凡人两手两足，各有三阴脉、三阳脉，以合为十二经也。三阴为太阴、少阴、厥阴，三
阳为太阳、阳明、少阳也。人两手足各有三阴三阳脉，相合为十二经也。谓之经者，以气血流行
经常不息而言；谓之脉者，以血理分衮行体而言也。
手之三阴，从脏走至手；手之三阳，从手走至头。足之三阳，从头下走至足；足之三阴
，从足上走至腹。
手三阴从脏走至手。谓手太阴起中焦，至出大指之端；手少阴起心中，至出小指之端；
手厥阴起胸中，至出中指之端。
三阳从手走至头。谓手阳明起大指次指之端，至上挟鼻孔；手太阳起小指之端，至目内
；手少阳起小指次指之端，至目锐 。
足三阴从足走入腹。谓足太阴起大指之端，至属脾络胃；足少阴起足心，至属肾络膀胱
；足厥阴起大指聚毛，至属肝络胆。足三阴虽曰从足入腹，然太阴乃复上膈挟咽，散舌本下；少
阴乃复从肾上挟舌本；厥阴乃复上出额，与督脉会于巅。
盖手太阴从肺系横出腋下，手少阴从心系上肺出腋下，手厥阴循胁上抵腋下。此秦越人
所谓诸阴脉皆至颈胸而还者也，而厥阴则又上出于巅。盖厥阴，阴之尽也。所以然者，示阴无可尽
之理，亦从《易》之硕果不食，示阳无可尽之理义也。然《易》之阴阳以气言，人身之阴阳
以脏象言。言气则无形，而脏象有质，气阳而质阴也。然则无形者贵乎阳，有质者贵乎阴欤
凡是人的双手和双足，各自拥有三条阴脉和三阳脉，相互结合构成十二经脉。三阴经包括太阴、少阴、厥阴，三阳经包括太阳、阳明、少阳。人的双手和双足各有三条阴脉和三阳脉，相互结合形成十二经脉。称为“经”，是因为气血在其中流行运行而不停息；称为“脉”，是因为血液的纹理分布并运行于形体之中。
手部的三条阴经，从内脏走向手部；手部的三条阳经，从手部走向头部。足部的三条阳经，从头部向下走向足部；足部的三条阴经，从足部向上走向腹部。
手部的三条阴经从内脏走向手部。具体而言：手太阴肺经起始于中焦（脾胃所在区域），终止于大拇指的末端；手少阴心经起始于心，终止于小指的末端；手厥阴心包经起始于胸中，终止于中指的末端。
手部的三条阳经从手部走向头部。具体而言：手阳明大肠经起始于食指与大拇指相邻的一侧末端，上行至鼻翼旁挟持鼻孔处；手太阳小肠经起始于小指末端，上行至目内眦（眼角内侧）；手少阳三焦经起始于无名指与小指相邻的一侧末端，上行至目外眦（眼角外侧）。
足部的三条阴经从足部走入腹部。具体而言：足太阴脾经起始于大拇指的末端，上行归属于脾并联络胃；足少阴肾经起始于足心，上行归属于肾并联络膀胱；足厥阴肝经起始于大拇指丛毛处，上行归属于肝并联络胆。足部的三条阴经虽然说是从足部进入腹部，但足太阴脾经还会再次上行穿过膈肌，挟持咽喉，散布于舌根下方；足少阴肾经还会再次从肾脏上行挟持舌根；足厥阴肝经还会再次上行出于额部，与督脉交会于头顶。
大致来说，手太阴肺经从肺系（气管及喉咙等组织）横向走出腋下；手少阴心经从心系（心脏与其他脏器相连的组织）上行经过肺脏后走出腋下；手厥阴心包经沿着胁肋上行抵达腋下。这就是秦越人（扁鹊）所说的所有阴脉都到达颈部和胸部便返回的说法，而厥阴经则又上行出于头顶。大概因为厥阴是阴气的尽头。之所以这样，是为了显示阴气没有真正穷尽的道理，也体现了《易经》中“硕果不食”所显示的阳气没有穷尽的道理义理。然而，《易经》中的阴阳是从“气”的角度来说的，人身上的阴阳是从“脏象”（脏腑的外在表现）角度来说的。谈论气则是无形的，而脏象是有形的实体，气属阳而形质属阴。那么，无形的事物是否更崇尚阳，有形的物质是否更崇尚阴呢？
In every person, the two hands and two feet each possess three Yin meridians and three Yang meridians, which combine to form the Twelve Primary Meridians. The Three Yin meridians are Taiyin (Greater Yin), Shaoyin (Lesser Yin), and Jueyin (Terminal Yin); the Three Yang meridians are Taiyang (Greater Yang), Yangming (Yang Brightness), and Shaoyang (Lesser Yang). The three Yin and three Yang meridians in each hand and foot combine to constitute the Twelve Primary Meridians. They are called "Meridians" (Jing) because Qi and Blood flow through them continuously without cessation; they are called "Vessels" (Mai) because they represent the channels through which blood distributes and circulates throughout the body.
