经云∶大肠者，传道之官，变化出焉。又云∶回肠当脐左回十六曲，大四寸，径一寸
寸之少半，长二丈一尺，受谷一斗，水七升半。又云∶广肠附脊以受回肠，乃出滓秽之
路。大八寸，径二寸，寸之大半，长二尺八寸，受谷九升三合八分合之一。是经多气少血。
《难经》曰∶大肠重二斤十二两，肛门重
十二两。
张介宾曰∶按回肠者，以其回叠也；广肠者，即回肠之更大者；直肠者，又广肠之
末节，下连肛门也。
\r手阳明大肠腑图\p06-d43a50.bmp\r
大肠手阳明之脉，起于大指次指之端，循指上廉，出合谷两骨之间，上入两筋之中，循
臂上廉，入肘外廉，上 外前廉，上肩出 骨之前廉，上出于柱骨之上会，下入缺盆，络
肺下膈属大肠。其支者，从缺盆上颈贯颊，入下齿中，还出挟口，交人中──左之右，右
之左──上挟鼻孔。
\r大肠经循行图\p06-d43a51.bmp\r
阳明之脉手大肠，次指内侧起商阳，循指上廉出合谷，岐骨两筋循臂肪，入肘外廉
循外，肩端前廉柱骨旁，从肩下入缺盆内，络肺下膈属大肠。支从缺盆直上颈，斜贯颊
前下齿当，环出人中交左右，上侠鼻孔注迎香。
【注】手阳明大肠经之脉，起于大指次指内廉之端。出于大指者，谓出于大指少商穴
也，本经之络。其支者，直出于次指之端，以交于手阳明大肠经之商阳穴，故曰∶起于大
指次指之端也。从商阳穴循食指上廉，二间、三间穴也。从三间穴循出两骨之间，合谷穴
也。从合谷上两筋之间，阳溪穴也。从阳溪穴循臂上廉至偏历、温溜、下廉、上廉、三
里穴也。从三里穴入肘外廉，曲池穴也。从曲池穴上 外前廉，肘 、五里、臂 穴也。
从臂 穴上肩，肩 穴也。从肩 穴出 骨之前廉，巨骨穴也。从巨骨穴上出于柱骨之会
上，言会于督脉之大椎穴也；自督脉大椎穴入交足阳明胃经之缺盆穴。络肺下膈属大肠
者，谓其支从缺盆上颈，复循本经之天鼎穴，贯颊至扶突穴也。从扶突穴入下齿中禾 穴，
从禾 穴还出挟口交人中──左之右，右之左──上挟鼻孔迎香穴而终，以交于足阳明胃经也。
医经记载说：大肠是传导糟粕的官职，食物的消化变化由此产生。又说：回肠位于肚脐左侧，回旋十六圈，宽度四寸，直径一寸又三分之一寸，长度二丈一尺，能容纳谷物一斗，水七升半。又说：广肠依附于脊柱以接收回肠，这是排出残渣秽物的通道。广肠宽八寸，直径二寸又三分之二寸，长度二尺八寸，能容纳谷物九升三合八分合一。这条经脉多气少血。《难经》说：大肠重二斤十二两，肛门重十二两。
张介宾说：按回肠的名称，是因为它回旋重叠；广肠，就是比回肠更大的部分；直肠，又是广肠的最末一节，向下连接肛门。
手阳明大肠经的脉气，起始于食指末端，沿着食指上缘，出于合谷穴在两骨之间，向上进入两筋之中，沿着手臂上缘，进入肘部外侧，沿上臂外侧前缘，上行至肩部，出于肩峰前缘，向上出于柱骨（颈椎）的上会合处，向下进入缺盆，联络肺脏，向下穿过膈肌，属于大肠。它的支脉，从缺盆上行至颈部，贯穿面颊，进入下齿中，回转出来夹住口角，在人中穴交叉——左边交右边，右边交左边——向上夹鼻孔两侧。
阳明经的手大肠经，起于食指内侧端的商阳穴，沿着食指上缘出于合谷穴，在歧骨和两筋间沿手臂外侧，进入肘部外侧，沿上臂外侧，经过肩端前缘、柱骨旁，从肩部向下进入缺盆内，联络肺脏，向下穿过膈肌，属于大肠。支脉从缺盆直上颈部，斜贯面颊前方至下齿，环绕出人中穴左右交叉，向上夹鼻孔注入迎香穴。
【注释】手阳明大肠经的脉气，起始于食指内侧端的末端。所谓“出于大指”，是指出于大拇指的少商穴，这是本经的络脉分支。其支脉，直接出于食指的末端，以交于手阳明大肠经的商阳穴，所以说：“起始于食指和拇指的末端”。从商阳穴沿着食指上缘，经过二间、三间穴。从三间穴沿着两骨之间而出，是合谷穴。从合谷穴向上到两筋之间，是阳溪穴。从阳溪穴沿着手臂上缘至偏历、温溜、下廉、上廉、三里穴。从三里穴进入肘部外侧，是曲池穴。从曲池穴向上至上臂外侧前缘，经过肘髎、五里、臂臑穴。从臂臑穴上行至肩部，是肩髃穴。从肩髃穴出于肩峰骨的前缘，是巨骨穴。从巨骨穴向上出于柱骨的会合处以上，意思是会合于督脉的大椎穴；从督脉大椎穴进入并交于足阳明胃经的缺盆穴。联络肺脏，向下穿过膈肌，属于大肠，是指其支脉从缺盆上行至颈部，再沿本经的天鼎穴，贯穿面颊至扶突穴。从扶突穴进入下齿中的禾髎穴，从禾髎穴回转出来夹住口角交于人中穴——左边交右边，右边交左边——向上夹鼻孔至迎香穴而终结，以此交于足阳明胃经。
The classic texts state: The Large Intestine is the official responsible for transmission, where changes and transformations occur. It is further stated that the Hui Chang (Revolving Intestine) is located to the left of the umbilicus, revolving sixteen times, with a width of four cun, a diameter of one cun and one-third cun, and a length of two zhang and one chi, capable of holding one dou of grain and seven sheng and half a sheng of water. It is also stated that the Guang Chang (Broad Intestine) attaches to the spine to receive the Revolving Intestine; this is the pathway for expelling waste and filth. The Broad Intestine is eight cun wide, two cun and two-thirds cun in diameter, and two chi and eight cun long, capable of holding nine sheng, three he, and one-eighth he of grain. This meridian is characterized by abundant Qi and scarce Blood. The Nan Jing states: The Large Intestine weighs two jin and twelve liang, and the An Men (Anus) weighs twelve liang.
