicates leakage of Zong Qi. Knowing the course of the meridians allows one to know the location of disease.
As for the Extraordinary Vessels (meridians without paired Zang-Fu organs), they are the divergences of the six Foot meridians. Examining Chong, Ren, and Du, they share one source but three vessels, all originating below Zhongji (Zhongji acupoint, 4 cun below the umbilicus). The Ren Meridian goes from the Huiyin acupoint below Zhongji, centers at the umbilicus and ascends, stopping at Chengjiang acupoint. The Chong Meridian goes from Zhongji, flanking the umbilicus and ascending, dispersing in the chest. The Du Meridian descends from Zhongji, turns backward, ascends from Changqiang acupoint (tip of the coccyx) along the midline of the back, stopping at Yinjiao acupoint (inside the gums). The Ren and Du meridians, one running along the anterior body to nourish all Yin, and one running along the posterior body to supervise all Yang, are like Heaven and Earth having Zi and Wu directions that can be separated or combined. Separated to show the opposition of Yin and Yang, combined to show the circular movement of Yin and Yang; they are one becoming two, and two becoming one. Yin Wei maintains the Yin meridians of the body; Yang Wei maintains the Yang meridians of the body; they assist the Ren and Du meridians in their courses. Yin Qiao starts at Zhaohai acupoint on the medial malleolus (Foot Shaoyin Meridian), runs laterally upward to Jingming acupoint at the inner canthus (Foot Taiyang Meridian). Yang Qiao starts at Shenmai acupoint on the lateral malleolus (Foot Taiyang Meridian), runs laterally upward also to Jingming acupoint at the inner canthus. The Yin Wei, Yang Wei, Yin Qiao, and Yang Qiao four vessels are like the Four Dimensions of the eight directions and four cardinal points. The Dai Meridian starts at Zhangmen acupoint below the hypochondrium, meeting the Foot Jueyin and Shaoyang meridians, level with Tianshu acupoint, like a heavenly belt crossing the waist. Knowing that the extraordinary vessels follow the regular meridians, if the regular meridians are treated, the extraordinary vessels are also treated; why speak deeply of treatment methods to display novelty and strangeness!