《素问·宣明五气论》曰∶五劳所伤∶久视伤血，久卧伤气，久坐伤肉，久立伤骨，久行伤筋，是谓五
劳所伤。
肝藏血而开窍于目，故久视劳目则伤血；肺为华盖，权衡一身之气，敷布周流，循环不息，久卧则肺气不
舒而伤矣；脾司转运而主肌肉，久坐则脾不运而肌肉伤矣；久立则劳骨，久行则劳筋，故皆伤。始而伤血、
气、肉、骨、筋，久则伤及五脏，是谓五劳所伤者也。然身逸者，气血多滞，而但劳心，则直伤五内，其病
尤重也。
《灵枢·忧恚无言篇》帝曰∶人之卒然忧恚而言无音者，何道之塞也？少师曰∶咽喉者，水谷之道也；
喉咙者，气之所以上下者也；会厌者，音声之户也，口唇者，音声之扇也；舌者，音声之机也；悬雍垂者，音
声之关也；颃颡者，分气之所泄也；横骨者，神气所使，主发舌者也。故人之鼻洞涕出不收者，颃颡不开，
分气失也。是故厌小而疾薄，则发气疾，其开阖利，其出气易；其厌大而浓，则开阖难，其气出迟，故重言
也。人卒然无音者，寒气客于厌，则厌不能发，发不能下，至其开阖不致，故无音。
肺之气喉在前近胸，胃之咽喉在后近背，喉口中间有薄膜一片，名会厌，厌者，掩盖喉口者也，饮食入口，
则掩盖气喉而咽喉开，言语发声，则掩盖咽喉而气喉开，故如饮食到喉，或值言语而气喉开，则食饮误下气喉，
与肺气格逆，则必咳呛而出，以气喉在前故也。是故会厌为音声之户；口唇为音声之扇；舌动方能变声音而成
语，故舌为机，如舌强或痿，虽有声不能成语矣；上 喉口垂下之软肉名悬雍，故为音声之关也；横骨者，舌
根之嫩骨，本由心脏所生，故为神气所使，主发动其舌，以舌为心之苗也；颃颡者，顶前额内之处，津气循喉
上升至颃颡，如烟雾之四布周行也，故颃颡之气不开，不能分布津气，则由鼻下溜成涕，其气不能约束，故名
鼻洞。此因清阳不足，不能透开颃颡，故婴孩老年，多有此病。凡语言便利及迟钝难出，皆会厌有大小浓薄不
同之故。如其应对之敏拙，由心之灵昧，非关于外也。若寒气客于会厌，不能开阖，则卒然无音；其卒然忧恚，
气必逆乱，以伤会厌而机关不利，可以类推而知也。
帝曰∶刺之奈何？岐伯曰∶足之少阴，上系于舌，络于横骨，终于会厌。两泻其血脉，浊气乃辟。会厌之
脉，上络任脉，取之天突，其厌乃发也。
足少阴肾经之脉，上行系舌本，络横骨，而终于会厌；会厌之脉，又上络任脉。故用针泻少阴、任脉两处
之血脉，则浊气辟除而清阳透达，其会厌声音乃发也。天突，任脉络穴，在结喉下。
《素问·宣明五气论》说：五种过度劳作会损伤人体：长时间注视损伤血液，长时间躺卧损伤气，长时间坐着损伤肌肉，长时间站立损伤骨骼，长时间行走损伤筋脉，这被称为五种劳作所导致的损伤。
肝脏贮藏血液并开窍于眼睛，所以长时间注视使眼睛疲劳就会损伤血液；肺位于五脏最高处（华盖），总司全身之气，布散周身，循环不息，长时间躺卧则肺气不舒展而受到损伤；脾主管运化并主司肌肉，长时间坐着则脾的运化功能受阻从而损伤肌肉；长时间站立使骨骼劳累，长时间行走使筋脉劳累，所以都会造成损伤。起初是血液、气、肌肉、骨骼、筋脉受损，时间久了则会波及五脏，这就是所谓的五种劳作所导致的损伤。然而身体安逸的人，气血容易停滞，如果只用心劳神，则会直接损伤内脏，其病情尤为严重。
《灵枢·忧恚无言篇》黄帝问道：人突然因忧愁愤怒而不能说话的原因是什么？是哪条通道堵塞了？少师回答说：咽喉是水谷通行的道路；喉咙是气体上下出入的部位；会厌是声音发出的门户；口唇是声音传播的扇子；舌是声音变化的枢纽；悬雍垂是声音的关键；颃颡（鼻咽部）是分流气息的地方；横骨受神气支配，主要控制舌的运动。所以人的鼻孔流涕不止无法收敛，是因为颃颡不能开启，导致分流气息的功能失常。因此，会厌小而薄，则发声迅速，开阖灵活，出气容易；会厌大而厚，则开阖困难，出气迟缓，所以说话声音重浊。人突然失音，是因为寒气客居在会厌，导致会厌不能正常启闭，开阖失调，所以发不出声音。
