3 cun (about 4 finger-breadths) lateral to the lower border of the spinous process of the 6th thoracic vertebra (T6).
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 6th thoracic vertebra (T6) is six spinous process below C7.
Or locate the spinous process of T7, which is level with the inferior angle of the scapula, when the patient is seated with their arms hanging down. T6 is one thoracic vertebra above.
Yixi BL-45 is 3 cun lateral to the lower border of T6. Dushu BL-16 is at the same level but 1.5 cun lateral to T6.
Points located between BL-41 and BL-54 are in the outer branch of the Bladder Channel, while these between BL-12 and BL-30 are in the inner branch.