二十五难曰。有十二经。五脏六腑。十一耳。其一经者。何等经也。然。一经者、手少阴与心主别脉也。心主与三
焦为表里。俱有名而无形。故言经有十二也。
丁曰。言少阴与心主别脉者。谓心与小肠为表里。心主与三焦为表里也。少阴是真心脉。为君火。心主者。共三焦
相火。故别也。相行君命。故有心名无位也。杨曰。手少阴。真心脉也。手心主。心包络脉也。二脉俱是心脉。而少阴
与小肠合。心主与三焦脉合。三焦有位而无形。心主有名而无脏。故二经为表里也。五脏六腑各一脉为十一脉。心有两
脉。合成十二经焉。据此而言。六腑亦止五腑耳。虞曰。心主者、手厥阴脉也。三焦者、手少阳脉也。二经合为表里。
乃合为十二经也。手厥阴心包络脉者。起于胸中。出属心包。下膈。历络三焦。其支者。循胸中。出胁下腋三寸。上抵
腋下。下循 内。行太阴少阴之间。入肘中。下臂行两筋之间。入掌中。出中指之端。准此推之。心包外有经脉。出于
中指。内相维络于三焦。归于少阴之经。配手厥阴之脉。手少阳脉者。出于手小指次指之端。上出次指之间。循手表腕。
出臂外两骨之间。上贯肘。循 外上肩。交出足少阳之后。入缺盆布膻中。散络心包。下膈。循属三焦。准此推寻。乃
与心包更相维络。三焦配手少阳。心包配手厥阴。二经俱外有流行经脉。内无脏腑。故配之为表里。诸家脉惟言命门与
三焦为表里。在右手尺中。惟此经言。则三焦与心主为表里也。又左寸火。右寸金。左关木。右关土。左尺水。右尺火。
左尺男。右尺女。可验之。经有夫妇对位。若三焦配命门为表里。则水火同位也。
二十六难曰。经有十二。络有十五。余三络者、是何等络也。然。有阳络。有阴络。有脾之大络。阳络者、阳跷之
络也。阴络者、阴跷之络也。故络有十五焉。
丁曰。十二经十五络者。谓每一经各有一络。其肝、心、肾。经在左即络右。其脾、肺、心包。经在右即络左。其
阳跷。经在左足外踝。络在右足外踝。其阴跷。经在右足内踝。络在左足内踝。此者是阴跷阳跷之络也。脾之大络者。
脾象土。主中宫。王四季。分养四脏。故曰脾之大络。是名大包穴。在渊液下三寸。布胸中。出九肋间是也。杨曰。十
二经各有一络。为十二络耳。今云十五络者。有阴阳之二络。脾之大络。合为十五络也。人有阴阳两跷。在两足内外。
男子以足外者为经。足内者为络。女子以足内者为经。足外者为络。故有阴阳跷二络也。经云。男子数其阳。女子数其
阴。当数者为经。不当数者为络。此之谓也。脾之大络。名曰大包。此则脾有二络也。凡经脉为里。（按为下原衍表字。
根据灵枢脉度篇删。）支而横者为络。络之别者为孙也。
第二十五难说：人体有十二经脉，但五脏加六腑只有十一个。多出来的这一条经脉，是哪一条呢？回答是：多出的这一条，是手少阴心经与手厥阴心包经（心主）各自独立的脉络。心包与三焦互为表里，二者都只有名称而没有具体的实体脏器形态，所以说经脉共有十二条。
丁氏说：所谓手少阴与心包是独立的脉络，是因为心与小肠互为表里，心包与三焦互为表里。手少阴是真心之脉，属于君火；心包则与三焦的相火相应，所以它是独立的。它奉行君主的命令而行事，因此有心之名而无独立之位。
杨氏说：手少阴是真心之脉，手心主（即手厥阴）是心包络之脉。这两条脉都属于心脉系统，但手少阴与小肠相合，手厥阴与三焦相合。三焦有位置但没有具体形态，心包有名称但没有独立的脏体，所以说这两条经脉互为表里。五脏各有一条脉，六腑中除三焦外有五条脉，共十一条脉。因为心脏有两条脉（手少阴和手厥阴），合起来就是十二条经脉。据此而言，六腑实际上只算五个（因为三焦无形）。
虞氏说：心主即是手厥阴脉，三焦即是手少阳脉。这两条经脉合起来构成表里关系，从而凑成十二经脉。手厥阴心包络脉，起始于胸中，向下归属于心包，穿过膈肌，依次联络上、中、下三焦。其分支，沿着胸中走出，经过胁下腋下三寸处，向上到达腋下，向下沿手臂内侧，行走在手太阴肺经和手少阴心经之间，进入肘窝中，再向下沿前臂两筋之间行走，进入手掌中心，出于中指末端。根据这些循行路线推断，心包外侧有经脉流行，出于中指，内侧相互维系联络于三焦，回归到手少阴经，配属于手厥阴脉。手少阳脉，出于手小指和无名指之间的末端，向上出于无名指之间，沿手腕背侧，走出前臂外侧两骨之间，向上贯穿肘部，沿上臂外侧上行至肩，交叉到足少阳胆经之后，进入缺盆，分布于膻中，散络于心包，向下穿过膈肌，归属于三焦。根据这些线索推寻，它与心包相互维系联络。三焦配属手少阳，心包配属手厥阴，这两条经脉外部都有流行的经脉，内部却没有脏腑实体，所以配合为表里。各家脉学只说命门与三焦互为表里，位于右手尺部。唯独这部经典说三焦与心包互为表里。另外，左寸属火，右寸属金，左关属木，右关属土，左尺属水，右尺属火。左尺对应男性，右尺对应女性，可以验证这一点。经脉有夫妇对位的关系。如果三焦配命门为表里，那么水和火就会处于同一位置（违背阴阳对立原则）。
第二十六难说：经脉有十二条，络脉有十五条。剩下的三条络脉，是什么络脉呢？回答是：有阳跷络，有阴跷络，还有脾的大络。阳络是指阳跷脉的络脉，阴络是指阴跷脉的络脉。所以络脉共有十五条。