肺的气道（喉）在前面靠近胸部，胃的食道（咽喉）在后面靠近背部，喉口中间有一片薄膜，名叫会厌，“厌”有掩盖的意思，用来掩盖喉口。饮食入口时，会厌掩盖气道而食道打开；言语发声时，会厌掩盖食道而气道打开。所以如果食物到了喉部，或者正在说话时气道打开，食物误入气道，与肺气相格拒逆冲，就一定会咳嗽呛出，这是因为气道在前面的缘故。因此，会厌是声音的门户；口唇是声音的扇子；舌头运动才能改变声音形成语言，所以舌是枢纽，如果舌体僵硬或痿软，即使有声带也无法形成语言；上喉口下垂的软肉名叫悬雍垂，所以它是声音的关键；横骨是舌根处的嫩骨，原本由心脏生成，所以受神气支配，主要发动舌头，因为舌是心的苗窍；颃颡是头顶前额内的部位，津液和气息顺着喉咙上升至颃颡，像烟雾一样四处散布运行。所以如果颃颡之气不能开启，就不能分布津液和气息，就会从鼻子下面流下成为鼻涕，气息不能约束，所以叫鼻洞。这是因为清阳之气不足，不能透达开启颃颡，所以婴儿和老年人多有此病。凡是语言流利或迟钝难出，都是因为会厌的大小厚薄不同造成的。至于应对反应的敏捷或笨拙，是由心的灵明或昏昧决定的，与外部器官无关。如果寒气客居在会厌，导致不能开阖，就会突然失音；如果是突然因忧愁愤怒，气机必然逆乱，从而伤害会厌导致机关不利，这种情况可以据此类推而知晓。
黄帝问道：如何针刺治疗？岐伯回答说：足少阴肾经向上联系到舌根，联络横骨，终止于会厌。在两处泻其血脉，浊气就能排除。会厌的脉络，向上联络任脉，取穴天突，这样会厌就能正常启闭发声了。
足少阴肾经的经脉，上行系连舌本，联络横骨，而终止于会厌；会厌的脉络，又向上联络任脉。所以用针法泻足少阴经和任脉两处的血脉，则浊气被清除而清阳之气透达，会厌的声音功能就能恢复。天突穴是任脉的络穴，位于结喉下方。
The *Suwen: Treatise on the Manifestation of the Five Qi* states: The five types of overexertion cause injury: prolonged gazing injures blood, prolonged lying down injures qi, prolonged sitting injures flesh, prolonged standing injures bones, and prolonged walking injures sinews. This is referred to as the injuries caused by the five types of overexertion.
The Liver stores blood and opens into the eyes; therefore, prolonged gazing fatigues the eyes and injures the blood. The Lung acts as the canopy (Huagai), governing the qi of the entire body, distributing it throughout, and circulating endlessly. Prolonged lying down causes Lung qi to become stagnant and thus injured. The Spleen governs transportation and transformation and controls the muscles; prolonged sitting impairs Spleen function and injures the muscles. Prolonged standing fatigues the bones, and prolonged walking fatigues the sinews, so both result in injury. Initially, the blood, qi, flesh, bones, and sinews are injured; over time, this extends to the Zang organs. This is what is meant by the injuries caused by the five types of overexertion. However, individuals who are physically idle often have stagnant blood and qi. If they only engage in mental exertion, it directly injures the internal organs (Wu Nei), and the resulting disease is particularly severe.
