十八难曰∶脉有三部，部有四经，手有太阴、阳明，足有太阳、少阴，为上下部，何谓也？
然∶手太阴、阳明，金也；足少阴、太阳，水也；金生水，水流下行而不能上，故在下部也。足
厥阴、少阳，木也；生手太阳、少阴火，火炎上行而不能下，故为上部。手心主、少阳火，生足太阴、
阳明土，土主中宫，故在中部也。此皆五行子母更相生养者也。
脉有三部九候，各何主之？然∶三部者，寸关尺也。九候者，浮中沉也。上部法天，主胸以上至
头之有疾也；中部法人，主膈以下至脐之有疾也；下部法地，主脐以下至足之有疾也。审而刺之者也。
人病有沉滞、久积聚，可切脉而知之耶？
然∶诊在右胁有积气，得肺脉结，脉结甚则积甚，结微则气微。
诊不得肺脉，而右胁有积气者何也？然∶肺脉虽不见，右手脉当沉伏。
其外痼疾同法耶？将异也？
然∶结者，脉来去时一止，无常数，名曰结也。伏者，脉行筋下也，浮者，脉在肉上行也。左右表里，
法皆如此。
假令脉结伏者，内无积聚；脉浮结者，外无痼疾；有积聚脉不结伏，有痼疾脉不浮结。为脉不应病
，病不应脉，是为死病也。
十九难曰∶经言脉有逆顺，男女有恒。而反者，何谓也？
然∶男子生于寅，寅为木，阳也。女子生于申，申为金，阴也。故男脉在关上，女脉在关下，是以
男子尺脉恒弱，女子尺脉恒盛，是其常也。
反者，男得女脉，女得男脉也。其为病何如？
然∶男得女脉为不足，病在内；左得之病在左，右得之病在右，随脉言之也。女得男脉为太过
，病在四肢；左得之病在左，右得之病在右，随脉言之，此之谓也。
第十八难说：脉诊分为三部，每部有四条经脉。手部有太阴经和阳明经，足部有太阳经和少阴经，这被称为上部和下部，这是为什么呢？
回答说：手太阴肺经和手阳明大肠经，五行属金；足少阴肾经和足太阳膀胱经，五行属水；金能生水，而水气向下流动而不能上行，所以归属于下部。足厥阴肝经和足少阳胆经，五行属木；木能生手太阳小肠经和手少阴心经的火，火性炎上而不能下行，所以归属于上部。手厥阴心包经和手少阳三焦经，五行属火；火能生足太阴脾经和足阳明胃经的土，土居中宫（中央），所以归属于中部。这些都是五行中子母相生、相互滋养的关系。
脉诊有三部九候，各自主管什么部位呢？回答说：三部是指寸、关、尺三个部位。九候是指浮取、中取、沉取三种指力。上部效法天，主管胸部以上至头部的疾病；中部效法人，主管膈肌以下至肚脐的疾病；下部效法地，主管肚脐以下至足部的疾病。医生需仔细审察后进行针刺治疗。
回答说：如果在右胁下诊察到有积气，且出现肺脉结象，脉结越严重则积聚越严重，脉结轻微则气滞轻微。
如果诊不到肺脉结象，但右胁下有积气，这是什么原因呢？回答说：虽然肺脉没有显现结象，但右手脉应当呈现沉伏之象。
这种外部的顽固性疾病也是同样的诊法吗？还是有所不同？
回答说：所谓“结”，是指脉搏在来去过程中偶尔停止一次，没有固定的规律，称为结脉。所谓“伏”，是指脉搏行于筋下深处。所谓“浮”，是指脉搏行于肌肉表层。左右表里的诊法都是如此。
假如脉象表现为结或伏，但体内并没有积聚之病；或者脉象表现为浮或结，但体外并没有顽固性疾病；如果有积聚之病脉象却不结伏，有顽固性疾病脉象却不浮结。这就是脉象与病情不相符，病情与脉象不相应，属于死证。
第十九难说：医经中说脉象有逆顺之分，男女脉象有常态。如果出现相反的情况，是什么意思呢？
回答说：男子生于寅月，寅属木，为阳气；女子生于申月，申属金，为阴气。所以男子的脉象多在关上（寸部），女子的脉象多在关下（尺部）。因此，男子的尺脉通常较弱，女子的尺脉通常旺盛，这是正常的规律。
所谓的“反”，是指男子出现了女子的脉象，女子出现了男子的脉象。他们患的是什么病呢？
回答说：男子出现女子的脉象（尺盛），表示正气不足，病在内脏；如果在左手出现，病在身体左侧；如果在右手出现，病在身体右侧，根据脉象所在来判断。女子出现男子的脉象（尺弱），表示邪气太过，病在四肢；如果在左手出现，病在身体左侧；如果在右手出现，病在身体右侧，根据脉象所在来判断，这就是所说的道理。
Chapter 18 states: The pulse is divided into three positions (Cun, Guan, Chi), and each position corresponds to four meridians. The hand has the Taiyin (Lung) and Yangming (Large Intestine) meridians; the foot has the Taiyang (Bladder) and Shaoyin (Kidney) meridians. These are referred to as the upper and lower parts. What is the reason for this?
