The Bladder Primary Channel starts at Jingming BL-1 at the inner canthus of the eye. It is reached by a branch that separates from Quanliao SI-18 of the Small Intestine Primary Channel. This forms the Hand-Foot second great circuit of Taiyang.
It then descends to Tianzhu BL-10 in the occipital area, where the external pathway splits into two branches:
The medial branch first travels to Dazhui DU-14 below the 7th spinal process of the cervical vertebra (C7), where it meets the other Yang Primary Channels. From there, the Channel descends parallelly 1.5 cun lateral to the posterior midline.
At the level of the 2nd lumbar vertebra (L2), one internal sub-branch penetrates deep into the abdomen and connects to the Kidneys and the Bladder.
The main externalmedial branch continues descending through the gluteal area and the thigh to Weizhong BL-40 on the popliteal fossa, where it rejoin the lateral branch.
The lateral branch descends to Fufen BL-41 which is 3 cun lateral to the lower border of the spinous process of the 2nd thoracic vertebra (T2). From there, it continues descending, 3 cun parallel to the posterior midline until reaching Zhibian BL-54 at the level of the fourth sacral foramen. It then runs further down to Huantiao GB-30 at the on the buttock and continues along the posterolateral aspect of the thigh to Weizhong BL-40 to meet the medial branch.
From Weizhong BL-40, the Primary Channel continues descending along the posterolateral aspect of the foreleg.
It then reaches Kunlun BL-60 at the lateral malleolus and latterly runs along the lateral border of the foot to Zhiyin BL-67 at the lateral corner of the little toenail. From there, it connects to a branch of the Kidney Primary Channel at Yongquan KID-1 and forms the Foot Yin-Yang second great circuit.
The branches:
Two branches separates from Baihui Du-20 at the vertex.
One internal branch enters deep into the brain, meets the Governing Vessel and emerges at Naohu DU-17 above the occipital protuberance, where it rejoins the external pathway.
From the lateral malleolus, the main Sinew Channel ascends along the Achilles tendon and binds in the area of the two heads of the gastrocnemius muscle.
Continuing ascending the posterior aspect of the lower leg along the gastrocnemius and soleus muscle, it binds again on both sides of the popliteal crease.
The Sinew Channel ascends further along the posterior aspect of the thigh and binds at the center of the gluteal crease.
It then ascends further as a broad band along the spine. Two branches separate from the main Channel in the back at the level of the axilla:
The other branch crosses beneath the axilla, then ascends the chest to supraclavicular fossa. Two subbranches separates from here:
One goes up further and bind at Wangu GB-12 behind the ear.
The other crosses to Quanliao SI-18 on the lower border of zygoma.
The main Channel continues ascending and binds at Tianzhu BL-10 in the occipital area.
A small branch penetrates deep to the root of the tongue and binds there.
The main Channel ascends further, crosses the head to the midline and reaches the inner eye canthus. Two more branches separate from here:
One descends the cheek and binds lateral to the nose.
The other circles the eyes and form a network around the eyes with the Stomach Sinew Channel. It then penetrates deep to connect with the other branch at the root of the tongue.
The Bladder Luo-Connecting Vessel System separates from the Primary Channel at Feiyang BL-58, at the posterior border of the fibula and at the lower border of the gastrocnemius muscle.