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。
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。故终有十五焉。
二十七难曰∶脉有奇经八脉者，不拘于十二经，何也？然∶有阳维，有阴维，有阳跷，有阴跷，有冲，
有督，有任，有带之脉。凡此八脉者，皆不拘于经，故曰奇经八脉也。
经有十二，络有十五，凡二十七气，相随上下，何独不拘于经也？然∶圣人图设沟渠，通
利水道，以备不然。天雨降下，沟渠溢满，当此之时， 霈妄作，圣人不能复图也。此络脉满溢，
诸经不能复拘也。
二十八难曰∶其奇经八脉者，既不拘于十二经，皆何起何继也？然∶督脉者，起于下极之俞，
并于脊里，上至风府，入属于脑。任脉者，起于中极之下，以上
毛际，循腹里，上关元，至喉咽。冲脉者，起于气冲，并足阳明之经，夹脐上行，至胸中而散
也。带脉者，起于季胁，回身一周。阳跷脉者，起于跟中，循外踝上行，入风池。阴跷脉者，亦
起于跟中，循内踝上行，至咽喉，交贯冲脉。阳维阴维者，维络于身，溢蓄不能环流灌溉诸经
者也。故阳维起于诸阳会也，阴维起于诸阴交也。比于圣人图设沟渠，沟渠满溢，流于深湖，故圣
人不能拘通也，而人脉隆盛，入于八脉而不环周，故十二经亦不能拘之，其受邪气，蓄则肿热，
砭射之也。
第二十五难说：人体有十二经脉，但五脏加六腑总共只有十一个脏腑，那么多出来的这一条经脉是哪一条呢？回答是：多出的这一条，是指手少阴心经与心包络（心主）的别行脉。心包络与三焦互为表里，它们都有名称而没有具体的形态实体，所以说经脉共有十二条。
第二十六难说：经脉有十二条，络脉有十五条，那剩下的三条络脉是什么络脉呢？回答是：有阳跷络、阴跷络和脾的大络。所谓阳络，就是阳跷脉的络脉；所谓阴络，就是阴跷脉的络脉。所以最终共有十五条络脉。
第二十七难说：脉象中有奇经八脉，它们不受十二正经的约束，这是为什么呢？回答是：有阳维脉、阴维脉、阳跷脉、阴跷脉、冲脉、督脉、任脉、带脉。这八条脉都不受十二正经的拘束，所以称为奇经八脉。
既然经脉有十二条，络脉有十五条，总共二十七气，上下相随运行，为什么唯独奇经八脉不受正经的约束呢？回答是：圣人规划设置沟渠，以疏通水道，以备不时之需。当天下大雨时，沟渠会溢满，此时如果暴雨大作，即使是圣人也不能再重新规划了。这就好比络脉满溢，诸条正经就不能再约束它了。
第二十八难说：那奇经八脉既然不受十二正经的约束，它们都是从哪里起始、到哪里接续的呢？回答是：督脉，起始于尾骨端的长强穴，并行于脊柱内部，向上至风府穴，进入并归属于脑。任脉，起始于中极穴下方，向上经过阴毛边缘，沿腹部内侧上行，经过关元穴，到达咽喉。冲脉，起始于气冲穴，伴行足阳明胃经，夹脐两侧上行，至胸部散开。带脉，起始于季胁部，环绕身体一周。阳跷脉，起始于足跟中部，沿外踝上行，进入风池穴。阴跷脉，也起始于足跟中部，沿内踝上行，到达咽喉，与冲脉相交贯通。阳维脉和阴维脉，维系联络全身，当气血满溢时不能环流灌溉各条正经。所以阳维脉起始于各阳经交会之处，阴维脉起始于各阴经交会之处。这就像圣人规划设置沟渠，沟渠满了，水流向深湖，所以圣人无法再强行约束它一样；人体的脉气隆盛，流入八脉而不循环周身，所以十二正经也不能约束它。这些脉受到邪气侵袭，蓄积则出现肿胀发热，需要用砭石刺破放血来治疗。
Difficulty 25 states: There are twelve meridians, yet there are only five zang organs and six fu organs, totaling eleven. Which meridian is the extra one? The answer is: The extra meridian refers to the divergent channel of the Hand-Shaoyin (Heart) and the Pericardium Master (Xin Zhu). The Pericardium Master and the Sanjiao (Triple Burner) form an interior-exterior relationship; both have names but no distinct physical form. Therefore, it is said that there are twelve meridians.
Difficulty 26 states: There are twelve meridians and fifteen collaterals. 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. The "Yin collateral" refers to the collateral of the Yin Qiao vessel. Thus, there are fifteen in total.
Difficulty 27 states: Among the pulses, there are the Eight Extraordinary Vessels, which are not restricted by the Twelve Regular Meridians. Why is this so? The answer is: There are the Yang Wei, Yin Wei, Yang Qiao, Yin Qiao, Chong, Du, Ren, and Dai vessels. All these eight vessels are not bound by the regular meridians, hence they are called the Eight Extraordinary Vessels.
Given that there are twelve meridians and fifteen collaterals, comprising twenty-seven qi pathways that follow each other up and down, why are the extraordinary vessels specifically not constrained by the regular meridians? The answer is: Sages dug canals to facilitate water flow, preparing for contingencies. When heavy rain falls and the canals overflow, even if torrential rains occur, the sages cannot redraw the channels. Similarly, when the collateral vessels become full and overflow, the regular meridians can no longer constrain them.
Difficulty 28 states: Since the Eight Extraordinary Vessels are not constrained by the Twelve Regular Meridians, where do they originate and where do they connect? The answer is: The Du Mai (Governing Vessel) originates at the Shu point of the lower extreme [Changqiang, GV1], runs parallel within the spinal column, ascends to the Fengfu point [GV16], and enters to reside in the brain. The Ren Mai (Conception Vessel) originates below the Zhongji point [CV3], ascends above the pubic hair line, follows the interior of the abdomen, passes through the Guanyuan point [CV4], and reaches the throat. The Chong Mai (Penetrating Vessel) originates at the Qichong point [ST30], runs alongside the Foot-Yangming Stomach Meridian, ascends flanking the navel, and disperses in the chest. The Dai Mai (Girdle Vessel) originates at the costal region and encircles the body once. The Yang Qiao Mai (Yang Heel Vessel) originates in the middle of the heel, ascends along the lateral malleolus, and enters the Fengchi point [GB20]. The Yin Qiao Mai (Yin Heel Vessel) also originates in the middle of the heel, ascends along the medial malleolus, reaches the throat, and intersects with the Chong Mai. The Yang Wei and Yin Wei vessels maintain and link the body; when qi and blood overflow, they cannot circulate and irrigate the regular meridians. Therefore, the Yang Wei originates from the meeting point of all yang meridians, and the Yin Wei originates from the intersection of all yin meridians. This is analogous to sages digging canals; when the canals overflow, water flows into deep lakes, and the sages cannot constrain it. Similarly, when human pulse qi becomes vigorous, it enters the eight extraordinary vessels without circulating continuously, so the twelve regular meridians cannot constrain it. When these vessels are affected by pathogenic factors and accumulation occurs, swelling and heat result, which should be treated by pricking with bi stones [to release blood].