The Three Yin meridians of the hands travel from the Zang organs to the hands; the Three Yang meridians of the hands travel from the hands to the head. The Three Yang meridians of the feet travel from the head down to the feet; the Three Yin meridians of the feet travel from the feet up to the abdomen.
The Three Yin meridians of the hands originate from the Zang organs and proceed to the hands. Specifically: Hand-Taiyin Lung Meridian originates from the Middle Jiao (the region of the Spleen and Stomach) and terminates at the tip of the thumb; Hand-Shaoyin Heart Meridian originates from the Heart and terminates at the tip of the little finger; Hand-Jueyin Pericardium Meridian originates from the Chest and terminates at the tip of the middle finger.
The Three Yang meridians of the hands travel from the hands to the head. Specifically: Hand-Yangming Large Intestine Meridian originates at the radial side of the index finger (adjacent to the thumb) and ascends to flank the nostrils; Hand-Taiyang Small Intestine Meridian originates at the tip of the little finger and ascends to the inner canthus of the eye; Hand-Shaoyang Sanjiao Meridian originates at the ulnar side of the ring finger (adjacent to the little finger) and ascends to the outer canthus of the eye.
The Three Yin meridians of the feet enter the abdomen from the feet. Specifically: Foot-Taiyin Spleen Meridian originates at the tip of the big toe, ascends to connect with the Spleen and link to the Stomach; Foot-Shaoyin Kidney Meridian originates at the sole of the foot, ascends to connect with the Kidney and link to the Bladder; Foot-Jueyin Liver Meridian originates at the hair cluster on the big toe, ascends to connect with the Liver and link to the Gallbladder. Although the Three Yin meridians of the feet are said to enter the abdomen from the feet, Foot-Taiyin Spleen Meridian further ascends through the diaphragm, flanks the pharynx, and disperses below the root of the tongue; Foot-Shaoyin Kidney Meridian further ascends from the Kidney to flank the root of the tongue; Foot-Jueyin Liver Meridian further ascends to emerge from the forehead and meets the Du Vessel (Governing Vessel) at the vertex of the head.
Generally speaking, Hand-Taiyin Lung Meridian emerges horizontally from the Lung system (trachea and throat tissues) into the axilla; Hand-Shaoyin Heart Meridian ascends from the Heart system through the Lungs and emerges into the axilla; Hand-Jueyin Pericardium Meridian follows the hypochondrium upward to reach the axilla. This is what Qin Yue-ren (Bian Que) referred to when stating that all Yin meridians reach the neck and chest before returning, whereas the Jueyin meridian further ascends to emerge at the vertex. This is because Jueyin represents the extremity of Yin. The reason for this is to demonstrate the principle that Yin has no true end, mirroring the concept in the *I Ching* (Book of Changes) of "unconsumed fruit," which illustrates that Yang also has no end. However, the Yin and Yang in the *I Ching* are discussed in terms of Qi, while Yin and Yang in the human body are discussed in terms of Zang-Xiang (visceral manifestations). Qi is formless, whereas Zang-Xiang have physical substance; Qi is Yang, and substance is Yin. Therefore, does the formless favor Yang, and the substantial favor Yin?