四十六难曰∶老人卧而不寐，少壮寐而不寤者，何也？
然∶经言少壮者，血气盛，肌肉滑，
气道通，荣卫之行，不失于常，故昼日精，夜不寤。老人血气衰、肌肉不滑，荣卫之道涩，故昼日
不能精，夜不寐也。故知老人不得寐也。
卫外之血气，日行于阳络二十五度，夜行于阴络二十五度，分为昼夜。故气至阳则卧起而目
张，气至阴则休止而目瞑。夫血气者，充肤热肉，淡渗皮毛之血气。肌肉者，在外皮肤之肌肉，
在内募原之肌肉。气道者，肌肉之纹理，三焦通会元真之处，血气之所游行出入者也。老人血气衰，
肌肉干枯，血气之道涩滞，故昼不精明，夜多不寐也。少壮者，血气盛，肌肉滑利，血气之道流
通，而不失其出入之常度，故昼精明，夜多寐也。是老人之寤而不寐，少壮之寐而不寤，系乎荣卫
血气之有余不足也。
四十七难曰∶人面独能耐寒者何也？
然∶人头者，诸阳之会也。诸阴脉皆至颈胸中而还，独诸
阳脉皆上至头耳，故令面耐寒也。
人面独能耐寒者，以六阳经之脉，皆上至头，六阴经之脉，皆不上头故也。《灵枢·邪气脏腑
病形篇》曰∶首面与身形也，属骨连筋，同血合于气耳。天寒则裂地凌冰，其卒寒或手足懈惰，
而其面不衣，何也？岐伯曰∶十二经脉，三百六十五络，其血气皆上于面而走空窍，其精阳气上
走于目而为睛，其别气走于耳而为听，其宗气上出于鼻而为臭，其浊气出于胃，走唇舌而为味，
其气之津液，皆上薰于面，其皮浓，其肉坚，故天热甚寒，不能胜之也，此即其义。而又引逆
顺肥瘐篇，手三阴从脏走手，手三阳从手走头，足三阳从头走足，足三阴从足走胸之义以证之。
言头面为诸阳之会，是以三阳之脉，上循于头。然厥阴之脉，上额交巅，下循颊里，而经不云
者，乃略言之耳。盖阴阳寒热之气，皆从下而上升，故岐伯谓十二经脉，三百六十五络，其血
气皆上于面，而走空窍也。
上第三卷，三十难至四十七难，论脏腑。
第四十六难问道：老年人躺下后无法入睡，年轻人睡着后不会轻易醒来，这是什么原因呢？
回答说：医经中说，年轻人血气旺盛，肌肉滑润，气道通畅，营气和卫气的运行不失常度，所以白天精神饱满，夜晚睡眠安稳。老年人血气衰弱，肌肉干枯不滑，营卫运行的通道涩滞，所以白天精神不能充沛，夜晚也无法入睡。因此知道老年人难以入睡。
卫气和行于体表的血气，白天在阳络运行二十五周，夜晚在阴络运行二十五周，以此划分昼夜。所以当气行于阳分时，人就会起床睁眼；当气行于阴分时，人就会停止活动闭目睡眠。所谓血气，是充盈皮肤、温煦肌肉、淡渗透达皮毛的血气。所谓肌肉，是在外的皮肤下的肌肉，在内的募原处的肌肉。所谓气道，是肌肉的纹理，是三焦通会元气真气的地方，也是血气游行出入的场所。老年人血气衰弱，肌肉干枯，血气运行的道路涩滞，所以白天精神不精明，夜晚大多无法入睡。年轻人血气旺盛，肌肉滑利，血气运行的道路通畅，且不失去出入的正常规律，所以白天精神精明，夜晚大多能安睡。因此，老年人的醒着却睡不着，年轻人的睡着却不惊醒，都取决于营卫血气的有余或不足。
第四十七难问道：为什么人的面部唯独能够耐寒呢？
回答说：头部是诸阳经汇聚的地方。所有的阴脉都只到达颈胸部就返回，只有诸阳脉都上行至头耳部，所以使面部能够耐寒。
人面唯独能耐寒的原因，是因为六条阳经的脉气都上行至头部，而六条阴经的脉气都不上行至头部。《灵枢·邪气脏腑病形篇》说：头和面与身形相连，属于骨骼连接筋脉，共同受气血濡养。天气严寒时，大地开裂，冰凌凝结，突然受寒有时会导致手足懈怠无力，但面部却不需衣物保暖，为什么呢？岐伯说：十二经脉和三百六十五络，它们的气血都上行于面部并通达各个孔窍，其中精纯的阳气上行至眼睛成为视觉，别行的气上行至耳朵成为听觉，宗气上行出于鼻子成为嗅觉，浊气出于胃，上行至唇舌成为味觉，这些气中的津液，都向上熏蒸于面部，加上面部皮肤厚实，肌肉坚实，所以即使天气极热或极寒，也不能伤害它，这就是其中的道理。此处又引用《逆顺肥瘦篇》中“手三阴经从脏走向手，手三阳经从手走向头，足三阳经从头走向足，足三阴经从足走向胸”的理论来证明。说明头面是诸阳经汇聚之处，所以三条阳经的脉气，都上行循行于头部。然而厥阴经的脉气，虽然上额交于巅顶，下行于脸颊内部，但经文没有特别提及，这是略去了它的说法罢了。大概阴阳寒热之气，都是从下方向上升腾，所以岐伯说十二经脉和三百六十五络，它们的气血都上行于面部，并通达各个孔窍。
以上为第三卷，从第三十难到第四十七难，论述的是脏腑相关内容。
Chapter 46 asks: Why do the elderly lie down but fail to sleep, while the young and vigorous sleep without waking?