The answer is: The Hand-Taiyin Lung Meridian and Hand-Yangming Large Intestine Meridian belong to Metal; the Foot-Shaoyin Kidney Meridian and Foot-Taiyang Bladder Meridian belong to Water. Metal generates Water, and water flows downward and cannot ascend; therefore, they are located in the lower part. The Foot-Jueyin Liver Meridian and Foot-Shaoyang Gallbladder Meridian belong to Wood; Wood generates the Fire of the Hand-Taiyang Small Intestine Meridian and Hand-Shaoyin Heart Meridian. Fire flares upward and cannot descend; therefore, they constitute the upper part. The Hand-Jueyin Pericardium Meridian and Hand-Shaoyang Sanjiao (Triple Burner) Meridian belong to Fire; Fire generates the Earth of the Foot-Taiyin Spleen Meridian and Foot-Yangming Stomach Meridian. Earth governs the Central Palace (Middle Jiao); therefore, they are in the middle part. These all illustrate the mutual generation and nourishment between mother and child elements within the Five Phases (Wu Xing).
Regarding the three positions and nine inspections (Fu, Zhong, Chen) of the pulse, what does each primarily indicate? The answer is: The three positions refer to Cun (Inch), Guan (Bar), and Chi (Cubit). The nine inspections refer to superficial (Floating), moderate (Medium), and deep (Sinking) palpation. The upper position models Heaven and indicates diseases from the chest up to the head; the middle position models Humanity and indicates diseases from below the diaphragm to the umbilicus; the lower position models Earth and indicates diseases from below the umbilicus to the feet. One must examine them carefully before applying acupuncture.
Can one know if a patient suffers from stagnant conditions or long-standing accumulations through pulse diagnosis?
The answer is: If there is an accumulation of Qi in the right hypochondrium, and a Jie (Knotted) pulse of the Lung meridian is obtained, the more severe the knottedness, the greater the accumulation; the slight the knottedness, the lesser the Qi stagnation.
What if the Lung pulse does not show a Jie pattern, yet there is an accumulation of Qi in the right hypochondrium? The answer is: Although the Lung pulse does not appear knotted, the pulse on the right hand should be Fu (Deep/Hidden).
Is the method for external chronic illnesses the same? Or is it different?
The answer is: "Jie" refers to a pulse that stops occasionally during its coming and going, without a fixed number, known as a Knotted pulse. "Fu" means the pulse travels beneath the tendons (deep). "Fu" (Floating) means the pulse travels above the flesh (superficial). The principles for left/right and interior/exterior are applied similarly.
If the pulse is Jie or Fu, but there is no internal accumulation; or if the pulse is Floating or Jie, but there is no external chronic disease; if there is an accumulation but the pulse is not Jie or Fu, or if there is a chronic disease but the pulse is not Floating or Jie—this constitutes a mismatch between pulse and disease, and disease and pulse, which indicates a fatal condition.
Chapter 19 states: The classics mention that pulses have contrary and compliant patterns, and men and women have constant norms. What does it mean when these are reversed?
The answer is: Men are associated with Yin month, where Yin represents Wood and Yang energy. Women are associated with Shen month, where Shen represents Metal and Yin energy. Therefore, in men, the pulse is prominent at the Guan position (upper/middle), while in women, it is prominent at the Chi position (lower). Thus, the Chi pulse in men is typically weak, while the Chi pulse in women is typically strong; this is the normal state.
Reversal refers to men obtaining women's pulse characteristics, and women obtaining men's pulse characteristics. What kind of illness do they suffer?
The answer is: When a man obtains a woman's pulse (strong Chi), it indicates deficiency, with disease located internally. If found on the left, the disease is on the left side; if on the right, the disease is on the right side, determined by following the pulse location. When a woman obtains a man's pulse (weak Chi), it indicates excess, with disease located in the four limbs. If found on the left, the disease is on the left side; if on the right, the disease is on the right side, determined by following the pulse location. This is what is meant.