Twelve channels

Also twelve regular channels. The twelve major pathways of the channel and network vessels system, each associated with a viscus or bowel and passing along a limb. The Líng Shū (Chapter 33) states, The twelve channel vessels internally home to bowels or viscera and externally nets the limbs and joints (夫十二经脉者, 内属于府藏, 外络于肢节 fū shí èr jīng mài zhě, nèi shǔ yú fǔ zàng, wài luò yú zhī jié).

Three Hand Yīn Channels

• Hand greater yīn (tài yīn) lung channel (手太阴肺经 shǒu tài yīn fèi jīng), lung channel, abbreviated to LU in English
• Hand reverting yīn (jué yīn) pericardium channel (手厥阴心包经 shǒu jué yīn xīn bāo jīng), pericardium channel, PC
• Hand lesser yīn (shào yīn) heart channel (手少阴心经 shǒu shào yīn xīn jīng), heart channel, HT

Three Hand Yáng Channels

• Hand yáng brightness (yáng míng) large intestine channel (手阳明大肠经 shǒu yáng míng dà cháng jīng), large intestine channel, LI
• Hand lesser yáng (shào yáng) triple burner channel (手少阳三焦经 shǒu shào yáng sān jiāo jīng), triple burner channel, TB
• Hand greater yáng (tài yáng) small intestine channel (手太阳小肠经 shǒu tài yáng xiǎo cháng jīng), small intestine, SI

Three Foot Yīn Channels

• Foot greater yīn (tài yīn) spleen channel (足太阴脾经 zú tài yīn pí jīng), spleen channel, SP
• Foot reverting yīn (jué yīn) liver channel (足厥阴肝经 zú jué yīn gān jīng), liver channel, LR
• Foot lesser yīn (shào yīn) kidney channel (足少阴肾经 zú shào yīn shèn jīng), kidney channel, KI

Three Foot Yáng Channels

• Foot yáng brightness (yáng míng) stomach channel (足阳明胃经 zú yáng míng wèi jīng), stomach channel, ST
• Foot lesser yáng (shào yáng) gallbladder channel (足少阳胆经 zú shào yáng dǎn jīng), gallbladder channel, GB
• Foot greater yáng (tài yáng) bladder channel (足太阳膀胱经 zú tài yáng páng guāng jīng), bladder channel, BL

Each of the twelve channels is duplicated on either side of the body. Each traverses an inner or outer face of a limb. Inside the body, each channel homes to one of the twelve internal organs, the yīn channels to the viscera and the yáng channels to the bowels. It then nets its exterior-interior paired organ. For example, the hand lesser yīn (shào yīn) channel homes to the heart and nets the small intestine, while the hand greater yáng (tài yáng) channel homes to the small intestine and nets the heart.

Naming of the Channels

Each channel is known by a name composed of three parts: hand or foot; yīn or yáng, and bowel or viscus.

Viscus /bowel: Six of the twelve channels each home to a viscus; the other six each home to a bowel. Only one channel homes to each viscus or bowel, hence the viscus/bowel part of the channel name is unique.

Hand /foot: The six channels that pass over the lower limbs have the word foot as part of their name; the six that pass over the upper limbs have hand in their name. Each inner or outer face of the limbs is traversed by three channels.

Yīn /yáng: According to yīn-yáng theory, the inner faces of the limbs and the ventral aspect of the trunk are yīn, while the outer faces of limbs and the dorsal aspect of the trunk are yáng. The viscera are yīn, while the bowels are yáng.

The six channels that pass over the inner faces of the limbs and the ventral aspect of the trunk and that home to a viscus are labeled as yīn; the six that pass over the outer faces of the limbs and dorsal aspect of the trunk and that home to a bowel are labeled as yáng.

The yīn and yáng channels are each divided into three sub-types. The yīn channels are thus designated as greater yīn (tài yīn), lesser yīn (shào yīn), and reverting yīn (jué yīn). The yáng channels are designated as greater yáng (tài yáng), lesser yáng (shào yáng), and yáng brightness (yáng míng). We refer to these six names as yīn-yáng designations.

Two channels share each yīn-yáng designation, one traversing the upper limbs and the other traversing the lower limbs. For example, two channels share the designation greater yīn (tài yīn): the hand greater yīn (tài yīn) lung channel and foot greater yīn (tài yīn) spleen channel.

