The hidden helper of the Triple Burner. Weiyang (BL-39) sits quietly at the back of the knee, yet reaches deep into the body's water pathways — regulating the lower Jiao, supporting the Bladder, and acting as the Lower He-Sea point of the Triple Burner (San Jiao) channel.
Contraindications
Weiyang (BL-39) is generally a safe point. As with all points in the popliteal region, take care to avoid the nearby vessels — insert carefully and do not needle blindly or forcefully in this area.
Name & story
The name 委阳 Weiyang means "Yang in the Bend" or "委" — to bend, to tuck away — and 阳 Yang, referring to the outer (Yang) side of the popliteal crease. The point is tucked to the outer edge of the hollow behind the knee, as if quietly stepping aside from its more famous neighbour Weizhong BL-40 at the centre. Yet its position on the Yang side is not accidental — the Triple Burner is a Yang organ, and this is where its lower root touches the earth.
Point family & character
Weiyang (BL-39) belongs to the Bladder Meridian (BL), but its most important character is that it is the Lower He-Sea point of the Triple Burner (San Jiao) channel. The He-Sea points are where the channel energy pours into the body's deeper layers, and the lower He-Sea points of the Yang organs of the abdomen are especially powerful for treating disorders of those organs. BL-39 is the gateway through which the Triple Burner's Qi reaches the lower Jiao.
Five-element dynamics
The Triple Burner (San Jiao) is the great organiser of water and Qi transformation throughout the three Jiao — upper, middle and lower. Its Lower He-Sea point, BL-39, is the place where the Triple Burner's influence becomes most concrete and physical, governing the movement and transformation of water in the lower body. When water is stuck — when Dampness accumulates, or the Bladder cannot transform fluids freely — this point helps open the lower Jiao's gate and restore the smooth flow of Qi and water.
Location
Find the hollow at the back of the knee (the popliteal crease). Weiyang (BL-39) sits at the outer (lateral) end of this crease, just to the inside of the thick tendon of the biceps femoris muscle — the tendon you can feel on the outer side of the knee when you bend it. It is lateral to Weizhong BL-40, which sits at the centre of the same crease.
Anatomy & fascia
The point lies at the lateral end of the popliteal crease, on the medial border of the biceps femoris tendon, in the region of the common peroneal nerve and the lateral popliteal vessels.
Needling
The needle is inserted perpendicularly. The needling sensation may radiate down the leg.
The golden tip
If you experience tension or achiness behind the knee, or feel puffy and waterlogged in the legs, you can find Weiyang (BL-39) at the outer corner of the crease behind the knee, just inside the prominent tendon there. Press or massage the point gently for one to two minutes on each side. It is easiest to reach with the knee slightly bent.
For education only — not medical advice. Consult a qualified practitioner.