In the *Lingshu: Chapter on Speechlessness Due to Grief and Anger*, the Yellow Emperor asked: What causes sudden loss of voice due to grief and anger? Which pathway is blocked? Shaoshi replied: The pharynx (Yanhou) is the pathway for water and food; the larynx (Houlong) is where qi ascends and descends; the epiglottis (Huiyan) is the gate of sound; the lips are the fan of sound; the tongue is the mechanism of sound; the uvula (Xuan Yong Chui) is the lock of sound; the nasopharynx (Hangsang) is where qi is distributed; and the transverse bone (Heng Gu) is controlled by spirit and qi, primarily governing tongue movement. Therefore, if nasal discharge flows uncontrollably, it is because the nasopharynx fails to open, leading to a failure in distributing qi. Thus, if the epiglottis is small and thin, sound emission is rapid, opening and closing are smooth, and air exits easily; if the epiglottis is large and thick, opening and closing are difficult, air exit is slow, and speech becomes hoarse. Sudden aphonia occurs when cold pathogen lodges in the epiglottis, preventing it from moving up or down, causing dysfunction in opening and closing, resulting in no sound.
The pulmonary airway (Hou) is located anteriorly near the chest, while the esophageal throat (Yanhou) is posteriorly near the back. Between them lies a membrane called the epiglottis (Huiyan); "Yan" means to cover, serving to cover the glottis. When food enters the mouth, the epiglottis covers the airway and opens the esophagus; when speaking, it covers the esophagus and opens the airway. Therefore, if food reaches the throat or if the airway opens during speech, food may accidentally enter the airway, clashing with Lung qi and causing coughing and choking, because the airway is anterior. Thus, the epiglottis is the gate of sound; the lips are the fan of sound; the tongue moves to modulate sound into language, so the tongue is the mechanism. If the tongue is stiff or flaccid, speech cannot be formed despite vocal cord function. The soft tissue hanging from the upper laryngeal opening is called the uvula (Xuan Yong), serving as the lock of sound. The transverse bone (Heng Gu) is the tender bone at the root of the tongue, originally generated by the Heart, so it is governed by spirit and qi to move the tongue, as the tongue is the sprout of the Heart. The nasopharynx (Hangsang) is the area inside the forehead above the roof of the mouth; fluids and qi ascend through the throat to the nasopharynx, spreading like smoke. If nasopharyngeal qi fails to open, fluids and qi cannot distribute, flowing down from the nose as mucus; since qi cannot constrain it, it is called rhinorrhea (Bi Dong). This is due to insufficient clear yang failing to penetrate and open the nasopharynx, which is why infants and the elderly often suffer from this condition. Variations in speech fluency or difficulty arise from differences in the size and thickness of the epiglottis. Responsiveness in conversation depends on the clarity or dullness of the Heart, not external factors. If cold pathogen lodges in the epiglottis, preventing opening and closing, sudden aphonia occurs; if sudden grief and anger cause qi rebellion, injuring the epiglottis and impairing its mechanism, this can be inferred analogously.
The Yellow Emperor asked: How should acupuncture be applied? Qibo replied: The Foot-Shaoyin Kidney Meridian ascends to connect with the tongue root, links with the transverse bone, and terminates at the epigllottis. By draining the blood vessels in these two areas, turbid qi will be expelled. The meridian of the epiglottis connects upward to the Ren Mai (Conception Vessel). Select Tian Tu (CV22) to restore epiglottic function.
The Foot-Shaoyin Kidney Meridian ascends to tie the tongue root, links the transverse bone, and terminates at the epiglottis; the epiglottic meridian further connects upward to the Ren Mai (Conception Vessel). Therefore, using needle therapy to drain the blood vessels of the Foot-Shaoyin and Ren Mai clears turbid qi and allows clear yang to penetrate, restoring the voice via the epiglottis. Tian Tu (CV22) is the Luo-Connecting point of the Ren Mai, located below the Adam's apple.