按《内经》谓∶寸口主中，（寸口为太阴肺经脉，肺为脏，故以此通候五脏之气。）人迎主
外。（阳明胃经脉也，胃为腑，故以此通候六腑之气。腑阳脏阴，阳外阴内，故寸口以候内，人迎以候外。）人迎
本在颈下，夹结喉旁一寸五分，后世既废古人三部分诊之法，遂改候人迎于左手关
脉，而名右手关脉为气口，与之相衡。谓气口大于人迎，为内伤饮食，（以右关属胃也。
此有理。）人迎大于气口，为外感风寒，（以左关属肝，肝主风也。然内风与外风无涉，于理未的。）分主
表里。虽与经意无异，而部位不同矣。犹之足少阴肾气，本于太溪诊之，（在足内踝后
五分，筋骨上动脉陷中。）今则诊于两尺。足阳明胃气，本于跗阳（即冲阳，在足跗上，
去陷谷二寸，高骨间动脉中。）诊之，今则诊于右关也。（张仲景每以寸口、跗阳、肾少阴并言，喻嘉
言谓即寸关尺。）
再按结喉旁人迎脉，怕大于两手寸口脉数倍，从无寸口反大于人迎者。（经谓平人
春夏人迎微大，秋来气口为大，恐非。）此后人所以改候人迎于左关，以与右关较大小也。
古谓男脉左大于右，女脉右大于左，验之不然。盖人之右手，比左手略大，脉
亦应之而右大于左，不论男女皆然也。惟男两尺怕虚，女两尺怕实，差不同耳。
据《内经》记载：寸口脉主要反映内脏情况，（寸口是手太阴肺经的脉搏处，肺属于脏，因此用它来全面诊察五脏的气机。）人迎脉主要反映体表及六腑情况。（人迎是足阳明胃经的脉搏处，胃属于腑，因此用它来全面诊察六腑的气机。腑属阳、脏属阴，阳主外、阴主内，所以寸口用来候察内部，人迎用来候察外部。）人迎脉原本位于颈部下方，喉结旁开一寸五分处。后世废弃了古人“三部”分别诊察的方法，于是改为在左手关脉处诊察人迎，而将右手关脉命名为气口，以此二者进行对比衡量。认为气口脉大于人迎脉，是内伤饮食所致，（因为右关脉对应胃。这有一定道理。）人迎脉大于气口脉，是外感风寒所致，（因为左关脉对应肝，肝主风。然而内风与外风并无关联，这在理论上并不确切。）以此区分表证和里证。虽然这与经典原意没有太大差异，但诊察的部位却不同了。这就好比足少阴肾气，原本应在太溪穴处诊察，（太溪穴位于足内踝后方五分处，筋骨之间的动脉凹陷中。）现在则诊察两尺脉。足阳明胃气，原本应在跗阳穴（即冲阳穴，位于足背上方，距陷谷穴二寸，高骨间的动脉搏动处。）处诊察，现在则诊察右关脉。（张仲景常常将寸口、跗阳、肾少阴并提，喻嘉言认为指的就是寸、关、尺三部脉。）
再考察，喉结旁的人迎脉，恐怕比两手寸口脉的搏动大数倍，从来没有出现寸口脉反而大于人迎脉的情况。（经文说正常人在春夏季节人迎脉微大，秋季气口脉大，恐怕并非如此。）这就是后人之所以改在左关脉处诊察人迎，以便与右关脉比较大小原因所在。
古时候说男子脉象左大于右，女子脉象右大于左，验证起来并非如此。大概人的右手比左手略大，脉象也相应地右大于左，不论男女都是这样。只是男子两尺脉怕虚弱，女子两尺脉怕实盛，仅此不同罢了。
According to the *Neijing* (Classic of Internal Canon): The Cun Kou pulse primarily reflects internal conditions. (Cun Kou is the pulse site of the Hand-Taiyin Lung Meridian; as the Lung is a Zang organ, it is used to comprehensively assess the Qi of the five Zang organs.) The Ying Shou pulse primarily reflects external conditions. (Ying Shou is the pulse site of the Foot-Yangming Stomach Meridian; as the Stomach is a Fu organ, it is used to comprehensively assess the Qi of the six Fu organs. Fu organs are Yang and Zang organs are Yin; Yang governs the exterior and Yin governs the interior; thus, Cun Kou is used to inspect the interior, and Ying Shou is used to inspect the exterior.) The Ying Shou pulse originally located below the neck, one inch and five fen lateral to the Adam's apple. Later generations abandoned the ancient method of "three-part" separate diagnosis, and instead changed to palpating the Ying Shou at the Guan position of the left wrist, naming the Guan position of the right wrist as Qi Kou, using them for comparative assessment. It was believed that if the Qi Kou pulse is larger than the Ying Shou pulse, it indicates internal injury due to diet. (Since the Right Guan corresponds to the Stomach. This has some rationale.) If the Ying Shou pulse is larger than the Qi Kou pulse, it indicates external contraction of wind-cold. (Since the Left Guan corresponds to the Liver, and the Liver governs wind. However, internal wind and external wind are unrelated, so this theory is not precise.) This distinguishes between exterior and interior syndromes. Although this differs little from the original intent of the classics, the diagnostic locations are different. This is similar to how the Qi of the Foot-Shaoyin Kidney was originally diagnosed at Tai Xi. (Tai Xi is located five fen posterior to the medial malleolus, in the depression of the arterial pulsation between the bone and tendon.) Now, it is diagnosed at both Chi positions. The Qi of the Foot-Yangming Stomach was originally diagnosed at Fu Yang (i.e., Chong Yang, located on the dorsum of the foot, two cun distal to Xian Gu, in the arterial pulsation between the high bones.) Now, it is diagnosed at the Right Guan. (Zhang Zhongjing often mentioned Cun Kou, Fu Yang, and Kidney-Shaoyin together; Yu Jiayan stated that these refer to the Cun, Guan, and Chi positions.)
Furthermore, regarding the Ying Shou pulse beside the Adam's apple, its pulsation is likely several times stronger than the Cun Kou pulses of both hands; there is never a case where the Cun Kou pulse is larger than the Ying Shou pulse. (The classic states that in healthy individuals, the Ying Shou is slightly larger in spring and summer, while the Qi Kou is larger in autumn; this may not be accurate.) This is why later practitioners changed to diagnosing Ying Shou at the Left Guan, to compare its size with the Right Guan.
Ancient texts stated that men's pulses are larger on the left than the right, and women's pulses are larger on the right than the left. Verification shows this is not true. Generally, a person's right hand is slightly larger than the left, and the pulse accordingly is larger on the right than the left, regardless of gender. The only difference is that men's Chi pulses should not be deficient, while women's Chi pulses should not be excess; this is the sole distinction.