小肠者，受盛之腑也，与心为表里，手太阳是其经也。小肠绝者，六日死，绝则发
直如麻，汗出不已，不能屈伸。又心病传小肠，小肠咳则气咳，（气咳）一齐出也。
小肠实则伤热，（伤）热则口疮生；虚则伤寒，伤寒则泄脓血，或〔泄黑〕水，
〔其〕根在小肠也。小肠寒则下，〔肿〕重〔有〕热久不出，则渐生痔；有积则夕
发热而旦止；病气发则使人腰下重，食则窘迫而便难，是其候也。小肠胀则小〔腹 〕
胀，引〔腰而〕痛厥；邪入小肠，则梦聚井邑中，或咽痛颔肿，不可回首，肩似拔，
似折〔也〕。又曰∶心者，主也，神之舍也，其脏（固）密，而不易伤，伤则
神去，神去则（心死）矣。故人〔心〕多不病，病即死不可治也，〔惟〕小肠受病
〔多〕也。又左寸口阳绝〔者〕，（则）无小肠脉也，六日死。有热邪则小便赤涩，实
则口〔生〕疮，身热往来，心中烦闷，身重。小肠主于舌之官也，和则能言，而机关
利健，善别其味也。虚则〔左〕寸〔口〕脉浮而微，软弱不禁按，病惊惧狂无所守，心
下空空然不能言语者。此小肠虚实寒热，生死逆顺脉证之法也。
《主治备要》云∶是动〔气也〕则病嗌痛颔肿，不可以顾，肩似拔， 似折，〔是〕
主液（血）所生病者，耳聋，目黄，颊肿，颈、颔、肩、 、肘、臂外后廉痛。《脉
诀》云∶左寸，小肠心脉之所出也，先以轻手得之，是〔小肠〕属表；后以重手得之，
是〔心〕属里。心合血脉，心脉循血脉而行，持脉指法，如六菽之重，按至血脉而
得者为浮；稍稍加力，脉道粗大〔者〕为大；又稍稍加力，脉道润软者为散。
此乃浮大而散，心家不病脉之状也。心脉本部，在于血脉，若出于血脉之上，见于皮肤
之间，是其浮也；入于血脉之下，见于筋骨之分，是其沉也。
The Small Intestine is the fu-organ responsible for receiving and storing, and it has an exterior-interior relationship with the Heart. The Hand-Taiyang Bladder Meridian (Note: Text says "Hand Taiyang", which corresponds to Small Intestine meridian in TCM context, though standard WHO term is Small Intestine Meridian of Hand-Taiyang) is its associated channel. If the Qi of the Small Intestine is exhausted, death occurs within six days; upon exhaustion, the hair stands stiffly upright like hemp stalks, sweating continues incessantly, and the body cannot bend or stretch. Furthermore, if Heart disease transmits to the Small Intestine, a cough originating from the Small Intestine manifests as sudden, forceful expulsion of Qi. (This "Qi cough" refers to the simultaneous outburst of breath.)
Excess conditions of the Small Intestine involve injury by Heat, leading to the formation of mouth ulcers; deficiency conditions involve injury by Cold, leading to the discharge of pus and blood, or black fluid, with the root cause lying in the Small Intestine. Cold in the Small Intestine causes diarrhea; if swelling persists with lingering Heat, hemorrhoids gradually develop. Accumulation leads to fever in the evening that subsides by morning. When the pathogenic Qi erupts, it causes heaviness below the waist, urgency and difficulty in defecation after eating, which are its clinical manifestations. Distension of the Small Intestine results in abdominal distension, radiating pain to the lower back and potentially leading to cold extremities (Jue); when pathogenic factors enter the Small Intestine, dreams of gathering in marketplaces occur, or symptoms include sore throat, submandibular swelling, inability to turn the head, and shoulder pain resembling pulling or breaking. It is also said: The Heart is the Sovereign Lord, the residence of the Spirit (Shen). Its zang-organ is solid and dense, difficult to injure; if injured, the Spirit departs, and if the Spirit departs, the Heart dies. Therefore, the Heart rarely suffers from disease; if it does, it is fatal and incurable, whereas the Small Intestine is prone to disease. Additionally, if the Yang aspect of the Left Cun position is exhausted, the pulse of the Small Intestine is absent, and death occurs within six days. Presence of Heat pathogens causes red and scanty urination; excess conditions manifest as mouth ulcers, alternating fever and chills, mental restlessness, and heavy body. The Small Intestine governs the tongue; when harmonious, speech is fluent, joints are agile, and taste discrimination is keen. In deficiency, the Left Cun pulse is floating and faint, weak and tender to pressure; symptoms include fright, fear, mania, lack of mental anchor, emptiness in the epigastrium, and inability to speak. These constitute the methods for diagnosing the excess, deficiency, cold, heat, life-and-death, and favorable-unfavorable patterns of the Small Intestine.
*Zhu Zhi Bei Yao* states: When the Qi of this channel moves abnormally, diseases such as sore throat, submandibular swelling, inability to look back, and shoulder pain resembling pulling or breaking occur. As the channel governing fluids (and Blood), its pathological changes include deafness, yellow eyes, cheek swelling, and pain along the posterior-lateral aspects of the neck, jaw, shoulder, elbow, and arm. *Mai Jue* states: The Left Cun position is where the pulses of the Small Intestine and Heart emerge. Light palpation reveals the Small Intestine's exterior nature; heavy palpation reveals the Heart's interior nature. The Heart combines with the Blood vessels, and the Heart pulse travels within them. For pulse diagnosis, applying weight equivalent to six beans until the vessel is felt indicates a Floating pulse; slightly increasing pressure to feel a coarse vessel indicates a Large pulse; further increasing pressure to feel a moist and soft vessel indicates a Scattered pulse. This floating, large, and scattered quality characterizes the pulse of a healthy Heart. The root of the Heart pulse lies within the blood vessels; if it appears above the vessels, visible between the skin layers, it is Floating; if it sinks below the vessels, visible between the sinews and bones, it is Deep.