Zhang Jiebin stated: Regarding the Hui Chang, its name derives from its revolved and folded structure; the Guang Chang is the larger portion of the Hui Chang; the Zhi Chang (Straight Intestine) is the terminal segment of the Guang Chang, connecting downwards to the Anus.
The Hand-Yangming Large Intestine Fu Meridian originates at the tip of the radial side of the index finger, follows the upper medial border of the finger, emerges between the two bones at Hegu (LI4), ascends into the space between the two tendons, follows the upper lateral border of the forearm, enters the lateral aspect of the elbow, ascends along the anterior lateral border of the upper arm, reaches the shoulder emerging before the anterior border of the acromion, ascends above the meeting point of the vertebral column, descends into the Supraclavicular Fossa (Quepen), connects with the Lung, passes downward through the diaphragm, and belongs to the Large Intestine. Its branch arises from the Supraclavicular Fossa, ascends to the neck, penetrates the cheek, enters the lower teeth, returns to emerge flanking the mouth, crosses at Renzhong (GV26)—left crossing right, right crossing left—and ascends to flank both sides of the nostrils.
The Yangming Hand-Large Intestine meridian starts at Shangyang (LI1) on the inner side of the index finger, follows the upper border of the finger out to Hegu (LI4), traverses the gap between the bones and tendons along the forearm, enters the lateral elbow, follows the lateral upper arm, passes the anterior border of the shoulder and beside the vertebral column, descends from the shoulder into the Supraclavicular Fossa, connects with the Lung, passes downward through the diaphragm, and belongs to the Large Intestine. The branch rises straight from the Supraclavicular Fossa to the neck, obliquely penetrates the anterior cheek to the lower teeth, circles out to cross Renzhong (GV26) left and right, and ascends to flank the nostrils, entering Yingxiang (LI20).
[Annotation] The meridians of the Hand-Yangming Large Intestine originate at the end of the medial border of the index finger. The phrase "emerges from the thumb" refers to Shaoshang (LU11) of the thumb, which is the collateral branch of this meridian. Its branch directly emerges from the tip of the index finger to connect with Shangyang (LI1) of the Hand-Yangming Large Intestine Meridian; hence it is said to "originate at the ends of the index and thumb fingers." From Shangyang (LI1), following the upper border of the index finger, are Erjian (LI2) and Sanjian (LI3). From Sanjian (LI3), emerging between the two bones, is Hegu (LI4). From Hegu (LI4) ascending between the two tendons is Yangxi (LI5). From Yangxi (LI5), following the upper lateral border of the forearm to Pianli (LI6), Wenliu (LI7), Xia Lian (LI8), Shang Lian (LI9), and Sanli (ST36/LI10 context implies ST36 but text says Sanli which usually refers to Zusanli ST36, however in LI channel context often refers to specific points or is a textual variation, here strictly translating as Sanli), are the points. From Sanli entering the lateral aspect of the elbow is Quchi (LI11). From Quchi (LI11) ascending to the anterior lateral border of the upper arm are Zhou Liao (LI12), Wuli (LI13), and Bi Nao (LI14). From Bi Nao ascending to the shoulder is Jianyu (LI15). From Jianyu (LI15) emerging before the anterior border of the acromial bone is Gugu (LI16). From Gugu (LI16) ascending above the meeting of the vertebral column, it meets Dazhui (GV14) of the Du Mai; from Dazhui (GV14) of the Du Mai, it enters and intersects with Quepen (ST12) of the Foot-Yangming Stomach Meridian. Connecting with the Lung, passing downward through the diaphragm, and belonging to the Large Intestine refers to the branch arising from Quepen, ascending to the neck, again following Tianding (LI17) of this meridian, penetrating the cheek to Futu (LI18). From Futu (LI18) entering the lower teeth is Heliao (LI19); from Heliao (LI19) returning to emerge flanking the mouth and crossing at Renzhong (GV26)—left crossing right, right crossing left—ascending to flank the nostrils to Yingxiang (LI20) to conclude, thereby connecting with the Foot-Yangming Stomach Meridian.