The response states: The classic texts explain that in the young and vigorous, blood and qi are abundant, muscles are smooth, the qi pathways are unobstructed, and the circulation of Ying (Nutrient) Qi and Wei (Defensive) Qi remains within normal limits. Therefore, they possess mental clarity during the day and sleep soundly at night. In the elderly, blood and qi decline, muscles become dry and lack smoothness, and the pathways for Ying and Wei Qi become sluggish. Consequently, they lack mental vitality during the day and suffer from insomnia at night. Thus, it is understood that the elderly have difficulty sleeping.
The Wei Qi and blood circulating on the exterior travel through the Yang collaterals twenty-five times during the day and through the Yin collaterals twenty-five times at night, thereby dividing the cycle into day and night. When Qi reaches the Yang aspect, one rises and opens the eyes; when Qi reaches the Yin aspect, activity ceases and the eyes close. By "blood and qi," we refer to that which fills the skin, warms the flesh, and permeates the hair follicles and skin surface. By "muscles," we refer to those located externally beneath the skin and internally at the Mouyuan (epigastric region/mesenteric fat). By "qi pathways," we refer to the texture of the muscles, the places where the Sanjiao (Triple Burner) connects with Yuan Zhen (Original True Qi), and the channels through which blood and qi circulate and enter or exit. Because the elderly experience a decline in blood and qi, their muscles become dry, and the pathways for blood and qi become obstructed and sluggish, leading to a lack of mental acuity during the day and frequent insomnia at night. Conversely, the young and vigorous have abundant blood and qi, smooth muscles, and unobstructed pathways for blood and qi that maintain their normal rhythm of entry and exit. Thus, they enjoy mental clarity during the day and restful sleep at night. Therefore, the phenomenon of the elderly being awake yet unable to sleep, and the young sleeping without waking, depends on whether Ying, Wei, blood, and qi are sufficient or deficient.
Chapter 47 asks: Why is it that only the human face can resist cold?
The response states: The head is the convergence point of all Yang meridians. All Yin meridians ascend only to the neck and chest before returning, whereas all Yang meridians ascend to the head and ears. This is why the face can withstand cold.
The reason the face alone resists cold is that the six Yang meridians all ascend to the head, while the six Yin meridians do not ascend to the head. The *Ling Shu* (Spiritual Pivot), Chapter "Pathogenic Factors, Zang-Fu Organs, and Disease Manifestations," states: "The head and face are connected to the body form, linked by bones and sinews, and integrated with blood and qi." When heaven is cold, the earth cracks and ice forms; sudden exposure to cold may cause the hands and feet to become lax and weak, yet the face requires no clothing for warmth. Why is this? Qibo replied: "The twelve primary meridians and the three hundred and sixty-five collaterals, all their blood and qi ascend to the face and flow into the orifices. Their refined Yang Qi ascends to the eyes to provide vision; their branch Qi flows to the ears to provide hearing; their Zong Qi (Pectoral Qi) emerges from the nose to provide smell; their turbid Qi originates from the Stomach and flows to the lips and tongue to provide taste. The fluids and essence of these Qi all steam upward to nourish the face. Furthermore, the skin is thick and the muscles are firm; therefore, neither extreme heat nor extreme cold can overcome them." This explains the principle. Additionally, the chapter cites the theory from "Ni Shun Fei Yu" (Reversed and Smooth, Fat and Thin): "The three Yin meridians of the hand travel from the Zang organs to the hands; the three Yang meridians of the hand travel from the hands to the head; the three Yang meridians of the foot travel from the head to the feet; the three Yin meridians of the foot travel from the feet to the chest." This serves as proof. It states that the head and face are the convergence of all Yang meridians, hence the three Yang meridians ascend along the head. However, although the Jueyin meridian ascends to the forehead and crosses the vertex, then descends along the cheeks, the text omits specific mention of it, likely due to brevity. Generally, the Qi of Yin-Yang and Cold-Heat ascends from below. Thus, Qibo stated that the blood and qi of the twelve primary meridians and three hundred and sixty-five collaterals all ascend to the face and flow into the orifices.
The above constitutes Volume III, covering Chapters 30 to 47, discussing Zang-Fu organs.