3 cun (about 4 finger-breadths) lateral to the lower border of the spinous process of the 2nd thoracic vertebra (T2)
How to locate
First locate the spinous process of the 7th cervical vertebra (C7), which is still palpable when the neck is being flexed and extended, while the 6th cervical vertebra (C6) starts to slide anteriorly and gradually disappears.
The spinous process of the 2nd thoracic vertebra (T2) is two spinous process below C7.
Fufen BL-41 is 3 cun lateral to the lower border of T2. Fengmen BL-12 is at the same level but 1.5 cun lateral to T2.
Points located between BL-41 and BL-54 are the outer branch of the Bladder Channel, while these between BL-12 and BL-30 are the inner branch.