The yīn-yáng designations indicate the strength of yīn and yáng qì. Greater yīn (tài yīn) has the most exuberant yīn qì; lesser yīn (shào yīn) has weaker yīn qì; and reverting yīn (jué yīn) has the weakest yīn qì (reverting to yáng).

As to the yáng channels, there is disagreement. According to one view, yáng brightness (yáng míng) has the most exuberant yáng qì, followed by greater yáng (tài yáng), and lesser yáng (shào yáng). According to a second view, yáng brightness (yáng míng) lies between greater yáng (tài yáng) and lesser yáng (shào yáng).

Note also that in the Nèi Jīng, the reverting yīn (jué yīn) designated as the first yīn [channel], the lesser yīn (shào yīn) as the second yīn, and greater yīn (tài yīn) as the third yīn. Lesser yáng (shào yáng), yáng brightness (yáng míng), and greater yáng (tài yáng) are designated as the first, second, and third yáng [channels] respectively. This naming system suggests that (some of) the authors of the Nèi Jīng considered yáng brightness (yáng míng) as lying between greater yáng (tài yáng) and lesser yáng (shào yáng).

Because of the disagreement over the strength of qì in the channels, the threefold distinction in the yīn-yáng designation is of dubious significance. It is, however, significant in cold damage theory, where it labels disease of either of the two channels. For example, yáng brightness (yáng míng) disease generically denotes any disorder that affects the hand large intestine and foot stomach channels. In cold damage disease, it is noteworthy that yáng brightness (yáng míng) disease manifests in the greatest heat (heat is yáng).

Distribution of the Channels

The twelve channels have external and internal pathways.

• The external pathways are the parts of the channel that run close to the surface and are hence accessible to needles. In the diagrams provided for each of the channel pathways below, the external pathways are marked with a solid line.
• The internal pathways are the sections that lie deep within the abdominothoracic cavity.

Limbs: The yīn channels are on the medial aspects of the limbs, while the yáng channels are on the lateral aspects. The distribution on the limbs is roughly as follows:

• Anterior margin: greater yīn (tài yīn) and yáng brightness (yáng míng).
• Midline: reverting yīn (jué yīn) and lesser yáng (shào yáng).
• Posterior margin: lesser yīn (shào yīn) and greater yáng (tài yáng).

This is the general pattern of distribution on both the upper and lower limbs. Nevertheless, the three foot yīn channels differ from a level eight cùn above the ankle downward, where the reverting yīn (jué yīn) is at the front, greater yīn (tài yīn) is in the middle, and lesser yīn (shào yīn) as at the back.

Head: The yáng channels run over the face and forehead. The greater yáng (tài yáng) traverses the face and cheek, the apex, and the back of the head. The lesser yáng (shào yáng) traverses the side of the head.

Trunk.

• The three yáng channels of the hand traverse the shoulder and scapular regions.
• The three hand yīn channels all emerge from the armpit.
• The three yáng channels of the foot follow the pattern of distribution described above, namely that the yáng brightness (yáng míng) is toward the front (chest and abdomen), the greater yáng (tài yáng) is most dorsal (close to the spine), and the lesser yáng (shào yáng) traverses the lateral aspect of the trunk.
• The three yīn channels all traverse the ventral aspect of the trunk.

Directions and Interconnectedness of Channels

The Líng Shū (Chapter 55) describes the direction of the channels succinctly as follows: The three hand yīn run from viscus to hand; the three hand yáng run from hand to head; the three foot yáng run from head to foot; the three foot yīn run from foot to abdomen.

The three yīn channels of the hand each start in the chest and proceed along the arm to the fingers, where they interconnect with the three yáng channels of the hand with which they stand in exterior-interior relationship.

• Hand greater yīn (tài yīn) lung → hand yáng brightness (yáng míng) large intestine
• Hand lesser yin heart → hand greater yáng (tài yáng) small intestine
• Hand reverting yīn (jué yīn) pericardium → hand lesser yáng (shào yáng) triple burner

The three yáng channels of the hand each start from the fingertips and proceed up the arms to the head and face, where they interconnect with the three yáng channels of the foot that have the same yīn-yáng designation.

• Hand yáng brightness (yáng míng) large intestine → foot yáng brightness (yáng míng) stomach
• Hand greater yáng (tài yáng) small intestine → foot greater yáng (tài yáng) bladder
• Hand lesser yáng (shào yáng) triple burner → foot lesser yáng (shào yáng) gallbladder

The three yáng channels of the foot each start from the head and face and proceed down to the toes, where they interconnect with the three yīn channels of the foot with which they stand in exterior-interior relationship.