丁氏说：十二经十五条络，是指每一条经脉各有一条络脉。其中肝、心、肾的经脉在左侧，其络脉却在右侧；脾、肺、心包的经脉在右侧，其络脉却在左侧。阳跷脉的经脉在左脚外踝，其络脉在右脚外踝；阴跷脉的经脉在右脚内踝，其络脉在左脚内踝。这就是阴跷和阳跷的络脉。脾的大络，因为脾象征土，主宰中宫，旺于四季，分养四脏，所以称为脾的大络，名叫大包穴，位于渊液穴下方三寸，散布于胸中，出于第九肋骨之间。
杨氏说：十二经脉各有一条络脉，共十二条络脉。现在说十五条络脉，是因为加上阴阳两条跷脉的络脉，以及脾的大络，合起来共十五条。人有阴阳两条跷脉，位于双脚内外侧。男子以足外侧的为经，足内侧的为络；女子以足内侧的为经，足外侧的为络。所以有阴阳跷两条络脉。经书说：“男子数其阳，女子数其阴”，应当计算的那条作为经，不应当计算的那条作为络，说的就是这个道理。脾的大络名叫大包，这样脾就有两条络脉了。凡是经脉深入体内称为“里”（按：原文此处原有衍文“表”字，根据《灵枢·脉度》篇删除）。分支而横向走行的称为络，络的细小分支称为孙络。
Difficulty 25 states: There are twelve primary meridians. The five zang organs and six fu organs total eleven. Which meridian constitutes the extra one? The answer is: The extra meridian refers to the independent channels of the Hand-Shaoyin (Heart) and the Hand-Jueyin (Pericardium, also known as Xin Zhu). The Pericardium and the Sanjiao (Triple Burner) form an interior-exterior relationship; both possess names but lack distinct physical forms. Therefore, it is said that there are twelve meridians.
Ding stated: To say that Shaoyin and the Pericardium have independent channels means that the Heart and Small Intestine form an interior-exterior pair, while the Pericardium and the Sanjiao form an interior-exterior pair. Shaoyin is the true Heart channel, belonging to Minister Fire (Jun Huo). The Pericardium corresponds with the Minister Fire (Xiang Huo) of the Sanjiao, hence its independence. It executes the commands of the Sovereign (Monarch), thus having the name of the Heart but no independent position.
Yang stated: The Hand-Shaoyin is the channel of the true Heart. The Hand-Xin Zhu (Pericardium) is the channel of the Pericardium Bao Luo. Both channels belong to the Heart system, yet Shaoyin combines with the Small Intestine, while the Pericardium combines with the Sanjiao. The Sanjiao has a location but no form; the Pericardium has a name but no distinct organ. Thus, these two meridians form an interior-exterior relationship. Each of the five zang organs has one channel, and among the six fu organs, excluding the Sanjiao, there are five channels, totaling eleven channels. Since the Heart has two channels (Hand-Shaoyin and Hand-Jueyin), they combine to make twelve primary meridians. Based on this, the six fu organs effectively count as only five.
