The meridian begins at the inner corner of the eye, rises over the forehead, reaches the vertex where a branch penetrates towards the brain, then descends the nape. It divides into two branches parallel to the spine, one at one and a half finger-widths from the midline, the other at three. Both descend the back and lumbar region, meet at the popliteal crease, travel down the calf, pass behind the lateral malleolus, follow the outer border of the foot and end at the outer nail corner of the fifth toe.
The Bladder stores and discharges used fluids, under the action of Kidney Qi to which it is paired. Its therapeutic role goes far beyond that function: the Back-Shu points it carries give access to each organ and bowel, making it a meridian of general regulation. Its upper branch treats headaches, eye disorders and neck stiffness; its back branch treats low-back pain and sciatica; its distal points serve to clear heat and release the exterior.