• Foot yáng brightness (yáng míng) stomach → foot greater yīn (tài yīn) spleen
• Foot greater yáng (tài yáng) bladder → foot lesser yīn (shào yīn) kidney
• Foot lesser yáng (shào yáng) gallbladder → foot reverting yīn (jué yīn) liver

The three yīn channels of the foot each start from the toes and proceed up the legs to the abdomen and chest (before continuing upward to the head), where they interconnect with the three yīn channels of the hand that have the same yīn-yáng designation.

• Foot greater yīn (tài yīn) spleen → hand greater yīn (tài yīn) lung
• Foot lesser yīn (shào yīn) kidney → hand lesser yīn (shào yīn) heart
• Foot reverting yīn (jué yīn) liver → hand reverting yīn (jué yīn) pericardium

The yīn and yáng channels standing in exterior-interior relationship interconnect at the extremities:

• The hand greater yīn lung channel interconnects with the hand yáng brightness (yáng míng) large intestine channel at the tip of the index finger.
• The hand lesser yīn (shào yīn) heart channel interconnects with the hand greater yáng (tài yáng) small intestine channel at the tip of the little finger.
• The hand reverting yīn (jué yīn) pericardium channel interconnects with the hand lesser yáng (shào yáng) triple burner channel at the tip of the middle finger.
• The foot yáng brightness stomach channel interconnects with the foot greater yīn (tài yīn) spleen channel at the tip of the big toe.
• The foot greater yáng (tài yáng) bladder channel interconnects with the foot lesser yīn (shào yīn) kidney channel at the little toe.
• The foot lesser yáng (shào yáng) gallbladder channel interconnects with the foot reverting yīn (jué yīn) liver channel at the tuft of hair close to the toenail of the big toe.

The hand and foot yáng channels of the same yīn-yáng sub-designation interconnect at the head:

• The hand yáng brightness (yáng míng) large intestine channel and foot yáng brightness (yáng míng) stomach channel interconnect at the side of the nose.
• The hand greater yáng (tài yáng) small intestine channel interconnects with the foot greater yáng (tài yáng) bladder channel at the inner canthus (the inner corner of the eye).
• The hand lesser yáng (shào yáng) triple burner channel interconnects with the foot lesser yáng (shào yáng) gallbladder channel at the outer canthus.

The hand and foot yīn channels interconnect in the chest.

• The foot greater yīn (tài yīn) spleen channel interconnects with the hand lesser yīn (shào yīn) heart channel in the center of the chest.
• The foot lesser yīn (shào yīn) kidney channel interconnects with the hand reverting yīn (jué yīn) pericardium channel in the chest.
• The foot reverting yīn (jué yīn) liver channel interconnects with the hand greater yīn (tài yīn) lung channel in the lung.

External-Internal Relationships

Like the bowels and viscera to which they belong, the channels form exterior-interior pairs. Yīn channels are interior, while yáng channels are exterior. Although all twelve regular channels have pathways in the surface of the body and in the body’s interior, they are designated as interior or exterior depending on whether they home to a viscus (interior) or a bowel (exterior).

Channels that stand in exterior-interior relationship with each other interconnect at the extremities. In the interior, they each home to their respective viscus or bowel, as well as netting the viscus or bowel of the channel with which they each stand in exterior-interior relationship. Thus, the hand greater yáng (tài yáng) small intestine channel homes to the small intestine and nets the heart, while the lesser yīn (shào yīn) heart channel homes to the heart and nets the small intestine.

Furthermore, the channel divergences and divergent network vessels provide further connections.

The exterior-interior relationship between the channels is utilized in therapy. Disease of one channel can be treated by needling points on the exterior-interior corresponding channel. For example, disease of the lung or lung channel can be treated by needling points on the large intestine channel.

The Sequence of Channels

Qì and blood enter the channel system in the center burner and then flow from one channel to another, circulating endlessly, as shown in the diagram. ChannelNet-Sequence

Notes on Pathway Descriptions and Channel Points

The descriptions of the pathways are based on the original text of the Nèi Jīng but are expressed in terms of modern anatomy. In the overviews of the channel pathways, the main external pathway of the channels, on which acupoints are located, are underlined. The description of the channel pathways is followed by examples of major commonly used acupoints belonging to channel. The information for each point includes location, type of stimulus commonly applied and the angle of the needle insertion, as well as categories to which the point belongs.