Yu stated: The Xin Zhu is the Hand-Jueyin channel, and the Sanjiao is the Hand-Shaoyang channel. These two meridians combine to form an interior-exterior relationship, thereby completing the twelve meridians. The Hand-Jueyin Pericardium Bao Luo channel originates in the chest, descends to connect with the Pericardium, passes through the diaphragm, and sequentially connects with the Upper, Middle, and Lower Sanjiao. Its branch travels along the chest, emerges from the lateral aspect of the hypochondrium three cun below the axilla, ascends to reach the axilla, and then descends along the medial aspect of the arm, running between the Taiyin and Shaoyin meridians, entering the elbow fossa, descending along the forearm between two tendons, entering the center of the palm, and emerging at the tip of the middle finger. Inferring from this, the Pericardium has external circulating meridians emerging at the middle finger, internally connected to the Sanjiao, returning to the Shaoyin meridian, and paired with the Jueyin meridian. The Hand-Shaoyang channel emerges at the tip of the space between the little and ring fingers, ascends between the ring and index fingers, follows the dorsal wrist, emerges between the two bones of the forearm, ascends through the elbow, follows the lateral aspect of the upper arm to the shoulder, crosses behind the Foot-Shaoyang meridian, enters the supraclavicular fossa, distributes in the Tan Zhong region, scatters and connects with the Pericardium, descends through the diaphragm, and connects with the Sanjiao. Tracing these paths, it interconnects with the Pericardium. The Sanjiao pairs with the Hand-Shaoyang, and the Pericardium pairs with the Hand-Jueyin. Both meridians have external circulating pathways but lack internal zang-fu organs, so they are paired as interior-exterior. Most pulse texts state that the Ming Men (Gate of Life) and the Sanjiao form an interior-exterior relationship, located at the right Chi position. Only this classic states that the Sanjiao and the Pericardium form an interior-exterior relationship. Furthermore, the left Cun belongs to Fire, the right Cun to Metal, the left Guan to Wood, the right Guan to Earth, the left Chi to Water, and the right Chi to Fire. The left Chi corresponds to males, and the right Chi to females, which can be verified. Meridians have husband-wife positional correspondences. If the Sanjiao were paired with the Ming Men as interior-exterior, Water and Fire would occupy the same position.
Difficulty 26 states: There are twelve primary meridians and fifteen collateral vessels. What are the remaining three collaterals? The answer is: There are the Yang Qiao collateral, the Yin Qiao collateral, and the large collateral of the Spleen. The Yang collateral refers to the collateral of the Yang Qiao vessel, and the Yin collateral refers to the collateral of the Yin Qiao vessel. Thus, there are fifteen collaterals in total.
Ding stated: Regarding the twelve meridians and fifteen collaterals, each of the twelve primary meridians has one collateral. For the Liver, Heart, and Kidney, if the meridian is on the left, the collateral is on the right. For the Spleen, Lung, and Pericardium, if the meridian is on the right, the collateral is on the left. For the Yang Qiao, the meridian is at the lateral malleolus of the left foot, and the collateral is at the lateral malleolus of the right foot. For the Yin Qiao, the meridian is at the medial malleolus of the right foot, and the collateral is at the medial malleolus of the left foot. These are the collaterals of the Yin and Yang Qiao vessels. The large collateral of the Spleen, because the Spleen symbolizes Earth, governs the Central Palace, prospers during the four seasons, and nourishes the four zang organs, is called the large collateral of the Spleen, named Da Bao acupoint. It is located three cun below Yuan Ye, spreads across the chest, and emerges between the ninth ribs.
Yang stated: Each of the twelve primary meridians has one collateral, totaling twelve collaterals. The statement of fifteen collaterals includes the two collaterals of the Yin and Yang Qiao vessels and the large collateral of the Spleen, summing to fifteen. Humans have Yin and Yang Qiao vessels located at the inner and outer sides of the feet. In males, the lateral foot vessel is the meridian, and the medial foot vessel is the collateral. In females, the medial foot vessel is the meridian, and the lateral foot vessel is the collateral. Hence, there are two collaterals from the Yin and Yang Qiao vessels. The classics state: "For males, count the Yang; for females, count the Yin." That which is counted serves as the meridian, and that which is not counted serves as the collateral. This is what is meant. The large collateral of the Spleen is named Da Bao, meaning the Spleen has two collaterals. Generally, primary meridians run deeply within (Li). [Note: The character 'Biao' was originally present here as a scribal error and has been deleted according to the *Ling Shu: Mai Du* chapter.] Branches that run transversely are called collaterals, and the finer branches of collaterals are called Sun collaterals.