What do the fifteen collateral vessels represent? What are their functions?

The twelve meridians and the Ren and Du meridians each have a collateral, which, together with the spleen's large collateral, make a total of 15 collaterals, known as the fifteen collaterals, named after the acupoints from which they originate. Let’s find out together below!

⑴ The collateral meridian of Hand Taiyin: It branches out from Lieque point, starts above the wrist joint, and goes to the Hand Yangming Meridian half an inch behind the wrist; its branch meridian runs parallel to the Hand Taiyin Meridian, goes straight into the palm, and spreads to the thenar eminence.

⑵ The collateral of the Hand Yangming Meridian: It branches out from the Pianli point and goes to the Hand Taiyin Meridian three inches behind the wrist; its branch goes up along the arm, passes through the shoulder joint, ascends to the mandibular angle, and spreads over the teeth. Its branch enters the ear and meets the main meridian.

⑶ The collateral of the Foot Yangming Meridian: It branches out from the Fenglong point, eight inches above the outer ankle, and goes to the Foot Taiyin Meridian; its branch runs along the outer edge of the tibia, connects with the head and neck upwards, combines with the pulse qi of each meridian, and connects with the throat downwards.

⑷ The collateral of the Taiyin meridian of the foot: It branches out from the Gongsun point, one inch behind the metatarsal joint of the first toe, and goes to the Yangming meridian of the foot; its branch enters the abdominal cavity and connects the intestines and stomach.

⑸ The collateral meridian of Shaoyin Meridian of Hand: It branches out from Tongli acupoint and goes to the Taiyang Meridian of Hand one inch behind the wrist; its branch branches off and goes up one and a half inches behind the wrist, enters the heart along the main meridian, goes up to the base of the tongue, and connects to the eye system.

⑹ The collateral meridian of the Hand Taiyang Meridian: It branches out from the Zhizheng point and injects into the Hand Shaoyin Meridian five inches behind the wrist; its branch meridian ascends through the elbow and connects to the shoulder joint.

⑺ The branch channel of the foot-taiyang meridian: It branches out from the Feiyang point, seven inches above the outer ankle, and goes to the foot-shaoyin meridian.

⑻ The collateral of the Foot Shaoyin Meridian: It branches out from the Dazhong point, goes around the heel behind the inner ankle, and goes to the Foot Taiyang Meridian; its branch goes up together with the main meridian, goes to the bottom of the pericardium, and goes outward to pass through the waist and spine.

⑼ The branch channel of Hand Jueyin: It branches out from Neiguan point, emerges shallowly between two tendons two inches behind the wrist, goes up along this channel, connects with the pericardium, and connects with the heart system.

⑽ The collateral of the Shaoyang Meridian of the Hand: It branches out from the Waiguan point, two inches behind the wrist, goes around the outside of the arm, enters the chest, and joins the Jueyin meridian of the Hand.

⑾ The branch channel of the foot Shaoyang meridian: It branches out from the Guangming point, five inches above the inner ankle, goes to the foot Jueyin meridian, and connects downward to the dorsum of the foot.

⑿ The branch meridian of the foot Jueyin: It branches out from the Li Gou point, five inches above the inner ankle, and goes to the foot Shaoyang meridian; its branch passes through the tibia, ascends to the testicle, and gathers at the penis.

⒀The collateral of the Ren meridian: It branches out from the Jiuwei (Weiyi) point, descends from the sternum, and spreads in the abdomen.

⒁ The collateral of the Du meridian: It branches out from the Changqiang point, goes up along both sides of the spine to the neck, and spreads on the head; the descending collateral starts from the scapula, goes along the left and right sides of the Foot-Taiyang Meridian, and enters the muscles on both sides of the spine.

⒂ The large meridian of the spleen: It branches out from the Dabao point, emerges shallowly three inches below the Yuanxie point, and spreads to the chest and flanks.