尝考内经。阳气起于足五趾之表。阴气起于足五趾之里。足之三阳。从头至足。足之三阴。从足走腹。阳行
于外。阴行于内。阳则自上而下。阴则自下而上。析而言之。左为阳。右为阴。上为阳。下为阴。足之在外者为
阳。在内者为阴。自臀至膝。曰髀。自膝至踝。曰胫。踝下谓之跗。跗前谓之趾。其大趾。则少阳、阳明、厥阴、太阴
之所行。其次趾、中趾。则阳明之所行。其次于小趾之次趾。则少阳之所行。其小趾。则太阳。少阴之所行。此
皆经络之辨。部位之分也。望之之法。可弗深究其形容哉。以形言。则形盛为有余。形瘦为不足。胫肿跗肿
者。水气之实。胫枯脚小者。脾胃之虚。胫有大小者。肾壅偏枯。股无生肉者。脾虚气竭。足下平满者。伤肾之
绝征。脚底先穿者。疠风之败证。十指堕落者。筋死。十趾不用者。经病。两腿消瘦。曰肾消。独膝肿大。曰鹤膝。
足肿至踝。曰阳虚气结。脚肿上胫。曰香港脚逆冲。身体羸瘦。独足肿大者。营卫俱微。足趺壅肿。两膝如斗者。
胃气欲绝。此皆以形言也。以容言。则屈者为阴。伸者为阳。强者邪气实。痿者形气虚。拘急者。寒邪。纵缓者。
热疾。螈 者。筋脉相引。振掉者。血气俱虚。屈伸不能者。筋将惫。屈伸不利者。肾已亏。屈而不伸者。病在筋。
伸而不屈者。病在骨。阴缓而阳急者。阳跷病。阳缓而阴急者。阴跷病。跌蹶能前不能却者。太阳经之伤。
跛或左而或右者。风寒湿之病。转筋者。寒邪在筋。掣节者。寒邪在节。足纵而不任地者。大经空虚。足摇而
不任身者。骨髓枯减。足不收者。脾气虚。足不举者。脾气实。扬手掷足者。烦燥。逾垣上屋者。怒狂。筋缓不能
行者。肝劳。弃衣而狂走者。胃实。立不能坐。坐不能起者。阴阳交合。阴阳俱病也。此皆以容言也。合形容而
视之。审经络而辨之。验其足之寒温。切其脉之动静。参以四诊。究其三因。而病症之变。标本之殊。亦可知
其大略矣。
I have examined the *Neijing* (Inner Canon). Yang Qi originates at the exterior of the five toes of the foot, and Yin Qi originates at the interior of the five toes of the foot. The three Yang meridians of the foot run from the head to the foot; the three Yin meridians of the foot run from the foot to the abdomen. Yang moves on the exterior, and Yin moves on the interior. Yang moves from top to bottom, and Yin moves from bottom to top. Analyzing further: the left is Yang, the right is Yin; the upper is Yang, the lower is Yin. The lateral aspect of the foot is Yang, and the medial aspect is Yin. From the buttocks to the knee is called "Bi" (thigh); from the knee to the ankle is called "Jing" (shin/calf); below the ankle is called "Fu" (dorsum of foot); anterior to the dorsum is called "Zhi" (toe). Among these, the big toe is traversed by Shaoyang, Yangming, Jueyin, and Taiyin meridians; the second and middle toes are traversed by the Yangming meridian; the toe adjacent to the little toe is traversed by the Shaoyang meridian; the little toe is traversed by the Taiyang and Shaoyin meridians. These are distinctions of meridians and divisions of locations. In the method of observation, can one fail to deeply investigate their descriptions? Speaking of form: robust form indicates excess; emaciated form indicates deficiency. Swelling of the shin and dorsum indicates excess of water qi; withered shins and small feet indicate deficiency of Spleen and Stomach. Shins of unequal size indicate Kidney obstruction or hemiplegia; thighs without flesh indicate Spleen Qi deficiency and exhaustion. A flat and full sole indicates a sign of fatal Kidney injury; perforation starting from the sole indicates a deteriorating stage of Leprosy (Lifeng); falling off of ten toes indicates death of tendons; inactivity of ten toes indicates disease of the meridians; emaciation of both legs is called "Kidney Xiao" (diabetes-like wasting); isolated swelling of the knees is called "Crane Knee"; swelling of the foot extending to the ankle is called Yang deficiency with Qi stagnation; swelling of the foot ascending to the shin is called Hongxiangjiao counter-flowing attack; emaciation of the body with isolated swelling of the feet indicates deficiency of both Ying and Wei; swelling of the dorsum with knees protruding like bowls indicates impending extinction of Stomach Qi. These are all based on form. Speaking of posture: flexion is Yin, extension is Yang; rigidity indicates excess of pathogenic factors; flaccidity indicates deficiency of form and Qi; spasm and tension indicate Cold pathogen; laxity indicates Heat disease; convulsive traction indicates pulling of tendons and vessels; tremor and shaking indicate deficiency of both Blood and Qi; inability to flex or extend indicates impending exhaustion of tendons; difficulty in flexion and extension indicates deficiency of the Kidney; inability to extend after flexion indicates disease in the tendons; inability to flex after extension indicates disease in the bones; laxity on the medial side and tension on the lateral side indicates disease of the Yang Qiao vessel; laxity on the lateral side and tension on the medial side indicates disease of the Yin Qiao vessel; inability to step backward while being able to step forward indicates injury to the Taiyang meridian; limping alternating between left and right indicates Wind-Cold-Dampness disease; muscle cramping indicates Cold pathogen in the tendons; joint pulling indicates Cold pathogen in the joints; foot laxity unable to bear weight on the ground indicates emptiness of the great meridians; foot trembling unable to support the body indicates depletion of bone marrow; inability to control the foot indicates Spleen Qi deficiency; inability to lift the foot indicates Spleen Qi excess; throwing hands and kicking feet indicates irritability; climbing walls and roofs indicates manic anger due to excess; tendon laxity preventing walking indicates Liver labor; discarding clothes and running wildly indicates Stomach excess; inability to sit while standing, or stand while sitting, indicates intermingling of Yin and Yang, meaning both are diseased. These are all based on posture. Observing form and posture together, examining meridians to distinguish conditions, verifying the cold or warmth of the feet, palpating the movement or stillness of the pulse, consulting the Four Diagnostic Methods, and investigating the Three Causes, one can understand the general outline of changes in diseases and differences between root and branch manifestations.