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。
小肠，是受纳和盛装水谷的腑，与心互为表里，手太阳经是其所属的经脉。如果小肠经气断绝，六天后会死亡；经气断绝时，头发会僵硬直立像麻秆一样，汗出不止，身体不能屈伸。另外，心病传变至小肠，若出现小肠咳，则表现为气息急促地一起呼出。（所谓“气咳”，是指气息一齐冲出。）
小肠实证多因热邪所伤，热邪伤则生口疮；虚证多因寒邪所伤，寒邪伤则排泄脓血，或者排泄黑色液体，其病根在于小肠。小肠受寒则导致腹泻，若有肿胀且伴有热邪久留不去，则会逐渐形成痔疮；若有积滞，则傍晚发热而早晨退热；病气发作时，使人腰部以下感觉沉重，进食后感到窘迫困难且排便艰难，这是其征候。小肠胀满则小腹胀满，牵引腰部疼痛甚至发生厥逆；邪气侵入小肠，则梦见在集市井邑中聚集，或者咽喉痛、下巴肿，不能回头，肩部感觉像被拔起或折断一样。又说：心，是君主之官，是神志寄居的地方，其脏体坚固致密，不易受伤，一旦受伤则神气离去，神气离去则心功能衰竭死亡。所以人心通常很少生病，一旦发病即属死症不可治愈，只有小肠容易受病。另外，左寸口脉阳绝者，则没有小肠的脉象，六天后死亡。若有热邪，则小便赤红涩痛，实证则口中生疮，身体发热往来不定，心中烦闷，身体沉重。小肠是与舌相关的器官，功能调和则能言语，关节灵活，善于辨别味道。若小肠虚，则左寸口脉浮而微弱，软弱无力禁不起按压，病症表现为惊惧狂乱、心神无主，心下空虚感且不能言语。以上是小肠虚实寒热以及生死逆顺的脉证诊断法则。
《主治备要》说：小肠经气变动所生的疾病，包括咽喉痛、下巴肿，不能回顾，肩部感觉像被拔起或折断；小肠经作为主液（血）病变的经脉，其病症还包括耳聋、目黄、脸颊肿，颈、下巴、肩、肘、臂外侧后方疼痛。《脉诀》说：左寸部，是小肠和心脉发出的部位，先用轻手诊得，说明小肠属表；后用重手诊得，说明心属里。心合血脉，心脉循行于血脉之中，持脉指法，如六颗豆子的重量，按至血脉处所得为浮脉；稍稍加力，脉道粗大的为大脉；再稍稍加力，脉道润软的为散脉。这是浮大散脉，是心脏未病时的脉象特征。心脉的本部位于血脉之中，若脉象出于血脉之上，显现于皮肤之间，这是浮脉；若入于血脉之下，显现于筋骨之间，这是沉脉。
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.